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 of doxorubicin for male (7.25 &#181;L/g body weight (bw) equal to 14.5 &#181;g/g bw doxorubicin) and female mice (6.9 &#181;L/g bw equal to 13.8 &#181;g/g bw doxorubicin) according to the body weight from the morning. 
	NOTE: The given dose is appropriate for induction of nephrotic syndrome. Minor changes in dosage lead to a crucial different course of nephropathy reaching from mild chronic kidney disease with only small changes in glomerular filtration rate (12.6 &#181;g/g bw doxorubicin) to acute kidney failure (15.4 &#181;g/g bw doxorubicin)7,15.</li>
	<li>Warm the calculated amount of doxorubicin solution (2 &#181;g/&#181;L) in a 37 &#176;C warm chamber. 
	Caution: Doxorubicin is harmful if swallowed and can cause cancer. Always wear gloves if working with doxorubicin and avoid any skin contact.</li>
	<li>Prefill the syringe with doxorubicin solution until the marking point and set the balance to zero. Fill the syringe with the injection volume and check the volume by weighing the syringe.</li>
	<li>Narcotize the mouse deeply with 5 vol% isoflurane using a vaporizer and oxygen flow of 2 L/min.
	<ol>
		<li>Do not use ointment on the eyes prior to the injection. The operator needs a clear view of the orbital cavity for performing a safe and successful retrobulbar injection.</li>
		<li>Assess the level of anesthesia by pedal reflex and adjust anesthetic delivery if necessary before starting injection.</li>
	</ol>
	</li>
	<li>Place the mouse at a right lateral recumbency with its back facing to the operator&#39;s body and its head facing to the operator&#39;s injection hand. 
	NOTE: The procedure is described for a right-handed person, for left-handed persons performing the injection with the left hand it is easier to do the position and injection reversed right to left.</li>
	<li>Carefully protrude the mouse&#39;s left eyeball from the eye socket by applying gentle pressure to the skin, dorsal and ventral to the eye.</li>
	<li>Puncture the left retrobulbar sinus from the inner eye angle (medial palpebral commissure). Avoid any contact with the mouse&#180;s eyeball.</li>
	<li>Slightly tilt the syringe and inject entire volume in one go. Make sure that the volume is injected without any resistance and without any signs of extravasation such as exopthalmus or leakage from the injection site.</li>
	<li>Since doxorubicin is a highly toxic substance, check well-being at least once a day by using a score-sheet according to Morton and Griffiths et al.16 and pay special attention to the injection site. If any signs of extravasation like exopthalmus, impaired eyelid closure or any signs of necrosis like swelling or skin lesions occure after injection or in the following days, the mouse should be euthanized.</li>
</ol>
2. Implantation of Sustained-Release Pellets Containing Aprotinin
<ol>
	<li>Order pellets with the desired dose per day and release duration in advance. In case of aprotinin, choose a dose of 1 mg per day to be released over 10 days. 
	NOTE: In this study, the aprotinin pellets contain a dose of 10 mg.
	<ol>
		<li>Store the pellets under dry conditions and avoid any exposure to humidity.</li>
	</ol>
	</li>
	<li>Prepare required items for the surgery, including 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 cm monofile suture non resorbable.
	<ol>
		<li>Sterilize the instruments using a heat sterilizer for 5 min at 240 &#176;C. Before using the instruments, wait for 5 min until they reach room temperature.
		<ol>
			<li>Avoid any contact of sterilized instrument tips to nonsterile surfaces.</li>
			<li>Avoid skin burn by hot instruments.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Narcotize mouse with isoflurane 5 vol% followed by 1.5 vol% using a vaporizer and oxygen flow of 2 L/min.</li>
	<li>Place the mouse in a prone position on a warming device covered with a layer of gauze to avoid thermal injuries to the mouse. Surface temperature is about 37 &#176;C.</li>
	<li>Protect the eyes with ointment.</li>
	<li>Remove the hair on the middle back in an area of about 0.5 cm2 using scissors or a hair trimmer and disinfect the hairless skin with a disinfectant suitable for skin disinfection. Remove as less hair as possible so it stays more difficult for the mouse to reach the wound and thread ends later and to keep body temperature.</li>
	<li>Incise the hairless skin with a scalpel in cranio-caudal direction in a length of about 5 mm. Prepare a left lateral pouch of about 1 cm depth in the subcutaneous connective tissue using a blunt preparation.
	<ol>
		<li>Assess the level of anesthesia by pedal reflex and adjust anesthetic delivery if necessary before starting surgery.</li>
	</ol>
	</li>
	<li>Insert one 10-day release pellet into the prepared left lateral pouch using sterile tissue tweezers. Leave the pellet at the bottom of the pouch in a planar position.
	<ol>
		<li>Avoid any contact of the pellet to fluid and humidity till placed in the prepared pouch.</li>
	</ol>
	</li>
	<li>Close the skin with 2-3 sutures. Only leave very short thread ends to make it more difficult for the mouse to open the sutures by gnawing.</li>
	<li>Place the mice individually to reduce postoperative distress and to prevent opening of the sutures by gnawing. Keep the mouse in view until it has regained sufficient consciousness after narcosis. 
	NOTE: There is no need for postoperative pain management since this intervention is well tolerated without any signs of discomfort or pain.&#160;Alternatively we recommend topical analgesics, e.g. a drop of bupivacaine on the incision prior to closure which would provide up to 8 h of analgesia.</li>
</ol>
3. Assessment for Model Induction, Signs of Nephrotic Syndrome and well-being
<ol>
	<li>Collect morning urine (08:00 am) into a reaction cup (1.5 mL) every day from the injection day by massaging the bladder.
	<ol>
		<li>Measure proteinuria by using Bradford protein assay and normalize to creatinine. 
		NOTE: For induction of nephrotic syndrome, proteinuria should reach a threshold of 120 mg/mg creatinine between day 7 and 10 after doxorubicin injection.</li>
	</ol>
	</li>
	<li>Look for the development of ascites. Check for increase of abdominal circumference or overhanging flanks.</li>
	<li>Weigh the mouse, the food pellets and the drinking bottle in the morning (08:00 am) every day.</li>
	<li>Check well-being at least once a day by using a score-sheet according to Morton and Griffiths et al.16</li>
</ol>
4. Measurement of Urinary Serine Protease with a Chromogenic Assay
<ol>
	<li>Prepare substrate working solution by adding 15 mL of sterile phosphate buffered saline (PBS) to a bottle of 25 mg of lyophilised chromogenic substrate S-2251, yielding a concentration of 2 mM. Dissolve aprotinin in PBS to obtain an aprotinin solution with a concentration of 2 mg/mL.
	<ol>
		<li>Store prepared solutions at -20 &#176;C. This significantly slows the auto-degradation of S-2251. Do not use old solutions with a strong shade of yellow.</li>
	</ol>
	</li>
	<li>Use freshly prepared or thawed substrate working solution and warm it in a 37 &#176;C heat chamber.</li>
	<li>Thaw urine samples at room temperature.
	<ol>
		<li>Prevent protease degradation by avoiding repeated thawing and freezing. Store urine samples at -20 &#176;C.</li>
	</ol>
	</li>
	<li>Use a 96 microwell plate suitable for photometric measurement. Add 3 &#181;L of undiluted urine in each of two wells and add 50 &#181;L of substrate working solution with 3 &#181;L of either PBS or aprotinin solution to the wells. Cover the plate with a plate sealer.</li>
	<li>Incubate the covered microwell plate for 60 min in a 37 &#176;C heat chamber.</li>
	<li>Measure the optical density of each well at 450 nm using a microplate reader.</li>
	<li>Take the difference between the OD without aprotinin and with aprotinin as urinary aprotinin-sensitive serine protease activity. 
	NOTE: Measurement of a paired sample with and without aprotinin increases specificity of the assay since the substrate could also be cleaved by other proteases that do not play a pathophysiological role.</li>
</ol>

