This study was supported by the Department of Veterans Affairs (VA-ORD BLR&#38;D Merit I01BX004536), and the National Institute of Health grants # 1R01DK105183, DK120394, and DK118529 to HW. We thank Dr. Hongju Wu for sharing technical experience.

All procedures were conducted with the approval of the Institutional Animal Care and Use Committees at the Medical University of South Carolina and the Ralph H. Johnson Medical Center. C57BL/6J male mice between 8-10 weeks of age were used in this study. Mice were housed under a standard 12 light/ 12 dark cycle with ad libitumaccess to food and water.
1. Preparation of TNBS solution for injection
<ol>
	<li>Prepare 10% ethanol in 0.9% saline. Dissolve stock TNBS (see Table of Materials) in 10% ethanol to a final concentration of 7.5 mM by adding 7.5 &#181;L of TNBS into 1 mL of 10% ethanol. 
	CAUTION: TNBS presents a chemical hazard. Prepare the solution inside a fume hood and use personal protective equipment such as gloves, goggles, and a lab coat to avoid direct contact with TNBS.</li>
	<li>Load 50 &#181;L of 0.75% TNBS solution into an insulin syringe with a 31-gauge needle. Load 50 &#181;L of 10% ethanol in saline into a syringe of the same size as vehicle control. Place the syringes on ice and protect them from light until needed.</li>
</ol>
2. Mouse preparation and surgery
<ol>
	<li>Shave the hair from the abdominal surgical area.</li>
	<li>Inject one pre-emptive dose of the analgesic (e.g., buprenorphine 0.1 mg/kg i.p.) before surgery.</li>
	<li>Induce and maintain the mouse under general anesthesia with 1.5-2% isoflurane and 1 L/min of oxygen. Confirm the anesthetization by pinching the toes and observing the animal for a lack of reflex.</li>
	<li>Place the mouse on a heated surgical pad during surgery. Apply veterinary ointment on each eye when the mouse is under anesthesia.</li>
	<li>Disinfect the surgical site by wiping the surgical area 3x with 2% iodine, followed by 70% alcohol (Table of Materials).</li>
	<li>Perform a laparotomy with micro scissors to generate a 0.5-1 cm incision.</li>
	<li>Gently expose the duodenum and locate the common bile duct using cotton swabs (Table of Materials).</li>
	<li>Place a straight micro hemo clip (Table of Materials) over the proximal common duct to prevent the flow of TNBS or vehicle solutions into the liver and the gallbladder (Figure 1A, B).</li>
	<li>Gently expose the duodenum and insert the needle into the pancreatic duct through the papilla of Vater.</li>
	<li>Once the needle is inside the duct, place a curved micro hemo clip (Table of Materials) over the duodenum surrounding the needle (Figure 1A) to secure the needle in place and prevent the injected solution from entering the duodenum.</li>
	<li>Gradually infuse the solution (TNBS or vehicle) into the pancreatic duct over the course of one min. 
	NOTE: TNBS needs to be infused slowly over one min of time, and it is easy to control the infusion speed when the pancreas is perfused with an insulin syringe with a 5/16 inch and 31G needle. Keep the hand as stable as possible to avoid pricking the bile duct. If TNBS is successfully injected, yellow color may be visible inside the pancreas.</li>
	<li>After infusion, carefully remove the micro clamp near the liver, and then remove the micro clamp holding the needle and the duodenum.</li>
	<li>Carefully return the duodenum to its original position.</li>
	<li>Leave 0.5 mL of warm sterile saline (36-37 &#176;C) in the abdominal cavity before closure, to help the duodenum return to its original position and assist with the recovery of peristalsis.</li>
	<li>Close the incision in the muscle layer using continuous suture with a 5-0 stitch. Close the skin using interrupted suture with a 4-0 stitch.</li>
	<li>Place the cage containing mice on a heating pad to allow recovery from the anesthesia.</li>
	<li>Confirm that the mice are warm and capable of spontaneous movement before returning them to the holding room.</li>
	<li>Continue to provide an analgesic (e.g., buprenorphine 0.1 mg/kg i.p.) every 12 h and supplemental heat for 48 h post-surgery.</li>
</ol>
3. Monitoring mouse behavior
<ol>
	<li>Remove sutures at day 7 post-surgery.</li>
	<li>Monitor mouse health and behavior daily during the first-week post-surgery. Watch for signs of distress such as vocalizing, hunched back posture, or reduced locomotion. Measure the body weight every other day.</li>
	<li>Use Von Frey monofilaments (VFFs) to measure abdominal mechanical hypersensitivity before, and 2, 3 weeks post-surgery as described9,14.
	<ol>
		<li>Apply VFFs of different applied forces in the ascending order to the upper abdominal area 10x every 1-2 s. Consider the raising, retraction, or licking of the abdomen (withdrawal response) as a positive response.</li>
		<li>Apply a stronger stimulus if a positive response is not observed, and a weaker stimulus if a positive response is observed. The withdrawal threshold is the force at which the mouse responds 50% of the time.</li>
	</ol>
	</li>
</ol>
4. Collection and histological analysis of pancreatic tissue
<ol>
	<li>Sacrifice the mice under anesthesia by cervical dislocation, and carefully dissect the pancreas from the intestine and other organs.</li>
	<li>Fix the pancreas in 10% paraformaldehyde for 24 h, embed in paraffin, cut tissue sections of 5 &#181;m thickness, and place them on glass slides for staining.</li>
	<li>Perform hematoxylin-eosin, and Masson&#39;s trichrome staining using standard methods as previously reported4.</li>
</ol>

