Name: induction of nephrotic syndrome in mice by retrobulbar injection of doxorubicin and prevention of volume retention by sustained release aprotinin
Uploaded: 2018-05-06T15:00:00
Description: Watch this Scientific Journal Video about Induction of Nephrotic Syndrome in Mice by Retrobulbar Injection of Doxorubicin and Prevention of Volume Retention by Sustained Release Aprotinin at JoVE.com

This study was supported by a grant from the German Research Foundation (DFG, AR 1092/2-1).

All methods were conducted according to the National Institutes of Health Guide for the Care and Use of Laboratory Animals and the German law for the welfare of animals, and they were approved by local authorities (Regierungspr&#228;sidium T&#252;bingen).
1. Induction of Experimental Nephrotic Syndrome by Doxorubicin Injection to the Retrobulbar Sinus
<ol>
	<li>Prepare a 0.5 mL syringe with a mounted 30G cannula by marking the stop position of the piston.</li>
	<li>Calculate injection volume...

<ol>
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W., Hemmingsen, S. C., Frokiaer, J., Nielsen, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Increased+expression+but+not+targeting+of+ENaC+in+adrenalectomized+rats+with+PAN-induced+nephrotic+syndrome.">Increased expression but not targeting of ENaC in adrenalectomized rats with PAN-induced nephrotic syndrome.</a> Am J Physiol Renal Physiol. 291 (1), F208-F217 (2006).</li><li>Artunc, 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=Serum-+and+glucocorticoid-inducible+kinase+1+in+doxorubicin-induced+nephrotic+syndrome.">Serum- and glucocorticoid-inducible kinase 1 in doxorubicin-induced nephrotic syndrome.</a> Am J Physiol Renal Physiol. 295 (6), F1624-F1634 (2008).</li><li>Zheng, 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=A+Mendelian+locus+on+chromosome+16+determines+susceptibility+to+doxorubicin+nephropathy+in+the+mouse.">A Mendelian locus on chromosome 16 determines susceptibility to doxorubicin nephropathy in the mouse.</a> Proc Natl Acad Sci U S A. 102 (7), 2502-2507 (2005).</li><li>Kimura, 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=Interstrain+differences+in+murine+daunomycin-induced+nephrosis.">Interstrain differences in murine daunomycin-induced nephrosis.</a> Nephron. 63 (2), 193-198 (1993).</li><li>Wang, Y., Wang, Y. P., Tay, Y. C., Harris, D. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Progressive+adriamycin+nephropathy+in+mice:+sequence+of+histologic+and+immunohistochemical+events.">Progressive adriamycin nephropathy in mice: sequence of histologic and immunohistochemical events.</a> Kidney Int. 58 (4), 1797-1804 (2000).</li><li>Svenningsen, 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=Plasmin+in+nephrotic+urine+activates+the+epithelial+sodium+channel.">Plasmin in nephrotic urine activates the epithelial sodium channel.</a> Journal of the American Society of Nephrology : JASN. 20 (2), 299-310 (2009).</li><li>Passero, C. J., Hughey, R. P., Kleyman, T. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+role+for+plasmin+in+sodium+homeostasis.">New role for plasmin in sodium homeostasis.</a> Curr Opin Nephrol Hypertens. 19 (1), 13-19 (2010).</li><li>Bohnert, B. N., 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=Aprotinin+prevents+proteolytic+epithelial+sodium+channel+(ENaC)+activation+and+volume+retention+in+nephrotic+syndrome.">Aprotinin prevents proteolytic epithelial sodium channel (ENaC) activation and volume retention in nephrotic syndrome.</a> Kidney Int. 93 (1), 159-172 (2018).