<ol>
	<li>Lee, V. W., 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=Adriamycin+nephropathy:+a+model+of+focal+segmental+glomerulosclerosis.">Adriamycin nephropathy: a model of focal segmental glomerulosclerosis.</a> Nephrology (Carlton). 16 (1), 30-38 (2011).</li><li>Frenk, S., Antonowicz, I., Craig, J. M., Metcoff, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+nephrotic+syndrome+induced+in+rats+by+aminonucleoside;+renal+lesions+and+body+electrolyte+composition.">Experimental nephrotic syndrome induced in rats by aminonucleoside; renal lesions and body electrolyte composition.</a> Proc Soc Exp Biol Med. 89 (3), 424-427 (1955).</li><li>Ichikawa, I., 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=Role+for+intrarenal+mechanisms+in+the+impaired+salt+excretion+of+experimental+nephrotic+syndrome.">Role for intrarenal mechanisms in the impaired salt excretion of experimental nephrotic syndrome.</a> J Clin Invest. 71, (1983).</li><li>Deschenes, G., Wittner, M., Stefano, A., Jounier, S., Doucet, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Collecting+duct+is+a+site+of+sodium+retention+in+PAN+nephrosis:+a+rationale+for+amiloride+therapy.">Collecting duct is a site of sodium retention in PAN nephrosis: a rationale for amiloride therapy.</a> J Am Soc Nephrol. 12 (3), 598-601 (2001).</li><li>Lourdel, 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=Hyperaldosteronemia+and+activation+of+the+epithelial+sodium+channel+are+not+required+for+sodium+retention+in+puromycin-induced+nephrosis.">Hyperaldosteronemia and activation of the epithelial sodium channel are not required for sodium retention in puromycin-induced nephrosis.</a> J Am Soc Nephrol. 16 (12), 3642-3650 (2005).</li><li>Seigneux, S., Kim, S. 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>