<ol>
	<li>Klauss, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetically+induced+vs.+classical+animal+models+of+chronic+pancreatitis:+a+critical+comparison.">Genetically induced vs. classical animal models of chronic pancreatitis: a critical comparison.</a> The Federation of American Societies for Experimental Biology Journal. 32, 5778-5792 (2018).</li><li>Liao, Y. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Histone+deacetylase+2+is+involved+in+&#181;-opioid+receptor+suppression+in+the+spinal+dorsal+horn+in+a+rat+model+of+chronic+pancreatitis+pain.">Histone deacetylase 2 is involved in &#181;-opioid receptor suppression in the spinal dorsal horn in a rat model of chronic pancreatitis pain.</a> Molecular Medicine Reports. 17 (2), 2803-2810 (2018).</li><li>Gui, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Trypsin+activity+governs+increased+susceptibility+to+pancreatitis+in+mice+expressing+human+PRSS1R122H.">Trypsin activity governs increased susceptibility to pancreatitis in mice expressing human PRSS1R122H.</a> The Journal of Clinical Investigation. 130 (1), 189-202 (2020).</li><li>Sun, Z., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adipose+Stem+Cell+Therapy+Mitigates+Chronic+Pancreatitis+via+Differentiation+into+Acinar-like+Cells+in+Mice.">Adipose Stem Cell Therapy Mitigates Chronic Pancreatitis via Differentiation into Acinar-like Cells in Mice.</a> Molecular Therapy. 25 (11), 2490-2501 (2017).</li><li>Aghdassi, A. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+for+investigating+chronic+pancreatitis.">Animal models for investigating chronic pancreatitis.</a> Fibrogenesis and Tissue Repair. 4 (1), 26 (2011).</li><li>Scoggins, C. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=p53-dependent+acinar+cell+apoptosis+triggers+epithelial+proliferation+in+duct-ligated+murine+pancreas.">p53-dependent acinar cell apoptosis triggers epithelial proliferation in duct-ligated murine pancreas.</a> American Journal of Physiology-Gastrointestinal and Liver Physiology. 279 (4), 827-836 (2000).</li><li>Bradley, E. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pancreatic+duct+pressure+in+chronic+pancreatitis.">Pancreatic duct pressure in chronic pancreatitis.</a> The American Journal of Surgery. 144 (3), 313-316 (1982).</li><li>Zhao, J. B., Liao, D. H., Nissen, T. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+of+pancreatitis:+can+it+be+translated+to+human+pain+study.">Animal models of pancreatitis: can it be translated to human pain study.</a> World Journal of Gastroenterology. 19 (42), 7222-7230 (2013).</li><li>Winston, J. H., He, Z. J., Shenoy, M., Xiao, S. Y., Pasricha, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+and+behavioral+changes+in+nociception+in+a+novel+rat+model+of+chronic+pancreatitis+for+the+study+of+pain.">Molecular and behavioral changes in nociception in a novel rat model of chronic pancreatitis for the study of pain.</a> Pain. 117 (1-2), 214-222 (2005).</li><li>Cattaruzza, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transient+receptor+potential+ankyrin+1+mediates+chronic+pancreatitis+pain+in+mice.">Transient receptor potential ankyrin 1 mediates chronic pancreatitis pain in mice.</a> American Journal of Physiology-Gastrointestinal and Liver Physiology. 304 (11), 1002-1012 (2013).</li><li>Bai, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anterior+insular+cortex+mediates+hyperalgesia+induced+by+chronic+pancreatitis+in+rats.">Anterior insular cortex mediates hyperalgesia induced by chronic pancreatitis in rats.</a> Molecular Brain. 12 (1), 76 (2019).</li><li>Puig-Div&#237;, V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Induction+of+chronic+pancreatic+disease+by+trinitrobenzene+sulfonic+acid+infusion+into+rat+pancreatic+ducts.">Induction of chronic pancreatic disease by trinitrobenzene sulfonic acid infusion into rat pancreatic ducts.</a> Pancreas. 13 (4), 417-424 (1996).</li><li>Zhang, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=PAX4+Gene+Transfer+Induces+alpha-to-beta+Cell+Phenotypic+Conversion+and+Confers+Therapeutic+Benefits+for+Diabetes+Treatment.">PAX4 Gene Transfer Induces alpha-to-beta Cell Phenotypic Conversion and Confers Therapeutic Benefits for Diabetes Treatment.</a> Molecular Therapy. 24 (2), 251-260 (2016).</li><li>Ceppa, E. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Serine+proteases+mediate+inflammatory+pain+in+acute+pancreatitis.">Serine proteases mediate inflammatory pain in acute pancreatitis.</a> American Journal of Physiology-Gastrointestinal and Liver Physiology. 300 (6), 1033-1042 (2011).</li><li>Puig-Divi, V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Induction+of+chronic+pancreatic+disease+by+trinitrobenzene+sulfonic+acid+infusion+into+rat+pancreatic+ducts.">Induction of chronic pancreatic disease by trinitrobenzene sulfonic acid infusion into rat pancreatic ducts.</a> Pancreas. 13 (4), 417-424 (1996).</li><li>Xu, G. Y., Winston, J. H., Shenoy, M., Yin, H., Pasricha, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhanced+excitability+and+suppression+of+A-type+K++current+of+pancreas-specific+afferent+neurons+in+a+rat+model+of+chronic+pancreatitis.">Enhanced excitability and suppression of A-type K+ current of pancreas-specific afferent neurons in a rat model of chronic pancreatitis.</a> American Journal of Physiology-Gastrointestinal and Liver Physiology. 291 (3), 424-431 (2006).</li><li>Drewes, A. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pain+in+chronic+pancreatitis:+the+role+of+neuropathic+pain+mechanisms.">Pain in chronic pancreatitis: the role of neuropathic pain mechanisms.</a> Gut. 57 (11), 1616-1627 (2008).</li></ol>