</li><li>Pippin, J. W., 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=Inducible+rodent+models+of+acquired+podocyte+diseases.">Inducible rodent models of acquired podocyte diseases.</a> Am J Physiol Renal Physiol. 296 (2), F213-F229 (2009).</li><li>Bohnert, B. N., 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=Impact+of+phosphorus+restriction+and+vitamin+D-substitution+on+secondary+hyperparathyroidism+in+a+proteinuric+mouse+model.">Impact of phosphorus restriction and vitamin D-substitution on secondary hyperparathyroidism in a proteinuric mouse model.</a> Kidney Blood Press Res. 40 (2), 153-165 (2015).</li><li>Morton, D. B., Griffiths, P. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Guidelines+on+the+recognition+of+pain,+distress+and+discomfort+in+experimental+animals+and+an+hypothesis+for+assessment.">Guidelines on the recognition of pain, distress and discomfort in experimental animals and an hypothesis for assessment.</a> Vet Rec. 116 (16), 431-436 (1985).</li><li>Beath, S. 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=Plasma+aprotinin+concentrations+during+cardiac+surgery:+full-+versus+half-dose+regimens.">Plasma aprotinin concentrations during cardiac surgery: full- versus half-dose regimens.</a> Anesth Analg. 91 (2), 257-264 (2000).</li><li>Kanter, P. 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=Preclinical+toxicology+study+of+liposome+encapsulated+doxorubicin+(TLC+D-99):+comparison+with+doxorubicin+and+empty+liposomes+in+mice+and+dogs.">Preclinical toxicology study of liposome encapsulated doxorubicin (TLC D-99): comparison with doxorubicin and empty liposomes in mice and dogs.</a> In Vivo. 7 (1), 85-95 (1993).</li><li>Ma, L. J., Fogo, A. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Model+of+robust+induction+of+glomerulosclerosis+in+mice:+importance+of+genetic+background.">Model of robust induction of glomerulosclerosis in mice: importance of genetic background.</a> Kidney Int. 64 (1), 350-355 (2003).</li><li>Kren, S., Hostetter, T. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+course+of+the+remnant+kidney+model+in+mice.">The course of the remnant kidney model in mice.</a> Kidney Int. 56 (1), 333-337 (1999).</li><li>Mizuno-Horikawa, Y., Mizuno, S., Tamura, S., Kurosawa, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Advanced+glomerulosclerosis+is+reversible+in+nephrotic+mice.">Advanced glomerulosclerosis is reversible in nephrotic mice.</a> Biochem Biophys Res Commun. 284 (3), 707-713 (2001).</li><li>Friberger, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chromogenic+peptide+substrates.+Their+use+for+the+assay+of+factors+in+the+fibrinolytic+and+the+plasma+kallikrein-kinin+systems.">Chromogenic peptide substrates. Their use for the assay of factors in the fibrinolytic and the plasma kallikrein-kinin systems.</a> Scand J Clin Lab Invest Suppl. 162, 1-298 (1982).</li><li>Haerteis, 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=Plasma+kallikrein+activates+the+epithelial+sodium+channel+in+vitro+but+is+not+essential+for+volume+retention+in+nephrotic+mice.">Plasma kallikrein activates the epithelial sodium channel in vitro but is not essential for volume retention in nephrotic mice.</a> Acta Physiologica. , (2018).</li><li>Schork, 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=Association+of+Plasminuria+with+Overhydration+in+Patients+with+CKD.">Association of Plasminuria with Overhydration in Patients with CKD.</a> Clin J Am Soc Nephrol. 11 (5), 761-769 (2016).</li></ol>

Here, we demonstrate that doxorubicin injection via retrobulbar sinus injection induces experimental nephrotic syndrome in 129S1/SvImJ mice with proteinuria, sodium retention, hypoalbumenia and hyperlipidemia. However, there are two critical issues that have to be taken into account when using this model. Firstly, the model induction is strictly dose dependent and deviations of doxorubicin dose as small as 0.3 &#181;g/g affect the response of the mice15. When injected with a lower dose such as 14 ...

Nephrotic syndrome is characterized by heavy proteinuria, hypoalbuminemia, edema and hyperlipidemia, and can be regarded as the most extreme manifestation of proteinuric kidney disease. In rodents, experimental nephrotic syndrome can be induced by single injection of anthracyclines or puromycin which leads to podocyte damage and resembles human minimal change disease and focal segmental glomerulosclerosis (FSGS)1. After its first description in 1955 by Frenk et al.2, puromycin nucleoside nephrosis (PAN) in rats has become a standard model to investigate the pathophysiology of nephrotic syndrome in numerous studies3,4,5,6. In mice, the corresponding model can be induced by the anthracycline doxorubicin7. However, there is a strong strain-dependency that is genetically determined by at least two genetic loci8. In addition, there are differences in the proteinuric response and course of the nephrotic syndrome9,10. Using 129S1/SvImJ mice and rapid intravenous injection of doxorubicin via the retrobulbar sinus, proteinuria responses reach values that are sufficient to induce the typical features of nephrotic syndrome, particularly volume retention characterized by ascites and nearly sodium-free urine7. Sodium retention in experimental nephrotic syndrome has been presumed to be the result of activation of the epithelial sodium channel (ENaC) in the distal tubule by aberrantly filtered serine proteases such as plasmin causing proteolysis of its &#947;-subunit4,11,12. Recently, this concept was proven in nephrotic mice which were protected from proteolytic ENaC activation and sodium retention by treatment with the serine protease inhibitor aprotinin that was equally effective as the ENaC blocker amiloride13. To ensure continuous delivery to the distal tubule, aprotinin was administered via subcutaneously implanted sustained release pellets. Future studies are required to identify the serine proteases that are responsible for proteolytic ENaC activation in nephrotic syndrome which is thought to parallel the human situation. For this purpose, doxorubicin-induced nephrotic syndrome is a valuable model that can be used in wild-type mice or expanded to genetically engineered mice. Its advantages include low cost of the drug, lower complexity of management and good reproducibility14.
In this article, we demonstrate the induction of experimental nephrotic syndrome by rapid intravenous injection of doxorubicin to the retrobulbar sinus and implantation of sustained-release pellets containing aprotinin to inhibit urinary serine protease activity as measured with a chromogenic assay.

<table>
	<tbody>
		<tr>
			<td>supplies</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>BD Micro FINE + U-40 (0.30 mm x 8 mm)</td>
			<td>BD Deutschland GmbH, Heidelberg, Germany</td>
			<td>PZN: 07468060</td>
			<td>syring</td>
		</tr>
		<tr>
			<td>ETHILON*II (5/0, 16 mm, 3/8c, 45 cm)</td>
			<td>Johnson&#38;Johnson Medical GmbH, Ethicon Deutschland, Norderstedt, Germany)</td>
			<td>EH7823H</td>
			<td>suture</td>
		</tr>
		<tr>
			<td>Name</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>reagents</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>aprotinin (6000 KIU/mg)</td>
			<td>LOXO, Heidelberg, Germany</td>
			<td>CAS 9087-70-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Bepanthen, Augen- und Nasensalbe</td>
			<td>Bayer Vital GmbH, Leverkusen, Germany</td>
			<td>PZN: 1578681</td>
			<td>ointment</td>
		</tr>
		<tr>
			<td>Chromogenix S-2251</td>
			<td>HAEMOCHROM DIAGNOSTICA GmbH, Essen, Germany</td>
			<td>82 0332 39</td>
			<td>chromogenic substrate</td>
		</tr>
		<tr>
			<td>doxorubicin (2.0 &#181;g/&#181;L)</td>
			<td>Cell Pharm, Bad Vilbel, Germany</td>
			<td>CAS 25316-40-9</td>
			<td>doxorubicin</td>
		</tr>
		<tr>
			<td>isofluran CP (1 mL/mL)</td>
			<td>CP-Pharma, Burgdorf, Germany</td>
			<td>CAS 26675-46-7</td>
			<td>isofluran</td>
		</tr>
		<tr>
			<td>pellets with matrix-driven sustained release (custom-made)</td>
			<td>Innovative Research of America, Sarasota, FL</td>
			<td>X-999</td>
			<td>pellet</td>
		</tr>
		<tr>
			<td>Name</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>equipment</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>ELx808 Absorbance Mikroplate Reader</td>
			<td>BioTek, Bad Friedrichshall, Germany</td>
			<td>ELx808</td>
			<td>microplate reader</td>
		</tr>
		<tr>
			<td>MICROSTERIL - 436</td>
			<td>B.M.S., Trescore Balneario, Italy</td>
			<td>GAL/436</td>
			<td>sterilizer</td>
		</tr>
		<tr>
			<td>Hybridization oven/shaker</td>
			<td>GE Healthcare UK Limited, Amersham LIFE SCIENCE, Little Chalfont, UK</td>
			<td>RPN 2511</td>
			<td>heat chamber</td>
		</tr>
		<tr>
			<td>Thermo MAT Pro 10 W, 15x25 cm, Lucky Reptile</td>
			<td>Import Export Peter Hoch GmbH, Waldkirch, Germany</td>
			<td>61201</td>
			<td>mouse warming device</td>
		</tr>
	</tbody>
</table>

induction of nephrotic syndrome in mice by retrobulbar injection of doxorubicin and prevention of volume retention by sustained release aprotinin