All authors declare that they do not have conflict of interest.

Bile duct infusion of TNBS to induce chronic pancreatitis is technically challenging in mice, as up to 22.5% of mice can die within 3-4 days of drug infusion10. Here, this report refined the procedure based on previous studies and reduced early mouse mortality to &#60;10%. For example, the increased drug volume (from 35 &#956;L to 50&#956;L) can ensure the drugs reach&#160;the whole pancreas. Using an insulin syringe and a smaller needle size (31G) reduces potential damage to the pancreatic duct and the leakage of bile into the gallbladder or the abdomen, which most likely would cause mouse death within the first several days after surgery. Clamping both ends of the bile duct can prevent TNBS from leaking to the gallbladder and the intestine, which may cause mortality. The hemo clips restrain TNBS within the injected pancreas, improving the efficacy while reducing damages to other tissues. In addition, TNBS is not stable at temperatures above 0 &#176;C. Therefore, by using freshly prepared TNBS, CP induction achieved stable results.
This protocol effectively induces CP in male C57BL/6J mice at 8-12 weeks of age&#160;and generates a model that mimics major symptoms of chronic pancreatitis, including bodyweight loss, pancreatic atrophy, fibrosis, and likely abdominal pain. Compared to other CP mouse models, the TNBS model is widely used to evaluate analgesic effects in addition to inflammation10,15,16. The other advantage of the TNBS model is that the drug is injected directly into the pancreas, which reduces damage to other organs that may interfere with the study17. This TNBS CP mouse model can be used to study pathogenesis as well as treatment options together with other chronic pancreatitis models.
One limitation of this study is that only mice between 8-10 weeks of age were used. Since mice at different ages may have difference pancreas sizes, which consequently affect TNBS-CP development. Therefore, whether mice at different ages/sizes should be given a different dose of TNBS needs to be tested. Nevertheless, this study demonstrates the procedures to successfully perform pancreatic duct infusion that may help with studies focused on pancreatic diseases.