Nephrotic syndrome is the most extreme manifestation of proteinuric kidney disease and characterized by heavy proteinuria, hypoalbuminemia, and edema due to sodium retention and hyperlipidemia. To study the pathophysiology of this syndrome, rodent models have been developed based on the injection of toxic substances such as doxorubicin causing podocyte damage. In mice, only few strains are susceptible to this model. In wildtype 129S1/SvImJ mice, the administration of doxorubicin by rapid intravenous injection to the retrobulbar sinus induces experimental nephrotic syndrome that features all the symptoms of human disease including sodium retention and edema. After the onset of proteinuria, mice exhibit increased urinary serine protease activity that leads to the activation of the epithelial sodium channel (ENaC) and sodium retention. Pharmacological inhibition of urinary serine proteases by the treatment with sustained release aprotinin abrogates ENaC activation and prevents sodium retention. This model is ideal to study the pathophysiology of proteasuria, i.e., the excretion of active serine proteases that cause ENaC activation by the proteolysis of its &#947;-subunit. This can be regarded as the primary mechanism of ENaC activation and sodium retention in proteinuric kidney disease.

After the induction of isoflurane narcosis, doxorubicin was rapidly injected via the left retrobulbar sinus. The entire volume of 7.25 &#181;L/g bw was injected without any resistance and extravasation proving correct intravenous location of the cannula. The mouse recovered from narcosis rapidly and had no impairment on that day and thereafter. Particularly, there was no sign of damage at the left eye. After doxorubicin injection, food and fluid intake dropped over the first 3 days due to...

Watch this Scientific Journal Video about Induction of Nephrotic Syndrome in Mice by Retrobulbar Injection of Doxorubicin and Prevention of Volume Retention by Sustained Release Aprotinin at JoVE.com

Induction of Nephrotic Syndrome in Mice by Retrobulbar Injection of Doxorubicin and Prevention of Volume Retention by Sustained Release Aprotinin

Here, we describe the induction of experimental nephrotic syndrome in 129S1/SvImJ mice by rapid retrobulbar injection of doxorubicin. We also treat nephrotic mice with sustained release pellets containing aprotinin to inhibit urinary serine protease activity and prevent sodium retention.

Nephrotic syndrome is the most extreme manifestation of proteinuric kidney disease and characterized by heavy proteinuria, hypoalbuminemia, and edema due ...

The overall goal of this mouse model of experimental nephrotic syndrome is to feature all the facets of the syndrome known from human patients, most importantly, sodium retention and edema formation. This model can help to elucidate the mechanisms of sodium retention in nephrotic syndrome. As will be shown in this article, sodium retention is caused by the excretion of active serum proteases in the urine, which we have termed proteasuria.The main advantages of this model are that it is easy to induce and that it features all of the facets of human nephrotic syndrome and chronic kidney disease. During the implantation segment of the protocol, Dr.Bohnert, a research fellow, will demonstrate this technique. To begin, warm the doxorubicin in a 37 degrees Celsius chamber.Next, prepare the injection syringe. Mark the stop position of the piston on the syringe to deliver the required dose of doxorubicin using a two microgram per microliter solution. Then, zero the mass of a prepared syringe and load it into the syringe to the marked point.For confirmation of the volume, re-weigh the syringe. This injection has to take place approximately 30 seconds after narcosis. After anesthetizing the mouse, position it at right lateral recumbency with its head facing to the operator's injection hand.Then, carefully protrude the left eyeball using gentle pressure dorsal and ventral to the eye. Next, insert the cannula into the left retrobulbar sinus from the inner-eye angle, without making contact with the eyeball. Now, slightly tilt the syringe and inject the bolus in one stroke.There should be no resistance or signs of extravasation, such as exophthalmus or leakage from the injection site. After re-injection, recheck for correct intravenous injection. There should be no signs of extravasation, as mentioned before.Then, re-weigh the syringe and calculate the actual administered dose of doxorubicin. To begin, prepare the required items for the surgery on a drape. A pair of hair scissors, a pair of skin preparation scissors, a scalpel, surgical tweezers, two pairs of tissue tweezers, a needle holder, and 15 centimeters of non-resorbable MONOFIL suture.Place a warming device on the surgical stage, cover it with a layer of gauze, and then place an anesthetized mouse, prone, onto the gauze. Now, apply ophthalmic ointment and remove about 0.5 square centimeters of hair centrally from the back, using scissors. Then, disinfect the skin with alcohol.By minimizing the hair removal, the wound will have natural protection. Now, make an incision in the cranial caudal direction that is about five millimeters long. Then, by bluntly dissecting the subcutaneous connective tissue, make a left lateral pouch about one centimeter deep.Next, remove a 10-day release pellet from its dry container and place it into the bottom of the pouch in a planar position. Then, close the skin with a few sutures. Make the thread ends very short so it will be difficult for the mouse to open the sutures by gnawing.Now, have the mice recover from the surgery alone to minimize post-operative distress and suture gnawing. Monitor the mouse until it has regained sternal recumbency. Collect urine from the mice on a daily basis in the morning within about two hours after subjective dawn.Massage the bladder of the mouse to collect as much urine as possible in a 1.5 milliliter tube. At the same time, look for the development of ascites. Check for an increase of abdominal circumference or for overhanging flanks.Then, weigh the mouse, the food pellets, and the drinking bottle. Later, measure proteasuria based on the proteolytic activity of urine samples, using S2251 as a chromogenic substrate. Do not use S2251 working solution if it has a strong shade of yellow.Thaw the urine samples at room temperature and for the assay, prepare a 96-well plate that can be measured by a plate reader. For each sample, add three microliters of urine to two wells. Then, add three microliters of PBS or aprotinin solution to each well.Then, add 50 microliters of substrate working solution to each well. After all the samples have been set up, cover the plate with a plate sealer and incubate the plate at 37 degrees Celsius for an hour. Then, measure the optical density of each well at 450 nanometers using a microplate reader.After injecting mice with doxorubicin, food and fluid intake dropped over the first three days due to a general toxic effect of doxorubicin, but recovered thereafter. By five days after injection, the mice started showing signs of marked proteinuria, followed by a massive decline of urinary sodium excretion despite adequate food intake. Three days after the doxorubicin injection, a mouse was implanted with an aprotinin-containing pellet and another was implanted with a placebo pellet.In these mice, sodium retention and body weight gain were only experienced by the placebo-treated mouse. Next, the effect of aprotinin on urinary serine protease activity was measured with a chromogenic assay using urine samples from the implanted mice. Serine protease activity increased rapidly in the placebo-treated mice, paralleling the onset of proteinuria, whereas urinary serine protease activity were completely inhibited in the aprotinin-treated nephrotic mice.Once mastered, this model is useful to study the mechanisms of sodium retention in nephrotic syndrome, which center around the excretion of active serine proteases in the urine or proteasuria. This leads to activation of the epithelial sodium channel ENaC in the distal tubule by proteolysis. This model resembles human nephrotic syndrome caused by protocyte loss as observed in focal segmental glomerulosclerosis.In the course of the model, mice develop progressive renal failure with typical consequences such as secondary hypo-parathyroidism and renal anemia, recapitulating all stages of chronic kidney disease.

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Cardiac Stress Test Induced by Dobutamine and Monitored by Cardiac Catheterization in Mice

Dobutamine is a &beta;-adrenergic agonist with an affinity higher for receptor expressed in the heart (&beta;1) than for receptors expressed in the arteries (&beta;2). When systemically administered, it increases cardiac demand. Thus, dobutamine unmasks abnormal rhythm or ischemic areas potentially at risk of infarction. 
Monitoring of heart function during a cardiac stress test can be performed by either ecocardiography or cardiac catheterization. The latter is an invasive but more accurate and informative technique that the former.
Cardiac stress test induced by dobutamine and monitored by cardiac catheterization accomplished as described here allows, in a single experiment, the measurement of the following hemodynamic parameters: heart rate (HR), systolic pressure, diastolic pressure, end-diastolic pressure, maximal positive pressure development (dP/dtmax) and maximal negative pressure development (dP/dtmin), at baseline conditions and under increasing doses of dobutamine.
As expected, in normal mice we observed a dobutamine dose-related increase in HR, dP/dtmax and dP/dtmin. Moreover, at the highest dose tested (12 ng/g/min) the cardiac decompensation of high fat diet-induced obese mice was unmasked.

We describe the protocol to perform a cardiac stress test induced by dobutamine and monitored by cardiac catheterization in normal mice. Also we show its application to unmask subclinical cardiac disease in high fat diet-induced obese mice.