Chronic pancreatitis (CP) is a chronic inflammatory disease characterized by the atrophy of the pancreas, fibrosis, abdominal pain, and eventual loss of both exocrine and endocrine functions1. Current medical and surgical treatments are not curative but are undertaken to relieve symptoms that are the consequence of the disease: refractory abdominal pain, endocrine and exocrine dysfunction. Therefore, more effective treatments are urgently needed2. Animal models provide an essential tool for developing a better understanding of the disease and investigating potential therapeutics3. Multiple mouse models for CP have been developed, of which cerulein and/or alcohol models are commonly used. Cerulein, an oligopeptide stimulating pancreatic secretion, has been shown to reproducibly induce a CP model featuring pancreatic atrophy, fibrosis, among others4. Another common model uses serial injections of L-arginine, which produces exocrine insufficiency similar to that observed in human patients5. CP can also be induced by complete or partial pancreatic duct ligation, as well as pancreatic duct hypertension6,7. Despite the variety of animal models available for CP, none of these models effectively reproduces the abdominal pain experienced by CP patients8.
Previous studies showed that local pancreatic injection of 2,4,6 -trinitrobenzene sulfonic acid (TNBS) replicates the persistent pain experienced by CP patients9,10,11. TNBS-treated mice demonstrated abdominal hypersensitivity and increased pain-related behaviors as well as a &#34;generalized hypersensitivity&#34; to painful stimuli, a phenomenon that has been observed in CP patients10. In addition to accurately mimicking CP pain, the TNBS model also replicates other pathological features of the human condition such as fibrosis, mononuclear cell infiltration, and replacement of acinar cells with fatty tissue10,12. However, TNBS infusion via bile duct is a technically challenging procedure in mice that may cause death. To our knowledge, there is no visual protocol to show how bile duct infusion is performed. In this article, we demonstrate the procedure of the bile duction infusion of TNBS to generate a CP mouse model. This procedure will help generate valuable animal models for the study of CP and other pancreatic diseases and can be used to infuse other materials (e.g., virus, cells) into the pancreas13.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>10% Neutral buffered formalin v/v</td>
			<td>Fisher Scientific</td>
			<td>23426796</td>
			<td></td>
		</tr>
		<tr>
			<td>Alcohol prep pads, sterile</td>
			<td>Fisher Scientific</td>
			<td>22-363-750</td>
			<td></td>
		</tr>
		<tr>
			<td>Animal Anesthesia system</td>
			<td>VetEquip, Inc.</td>
			<td>901806</td>
			<td></td>
		</tr>
		<tr>
			<td>Buprenorphine hydrochloride, injection</td>
			<td>Par Sterile Products, LLC</td>
			<td>NDC 42023-179-05</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge tubes, 15 mL</td>
			<td>Fisher Scientific</td>
			<td>0553859A</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol, absolute (200 proof), molecular biology grade</td>
			<td>Fisher Scientific</td>
			<td>BP2818500</td>
			<td></td>
		</tr>
		<tr>
			<td>Extra fine Micro Dissecting scissors 4&#8221; straight sharp</td>
			<td>Roboz Surgical Instrument Co.</td>
			<td>RS-5882</td>
			<td></td>
		</tr>
		<tr>
			<td>Graefe forceps 4&#8221; extra delicate tip</td>
			<td>Roboz Surgical Instrument Co.</td>
			<td>RS-5136</td>
			<td></td>
		</tr>
		<tr>
			<td>Heated pad</td>
			<td>Amazon</td>
			<td>B07HMKMBKM</td>
			<td></td>
		</tr>
		<tr>
			<td>Hegar-Baumgartner Needle Holder 5.25&#8221;</td>
			<td>Roboz Surgical Instrument Co.</td>
			<td>RS-7850</td>
			<td></td>
		</tr>
		<tr>
			<td>Insulin syringe with 31-gauge needle</td>
			<td>BD</td>
			<td>324909</td>
			<td></td>
		</tr>
		<tr>
			<td>Iodine prep pads</td>
			<td>Fisher Scientific</td>
			<td>19-027048</td>
			<td></td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>Piramal Critical Care</td>
			<td>NDC 66794-017-25</td>
			<td></td>
		</tr>
		<tr>
			<td>Micro clip applying forceps 5.5&#8221;</td>
			<td>Roboz Surgical Instrument Co.</td>
			<td>RS-5410</td>
			<td></td>
		</tr>
		<tr>
			<td>Micro clip, straight strong curved 1x6mm</td>
			<td>Roboz Surgical Instrument Co.</td>
			<td>RS-5433</td>
			<td></td>
		</tr>
		<tr>
			<td>Micro clip, straight, 0.75mm clip width</td>
			<td>Roboz Surgical Instrument Co.</td>
			<td>RS-5420</td>
			<td></td>
		</tr>
		<tr>
			<td>Picrylsulfonic acid solution, TNBS, 1M in H2O</td>
			<td>Millipore Sigma</td>
			<td>92822-1ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Polypropylene Suture 4-0</td>
			<td>Med-Vet International</td>
			<td>MV-8683</td>
			<td></td>
		</tr>
		<tr>
			<td>Polypropylene Suture 5-0</td>
			<td>Med-Vet International</td>
			<td>MV-8661</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium chloride, 0.9% intravenous solution</td>
			<td>VWR</td>
			<td>2B1322Q</td>
			<td></td>
		</tr>
		<tr>
			<td>Surgical drape, sterile</td>
			<td>Med-Vet International</td>
			<td>DR1826</td>
			<td></td>
		</tr>
		<tr>
			<td>Tissue Cassette</td>
			<td>Fisher Scientific</td>
			<td>22-272416</td>
			<td></td>
		</tr>
		<tr>
			<td>Von Frey filaments</td>
			<td>Bioseb</td>
			<td>EB2-VFF</td>
			<td></td>
		</tr>
	</tbody>
</table>

a mouse model for chronic pancreatitis via bile duct tnbs infusion

Chronic pancreatitis (CP) is a complex disease involving pancreatic inflammation and fibrosis, glandular atrophy, abdominal pain and other symptoms. Several rodent models have been developed to study CP, of which the bile duct 2,4,6 -trinitrobenzene sulfonic acid (TNBS) infusion model replicates the features of neuropathic pain seen in CP. However, bile duct drug infusion in mice is technically challenging. This protocol demonstrates the procedure of bile duct TNBS infusion for generation of a CP mouse model. TNBS was infused into the pancreas through the ampulla of Vater in the duodenum. This protocol optimized drug volume, surgical techniques, and drug handling during the procedure. TNBS-treated mice showed features of CP as reflected by bodyweight and pancreas weight reductions, changes in pain-associated behaviors, and abnormal pancreatic morphology. With these improvements, mortality associated with TNBS injection was minimal. This procedure is not only critical in generating pancreatic disease models but is also useful in local pancreatic drug delivery.

The bile duct infusion procedures were optimized to reduce mouse mortality associated with this procedure10. TNBS was first given in a total volume of 35 &#956;L or 50 &#956;L. Injection of TNBS in a volume of 50 &#956;L could reach the whole pancreas and induce a more homogeneous disease phenotype (Figure 1B). In addition, injection of TNBS using insulin syringe with 31G needle could better control infusion speed relative to regular syringes and needle sizes. Freshly prepared TNBS stored on ice and used within one hour of drug preparation also yielded better outcome compared to TNBS prepared longer than one hour. With these improvements, the mortality of recipients was controlled and remained under 10%.
Body weight loss is one of the characteristics of CP. Mice in the control group lost around 6% of their original body weight during the first 3 days after surgery, then gradually recovered (104.6% of original body weight at day 21) (Figure 1C). In contrast, mice receiving TNBS lost on average about 15% of their original body weight during the first 5 days and regained weight afterward (99.8% of original body weight at day 21) (Figure 1C). In addition, compared to controls, TNBS mice showed increased abdominal mechanical hypersensitivity at 2 and 3 weeks after TNBS injection (Figure 1D), which was likely associated with increased abdominal pain10.
To confirm that the bile duct TNBS infusion effectively induced pancreatic changes mimicking human CP, we collected pancreatic tissues from TNBS or vehicle-treated control mice at 3 weeks post-surgery. Both size, and weight per body weight of the pancreas were significantly reduced in TNBS mice compared with controls (Figure 2A,B), suggesting marked pancreatic atrophy consistent with the findings in humans with severe and long-term CP. In addition, the pancreas from the control mice appeared normal without obvious morphological changes, while TNBS mice showed vacuolization with massive loss of acinar cells replaced by fat cell infiltration and fibrosis (Figure 2C). These findings were consistent with reports from other studies9,10.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/62080/62080fig01.jpg" /> 
Figure 1:&#160;TNBS bile duct infusion for CP mice generation. (A) Illustration of bile duct injection. (B) Bile duct after injection of 50 &#956;L of ink. (C) Averages of body weight change in mice receiving TNBS or vehicle. (D) Abdominal response threshold in TNBS and control mice at 3 weeks after infusion. Data were analyzed using available analysis software (e.g., GraphPad 8.2.1). Data are presented as mean &#177; SEM. Differences between groups were analyzed using the Student&#39;s t-test, ** p &#60; 0.01 was considered statistically significant. <a href="https://www.jove.com/files/ftp_upload/62080/62080fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/62080/62080fig02.jpg" /> 
Figure 2.&#160;Characterization of CP in TNBS-treated mice. (A) Micrographs of the pancreas from control (CTR) and TNBS mice. (B) The average pancreas weight divided by mouse bodyweight in CTR and TNBS mice. (C) Hematoxylin and eosin staining of pancreas sections of CTR and TNBS mice. Scale bar =100 &#956;m. Data are presented as mean &#177; SEM. **, p &#60; 0.01 by Student&#39;s t-test. <a href="https://www.jove.com/files/ftp_upload/62080/62080fig02large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about A Mouse Model for Chronic Pancreatitis via Bile Duct TNBS Infusion at JoVE.com

A Mouse Model for Chronic Pancreatitis via Bile Duct TNBS Infusion

Chronic pancreatitis (CP) is a disease characterized by inflammation and fibrosis of the pancreas, often associated with intractable abdominal pain. This article focuses on refining the technique to generate a mouse model of CP via bile duct infusion with 2,4,6 -trinitrobenzene sulfonic acid (TNBS).

Chronic pancreatitis (CP) is a complex disease involving pancreatic inflammation and fibrosis, glandular atrophy, abdominal pain and other symptoms. ...

a-mouse-model-for-chronic-pancreatitis-via-bile-duct-tnbs-infusion

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3.8K Views.  Medical University of South Carolina. Chronic pancreatitis (CP) is a disease characterized by inflammation and fibrosis of the pancreas, often associated with intractable abdominal pain. This article focuses on refining the technique to generate a mouse model of CP via bile duct infusion with 2,4,6 -trinitrobenzene sulfonic acid (TNBS). 

Video: A Mouse Model for Chronic Pancreatitis via Bile Duct TNBS Infusion

Cannulation of the Mouse Submandibular Salivary Gland via the Wharton's Duct

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(impaired chewing and swallowing), severe dental caries, altered taste, oro-pharyngeal infections (candidiasis), mucositis, pain and discomfort.
One innovative approach of regenerative medicine for the treatment of salivary gland hypo-function is speculated in RS Redman, E Mezey 
et al. 2009: stem cells can be directly deposited by cannulation into the gland as a potent method in reviving the functions of the impaired organ. Presumably, 
the migrated foreign stem cells will differentiate into glandular cells to function as part of the host salivary gland. Also, this cannulation technique is an 
expedient and effective delivery method for clinical gene transfer application.
Here we illustrate the steps involved in performing the cannulation procedure on the mouse submandibular salivary gland via the Wharton's duct 
(Fig 1). C3H mice (Charles River, Montreal, QC, Canada) are used for this experiment, which have been kept under clean conventional conditions at 
the McGill University animal resource center. All experiments have been approved by the University Animal Care Committee and were in accordance with the 
guidelines of the Canadian Council on Animal Care.
For this experiment, a trypan blue solution is infused into the gland through the opening of the Wharton's duct using a 
insulin syringe with a 29-gauge needle encased inside a polyethylene tube. Subsequently, the mouse is dissected to show that the infusions migrated 
into the gland successfully.