Dobutamine is a &beta;-adrenergic agonist with an affinity higher for receptor expressed in the heart (&beta;1) than for receptors expressed in the ...

Retinal Detachment Model in Rodents by Subretinal Injection of Sodium Hyaluronate

Subretinal injection of sodium hyaluronate is a widely accepted method of inducing retinal detachment (RD). However, the height and duration of RD or the occurrence of subretinal hemorrhage can affect photoreceptor cell death in the detached retina. Hence, it is advantageous to create reproducible RDs without subretinal hemorrhage for evaluating photoreceptor cell death. We modified a previously reported method to create bullous and persistent RDs in a reproducible location with rare occurrence of subretinal hemorrhage. The critical step of this modified method is the creation of a self-sealing scleral incision, which can prevent leakage of sodium hyaluronate after injection into the subretinal space. To make the self-sealing scleral incision, a scleral tunnel is created, followed by scleral penetration into the choroid with a 30 G needle. Although choroidal hemorrhage may occur during this step, astriction with a surgical spear reduces the rate of choroidal hemorrhage. This method allows a more reproducible and reliable model of photoreceptor death in diseases that involve RD such as rhegmatogenous RD, retinopathy of prematurity, diabetic retinopathy, central serous chorioretinopathy, and age-related macular degeneration (AMD).

Creating experimental retinal detachments with a reproducible and sustained height of detachment, and without subretinal hemorrhage, is important for studying the pathophysiology of photoreceptor cell loss in retinal disease and evaluating potential therapeutic interventions. Here, we report such a method in detail.

Subretinal injection of sodium hyaluronate is a widely accepted method of inducing retinal detachment (RD). However, the height and duration of RD or the ...

Experimental Glaucoma Induced by Ocular Injection of Magnetic Microspheres

Progress in understanding the pathophysiology, and providing novel treatments for glaucoma is dependent on good animal models of the disease. We present here a protocol for elevating intraocular pressure (IOP) in the rat, by injecting magnetic microspheres into the anterior chamber of the eye. The use of magnetic particles allows the user to manipulate the beads into the iridocorneal angle, thus providing a very effective blockade of fluid outflow from the trabecular meshwork. This leads to long-lasting IOP rises, and eventually neuronal death in the ganglion cell layer (GCL) as well as optic nerve pathology, as seen in patients with the disease. This method is simple to perform, as it does not require machinery, specialist surgical skills, or many hours of practice to perfect. Furthermore, the pressure elevations are very robust, and reinjection of the magnetic microspheres is not usually required unlike in some other models using plastic beads. Additionally, we believe this method is suitable for adaptation for the mouse eye.

We present a method for inducing elevated intraocular pressure (IOP), by injecting magnetic microspheres into the rat eye, to model glaucoma. This leads to strong pressure rises, and extensive neuronal death. This protocol is easy to perform, does not require repeat injections, and produces stable long-lasting IOP rises.

Progress in understanding the pathophysiology, and providing novel treatments for glaucoma is dependent on good animal models of the disease. We present ...

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 ...

Real-time Pressure-volume Analysis of Acute Myocardial Infarction in Mice

Acute myocardial infarction can lead to acute heart failure and cardiogenic shock. The evaluation of hemodynamics is critical for the evaluation of any potential therapeutic approach directed against acute left ventricular (LV) dysfunction. Current imaging modalities (e.g., echocardiography and magnetic resonance imaging) have several limitations since data on LV pressure cannot directly be measured. LV catheterization in mice undergoing coronary artery occlusion could serve as a novel method for a real-time evaluation of LV function.
At the beginning of the procedure, mice were anesthetized followed by endotracheal intubation. For LV catheterization, the right carotid artery was exposed via middle-neck incision. The catheter was introduced and placed into the LV cavity. Left thoracotomy was conducted and the left main coronary artery (LCA) was ligated. To induce reperfusion, the suture was released after 45 min. Pressure-volume data was recorded at all times.
Ligation of the LCA caused a decrease in LV systolic function as evidenced by a 30% reduction in stroke volume, LV ejection fraction (EF), and cardiac output. Maximum dP/dt as a parameter for LV contractility was also significantly reduced and diastolic function was severely impaired (minimum dP/dt -40%). Reperfusion over a period of 20 min did not lead to a complete recovery of LV function.
Real-time pressure-volume analysis served as a valid procedure for monitoring cardiac function during acute myocardial infarction in mice. Maintaining stable anesthesia and a standardized surgical approach was crucial to ensure valid results. As the early phase of acute myocardial infarction is critical for morbidity and mortality, the delineated method could be beneficial for preclinical evaluation of new strategies for cardioprotection.