A protocol for the cannulation of the mouse submandibular salivary gland via the Wharton's duct is described. For this experiment, the trypan blue solution is used as a dyer to demonstrate how this technique effectively delivers infusions into the targeted gland, and to suggest the reliability of this new approach as a potential clinical drug/cell therapy for the regeneration of salivary glands.

Severe salivary gland hypofunction is frequently found in patients with Sj&ouml;gren's syndrome and those who receiving therapeutic 
irradiation in their ...

3-Dimensional Resin Casting and Imaging of Mouse Portal Vein or Intrahepatic Bile Duct System

In organs, the correct architecture of vascular and ductal structures is indispensable for proper physiological function, and the formation and maintenance of these structures is a highly regulated process. The analysis of these complex, 3-dimensional structures has greatly depended on either 2-dimensional examination in section or on dye injection studies. These techniques, however, are not able to provide a complete and quantifiable representation of the ductal or vascular structures they are intended to elucidate. Alternatively, the nature of 3-dimensional plastic resin casts generates a permanent snapshot of the system and is a novel and widely useful technique for visualizing and quantifying 3-dimensional structures and networks.
A crucial advantage of the resin casting system is the ability to determine the intact and connected, or communicating, structure of a blood vessel or duct. The structure of vascular and ductal networks are crucial for organ function, and this technique has the potential to aid study of vascular and ductal networks in several ways. Resin casting may be used to analyze normal morphology and functional architecture of a luminal structure, identify developmental morphogenetic changes, and uncover morphological differences in tissue architecture between normal and disease states. Previous work has utilized resin casting to study, for example, architectural and functional defects within the mouse intrahepatic bile duct system that were not reflected in 2-dimensional analysis of the structure1,2, alterations in brain vasculature of a Alzheimer's disease mouse model3, portal vein abnormalities in portal hypertensive and cirrhotic mice4, developmental steps in rat lymphatic maturation between immature and adult lungs5, immediate microvascular changes in the rat liver, pancreas, and kidney in response in to chemical injury6.
Here we present a method of generating a 3-dimensional resin cast of a mouse vascular or ductal network, focusing specifically on the portal vein and intrahepatic bile duct. These casts can be visualized by clearing or macerating the tissue and can then be analyzed. This technique can be applied to virtually any vascular or ductal system and would be directly applicable to any study inquiring into the development, function, maintenance, or injury of a 3-dimensional ductal or vascular structure.

A method of visualizing and quantifying the 3-dimensional structure of mouse hepatic portal vein or intrahepatic bile duct is described. This resin cast technique can also be applied to other ductal or vascular systems and allows for in situ visualization or quantification of a system's intact communicating architecture.

In  organs, the correct architecture of vascular and ductal structures is  indispensable for proper physiological function, and the formation and  ...

A Model of Chronic Nutrient Infusion in the Rat

Chronic exposure to excessive levels of nutrients is postulated to affect the function of several organs and tissues and to contribute to the development of the many complications associated with obesity and the metabolic syndrome, including type 2 diabetes. To study the mechanisms by which excessive levels of glucose and fatty acids affect the pancreatic beta-cell and the secretion of insulin, we have established a chronic nutrient infusion model in the rat. The procedure consists of catheterizing the right jugular vein and left carotid artery under general anesthesia; allowing a 7-day recuperation period; connecting the catheters to the pumps using a swivel and counterweight system that enables the animal to move freely in the cage; and infusing glucose and/or Intralipid (a soybean oil emulsion which generates a mixture of approximately 80% unsaturated/20% saturated fatty acids when infused with heparin) for 72 hr. This model offers several advantages, including the possibility to finely modulate the target levels of circulating glucose and fatty acids; the option to co-infuse pharmacological compounds; and the relatively short time frame as opposed to dietary models. It can be used to examine the mechanisms of nutrient-induced dysfunction in a variety of organs and to test the effectiveness of drugs in this context.

A protocol for chronic infusions of glucose and Intralipid in rats is described. This model can be used to study the impact of nutrient excess on organ function and physiological parameters.

Chronic exposure to excessive levels of nutrients is postulated to  affect the function of several organs and tissues and to contribute to the  ...

A Laser-induced Mouse Model of Chronic Ocular Hypertension to Characterize Visual Defects

Glaucoma, frequently associated with elevated intraocular pressure (IOP), is one of the leading causes of blindness. We sought to establish a mouse model of ocular hypertension to mimic human high-tension glaucoma. Here laser illumination is applied to the corneal limbus to photocoagulate the aqueous outflow, inducing angle closure. The changes of IOP are monitored using a rebound tonometer before and after the laser treatment. An optomotor behavioral test is used to measure corresponding changes in visual capacity. The representative result from one mouse which developed sustained IOP elevation after laser illumination is shown. A decreased visual acuity and contrast sensitivity is observed in this ocular hypertensive mouse. Together, our study introduces a valuable model system to investigate neuronal degeneration and the underlying molecular mechanisms in glaucomatous mice.