Acute myocardial infarction in mice induces acute but incompletely characterized changes in left ventricular (LV) function. LV catheterization in mice undergoing coronary artery occlusion serves as a novel method for a real-time evaluation of LV function.

Acute myocardial infarction can lead to acute heart failure and cardiogenic shock. The evaluation of hemodynamics is critical for the evaluation of any ...

A Model of Glaucoma Induced by Circumlimbal Suture in Rats and Mice

The circumlimbal suture is a technique for inducing experimental glaucoma in rodents by chronically elevating intraocular pressure (IOP), a well-known risk factor for glaucoma. This protocol demonstrates a step-by-step guide on this technique in Long Evans rats and C57BL/6 mice. Under general anesthesia, a "purse-string" suture is applied on the conjunctiva, around the equator and behind the limbus of the eye. The fellow eye serves as an untreated control. Over the duration of our study, which was a period of 8 weeks for rats and 12 weeks for mice, IOP remained elevated, as measured regularly by rebound tonometry in conscious animals without topical anesthesia. In both species, the sutured eyes showed electroretinogram features consistent with preferential inner retinal dysfunction. Optical coherence tomography showed selective thinning of the retinal nerve fiber layer. Histology of the rat retina in cross-section found reduced cell density in the ganglion cell layer, but no change in other cellular layers. Staining of flat-mounted mouse retinae with a ganglion cell specific marker (RBPMS) confirmed ganglion cell loss. The circumlimbal suture is a simple, minimally invasive and cost-effective way to induce ocular hypertension that leads to ganglion cell injury in both rats and mice.

Chronic ocular hypertension is induced by applying a circumlimbal suture in rats and mice, leading to functional and structural deterioration of the retinal ganglion cells consistent with glaucoma.

The circumlimbal suture is a technique for inducing experimental glaucoma in rodents by chronically elevating intraocular pressure (IOP), a well-known ...

Biventricular Assessment of Cardiac Function and Pressure-Volume Loops by Closed-Chest Catheterization in Mice

Assessment of cardiac function is essential to conduct cardiovascular and pulmonary-vascular preclinical research. Pressure-volume loops (PV loops) generated by recording both pressure and volume during cardiac catheterization are vital when assessing both systolic and diastolic cardiac function. Left and right heart function are closely related, reflected in ventricular interdependence. Thus, recording biventricular function in the same animal is important to get a complete assessment of cardiac function. In this protocol, a closed chest approach to cardiac catheterization consistent with the way catheterization is performed in patients is adopted in mice. While challenging, the closed chest strategy is a more physiological approach, because opening the chest results in major changes in preload and afterload that create artifacts, most notably a fall in systemic blood pressure. While high-resolution echocardiography is used to assess rodents, cardiac catheterization is invaluable, particularly when assessing diastolic pressures in both ventricles.
Described here is a procedure to perform invasive, closed chest, sequential left and right ventricular pressure-volume (PV) loops in the same animal. PV loops are acquired using&#160;admittance technology with a mouse pressure-volume catheter and pressure-volume system acquisition. The procedure is described, beginning with the neck dissection, which is required to access the right jugular vein and the right carotid artery, to the insertion and positioning of the catheter, and finally the data acquisition. Then, the criteria required to ensure the acquisition of high-quality PV loops are discussed. Finally, the analysis of the left and right ventricular PV loops and the different hemodynamic parameters available to quantify systolic and diastolic ventricular function are briefly described.

Presented here is a protocol to assess biventricular heart function in mice by generating pressure-volume (PV) loops from the right and left ventricle in the same animal using closed chest catheterization. The focus is on the technical aspect of surgery and data acquisition.

Assessment of cardiac function is essential to conduct cardiovascular and pulmonary-vascular preclinical research. Pressure-volume loops (PV loops) ...

Induction of Myocardial Infarction and Myocardial Ischemia-Reperfusion Injury in Mice

Acute myocardial infarction is a common cardiovascular disease with high mortality. Myocardial reperfusion injury can counteract the beneficial effects of heart reflow and induce secondary myocardial injury. A simple and reproducible model of myocardial infarction and myocardial ischemia-reperfusion injury is a good tool for researchers. Here, a customizable method to create a myocardial infarction (MI) model and MIRI by precision ligation of the left anterior descending coronary artery (LAD) through micromanipulation is described. Accurate and reproducible ligature positioning of the LAD helps obtain consistent results for heart injury. ST-segment changes can help to identify model accuracy. The serum level of cardiac troponin T (cTnT) is used to assess the myocardial injury, cardiac ultrasound is employed to evaluate the myocardial systolic function, and Evans-Blue/triphenyl tetrazolium chloride staining is used to measure infarct size. In general, this protocol reduces procedure duration, ensures controllable infarct size, and improves mouse survival.

Here we describe a simple and reproducible method that can induce myocardial infarction or myocardial ischemia-reperfusion injury in mice by precision ligation of the left anterior descending coronary artery through micromanipulation.

Acute myocardial infarction is a common cardiovascular disease with high mortality. Myocardial reperfusion injury can counteract the beneficial effects of ...

Induction of Intestinal Inflammation by Adoptive Transfer of CBir1 TCR Transgenic CD4+ T Cells to Immunodeficient Mice

With the increase of incidence, inflammatory bowel diseases (IBD), which are chronic diseases affecting the gastrointestinal tract, impose a considerable health and financial burden on individuals and society. Therefore, it is critical to investigate the mechanisms underlying the pathogenesis and development of IBD. Here, a gut microbiota antigen-specific T cell transfer colitis model is described. CBir1 flagellin has been recognized as the immunodominant gut bacterial antigen in experimental colitis and patients with Crohn&#39;s disease. CBir1 TCR transgenic na&#970;ve CD4+ T cells, specific to CBir1 flagellin, can induce chronic colitis after adoptive transfer into immune-deficient Rag1-/- mice. The disease severity is assessed by histopathology. The CD4+ T cell phenotypes in colonic lamina propria are also determined. This model closely resembles the development of IBD, which provides an ideal murine model for investigating the mechanisms driving the pathogenesis of IBD and testing the potential drugs for treating IBD.

Induction of Intestinal Inflammation by Adoptive Transfer of CBir1 TCR Transgenic CD4+ T Cells to Immunodeficient Mice

In this protocol, a gut microbiota antigen-specific T cell adoptive transfer colitis model is described. CD4+ T cells are isolated from CBir1 TCR transgenic mice. These are specific for an immunodominant gut microbiota antigen CBir1 flagellin, which is transferred into recipient Rag1-/- mice, leading to intestinal inflammation.

With the increase of incidence, inflammatory bowel diseases (IBD), which are chronic diseases affecting the gastrointestinal tract, impose a considerable ...

Modified Arteriovenous Fistula Surgery to Establish the RV Volume Overload Mouse Model

Establishment and Confirmation of a Postnatal Right Ventricular Volume Overload Mouse Model

Right ventricular (RV) volume overload (VO) is common in children with congenital heart disease. In view of distinct developmental stages,the RV myocardium may respond differently to VO in children compared to adults. The present study aims to establish a postnatal RV VO model in mice using a modified abdominal arteriovenous fistula. To confirm the creation of VO and the following morphological and hemodynamic changes of the RV, abdominal ultrasound, echocardiography, and histochemical staining were performed for 3 months. As a result, the procedure in postnatal mice showed an acceptable survival and fistula success rate. In VO mice, the RV cavity was enlarged with a thickened free wall, and the stroke volume was increased by about 30%-40% within 2 months after surgery. Thereafter, the RV systolic pressure increased, corresponding pulmonary valve regurgitation was observed, and small pulmonary artery remodeling appeared. In conclusion, modified arteriovenous fistula (AVF) surgery is feasible to establish the RV VO model in postnatal mice. Considering the probability of fistula closure and elevated pulmonary artery resistance, abdominal ultrasound and echocardiography must be performed to confirm the model status before application.

Author Spotlight: Establishment and Confirmation of a Postnatal Right Ventricular Volume Overload Mouse Model  

This protocol presents the establishment and confirmation of a postnatal right ventricular volume overload (VO) model in mice with abdominal arteriovenous fistula (AVF), which can be applied to investigate how VO contributes to postnatal heart development.