Chronic ocular hypertension is induced using laser photocoagulation of the trabecular meshwork in mouse eyes. The intraocular pressure (IOP) is elevated for several months after laser treatment. The decrease of visual acuity and contrast sensitivity of experimental animals are monitored using the optomotor test.

Glaucoma, frequently associated with elevated intraocular pressure (IOP), is one of the leading causes of blindness. We sought to establish a mouse model ...

Urinary Bladder Distention Evoked Visceromotor Responses as a Model for Bladder Pain in Mice

Approximately 3-8 million people in the United States suffer from interstitial cystitis/bladder pain syndrome (IC/BPS), a debilitating condition characterized by increased urgency and frequency of urination, as well as nocturia and general pelvic pain, especially upon bladder filling or voiding. Despite years of research, the cause of IC/BPS remains elusive and treatment strategies are unable to provide complete relief to patients. In order to study nervous system contributions to the condition, many animal models have been developed to mimic the pain and symptoms associated with IC/BPS. One such murine model is urinary bladder distension (UBD). In this model, compressed air of a specific pressure is delivered to the bladder of a lightly anesthetized animal over a set period of time. Throughout the procedure, wires in the superior oblique abdominal muscles record electrical activity from the muscle. This activity is known as the visceromotor response (VMR) and is a reliable and reproducible measure of nociception. Here, we describe the steps necessary to perform this technique in mice including surgical manipulations, physiological recording, and data analysis. With the use of this model, the coordination between primary sensory neurons, spinal cord secondary afferents, and higher central nervous system areas involved in bladder pain can be unraveled. This basic science knowledge can then be clinically translated to treat patients suffering from IC/BPS.

Approximately 3-8 million people in the United States suffer from interstitial cystitis/bladder pain syndrome (IC/BPS), a debilitating condition characterized in part by pelvic pain. In order to study nervous system contributions to the condition, a physiological model of urinary bladder pain is used in mice and rats.

Approximately 3-8 million people in the United States suffer from interstitial cystitis/bladder pain syndrome (IC/BPS), a debilitating condition ...

Bile Duct Ligation in Mice: Induction of Inflammatory Liver Injury and Fibrosis by Obstructive Cholestasis

In most vertebrates, the liver produces bile that is necessary to emulsify absorbed fats and enable the digestion of lipids in the small intestine as well as to excrete bilirubin and other metabolic products. In the liver, the experimental obstruction of the extrahepatic biliary system initiates a complex cascade of pathological events that leads to cholestasis and inflammation resulting in a strong fibrotic reaction originating from the periportal fields. Therefore, surgical ligation of the common bile duct has become the most commonly used model to induce obstructive cholestatic injury in rodents and to study the molecular and cellular events that underlie these pathophysiological mechanisms induced by inappropriate bile flow. In recent years, different surgical techniques have been described that either allow reconnection or reanastomosis after bile duct ligation (BDL), e.g., partial BDL, or other microsurgical methods for specific research questions. However, the most frequently used model is the complete obstruction of the common bile duct that induces a strong fibrotic response after 21 to 28 days. The mortality rate can be high due to infectious complications or technical inaccuracies. Here we provide a detailed surgical procedure for the BDL model in mice that induce a highly reproducible fibrotic response in accordance to the 3R rule for animal welfare postulated by Russel and Burch in 1959.

Disruption of bile flow results in severe inflammatory cholestatic liver injury with a characteristic time-dependent sequence of morphological alterations. Here we present a protocol for the surgical ligation of the common bile duct in mice that allows to induce a strong fibrotic response after 21 to 28 days.

In most vertebrates, the liver produces bile that is necessary to emulsify absorbed fats and enable the digestion of lipids in the small intestine as well ...

Neurodegeneration in an Animal Model of Chronic Amyloid-beta Oligomer Infusion Is Counteracted by Antibody Treatment Infused with Osmotic Pumps

Decline in hippocampal-dependent explicit memory (memory for facts and events) is one of the earliest clinical symptom of Alzheimer&#39;s disease (AD). It is well established that synapse loss and ensuing neurodegeneration are the best predictors for memory impairments in AD. Latest studies have emphasized the neurotoxic role of soluble amyloid-beta oligomers (A&#946;o) that begin to accumulate in the human brain approximately 10 to 15 yr before the clinical symptoms become apparent. Many reports indicate that soluble A&#946;o correlate with memory deficits in AD models and humans. The A&#946;o-induced neurodegeneration observed in neuronal and brain slice cultures has been more challenging to reproduce in many animal models. The model of repeated A&#946;o infusions shown here overcome this issue and allow addressing two key domains for developing new disease modifying therapies: identify biological markers to diagnose early AD, and determine the molecular mechanisms underpinning A&#946;o-induced memory deficits at the onset of AD. Since soluble A&#946;o aggregate relatively fast into insoluble A&#946; fibrils that correlate poorly with the clinical state of patients, soluble A&#946;o are prepared freshly and injected once per day during six days to produce marked cell death in the hippocampus. We used cannula specially design for simultaneous infusions of A&#946;o and continuous infusion of A&#946;o antibody (6E10) in the hippocampus using osmotic pumps. This innovative in vivo method can now be used in preclinical studies to validate the efficiency of new AD therapies that might prevent the deposition and neurotoxicity of A&#946;o in pre-dementia patients.

To study the effects of A&#946;o in vivo, we developed a model based on repeated hippocampal infusions of soluble A&#946;o coupled with continuous infusion of A&#946;o antibody (6E10) in the hippocampus using osmotic pumps to counteract the neurotoxic effect of A&#946;o.

Decline in hippocampal-dependent explicit memory (memory for facts and events) is one of the earliest clinical symptom of Alzheimer&#39;s disease (AD). It ...

Pancreatic Duct Infusion: An Effective and Selective Method of Drug and Viral Delivery

The pancreas is a bifunctional organ with both endocrine and exocrine components. A number of pathologies can afflict the pancreas, including diabetes, pancreatitis, and pancreatic cancer. All three of these diseases mark active areas of study, not only to develop immediate therapy, but also to better understand their pathophysiology. There are few tools to further these areas of study. Pancreatic duct infusion is an important technique that can allow for lineage tracing, gene introduction, and cell line-specific targeting. The technique requires the intricate dissection of the second portion of the duodenum and ampulla, followed by the occlusion of the bile duct and the cannulation of the pancreatic duct. Although the technique is technically challenging at first, the applications are myriad. Ambiguity in the specifics of the procedure between groups highlighted the need for a standard protocol. This work describes the expression of a green fluorescent protein (GFP) within the pancreas after the pancreatic duct infusion of a viral vector expressing GFP versus a sham surgery. The infusion and therefore expression is specific to the pancreas, without expression present in any other tissue type.

Pancreatic duct infusion is an important technique that can allow for lineage tracing, gene introduction, and cell line-specific targeting. A pancreatic duct infusion technique for drug and viral delivery to pancreatic cells is presented here.

The pancreas is a bifunctional organ with both endocrine and exocrine components. A number of pathologies can afflict the pancreas, including diabetes, ...

Ileectomy-induced Bile Overaccumulation in Mouse Intestine

Intestinal resection is a common therapeutic approach for human diseases such as obesity, inflammatory bowel disease, Crohn's disease, and colon cancer that often results in severe short bowel syndrome-like adverse effects including bile acid diarrhea, dehydration, electrolyte disturbances, and nutrient malabsorption. Here we introduce a murine ileal resection model, termed ileectomy, to evaluate tissue communication and the maintenance of systemic homeostasis. After ileal resection, circulating blood is permanently devoid of the ileum-specific endocrine hormone fibroblast growth factor 15 (FGF15), which releases its endocrinal inhibition of bile acid synthesis in the liver. In combination with the increased production and abolished reabsorption of bile acids after removing the ileum, mice that underwent surgery suffer from bile salt overaccumulation in the intestine and associated diarrhea, morbidity, and mortality. Novel usage of the surgery model introduced in this study may provide mechanistic and functional insights into ileal control of systemic metabolic regulation in physiology and disease.

Small intestine-dependent bile acid reabsorption and feedback inhibition of hepatic bile acid synthesis is important for systemic homeostasis and health. In this study, we describe a mouse model for ileal resection to evaluate ileectomy-induced bile malabsorption, overaccumulation, and toxicity in mouse intestine.

Intestinal resection is a common therapeutic approach for human diseases such as obesity, inflammatory bowel disease, Crohn's disease, and colon cancer ...

Isometric Contractility Measurement of the Mouse Mesenteric Artery Using Wire Myography

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and drugs. It is widely used in many studies on the physiological functions of vascular smooth muscle, the pathogenesis of vascular diseases such as hypertension, and the development of smooth muscle relaxant drugs. The mouse is a widely used model animal with a large pool of disease models and genetically modified strains. We introduced this method to measure the isometric contraction of mouse mesenteric artery in detail. A 1.4-mm segment of mouse mesenteric resistance artery was isolated and mounted on a myograph chamber by passing two steel wires through its lumen. After equilibration and normalization steps, the vessel segment was potentiated by a high-K+ solution twice prior to the contraction assay. As an example of the application of this method in drug development, we measured the relaxant effect of a novel natural substance, neoliensinine, isolated from a Chinese herb, embryos of the lotus seed (Nelumbo nucifera Gaertn.) on mouse mesenteric arteries. The vessel segments mounted on the myograph chamber were stimulated with a high-K+ solution. When the force tension reached a stable sustained phase, cumulative doses of neoliensinine were added to the chamber. We found that neoliensinine had a dose-dependent relaxant effect on smooth muscle contraction, thus suggesting that it bears potential activity against hypertension. In addition, as the vessel segment can survive at least 4 hours after mounting and maintain contractility induced by the high-K+ solution for many times, we suggest that the wire myograph system may be used for the time-consuming process of drug screening.

The wire myograph technique is used to investigate vascular smooth muscle functions and screen new drugs. We report a detailed protocol for measuring the isometric contractility of the mouse mesenteric artery and for screening new relaxants of vascular smooth muscle.

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and ...