The authors have nothing to disclose.

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...

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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 ...

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8.3K Views.  University Hospital Tübingen. 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.

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

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 ...

Induction of Accelerated Atherosclerosis in Mice: The "Wire-Injury" Model

Atherosclerosis is a proliferative fibro-inflammatory disease developing in the arterial wall, inducing a deficient blood flow or a lack of blood flow. Moreover, by rupture of the defective vascular wall, atherosclerosis induces occlusive thrombus formation, which represents the main cause of myocardial infarction or stroke and the most frequent cause of death. Despite the advances in the cardiovascular field, many questions remain unanswered, and additional basic research is essential to improve our understanding of the molecular mechanisms during atherosclerosis and its effects. Due to limited clinical studies, there is a need for representative animal models recreating atherosclerotic conditions such as neointima formation after stent implantation, balloon angioplasty, or endarterectomy. Since the mouse presents many advantages and is the most frequently used model for studying molecular processes, the current study proposes an invasive procedure of endothelial denudation, also known as the wire-injury model, which is representative of the human condition of neointima formation in arteries after revascularization procedures.

This study describes an invasive procedure for the induction of accelerated atherosclerosis in mice. In comparison to other methods using electric- or cryo-induced injury, mechanical-induced injury mimics the human condition of restenosis after revascularization therapies and is ideal for the study of the molecular mechanisms involved.

Atherosclerosis is a proliferative fibro-inflammatory disease developing in the arterial wall, inducing a deficient blood flow or a lack of blood flow. ...

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 ...

Assessment of Respiratory Function in Conscious Mice by Double-chamber Plethysmography

Air volume changes created by a conscious subject breathing spontaneously within a body box are at the basis of plethysmography, a technique used to non-invasively assess some features of the respiratory function in humans as well as in laboratory animals. The present article focuses on the application of the double-chamber plethysmography (DCP) in small animals. It provides background information on the methodology as well as a detailed step-by-step procedure to successfully assess respiratory function in conscious, spontaneously breathing animals in a non-invasive manner. The DCP can be used to monitor the respiratory function of multiple animals in parallel, as well as to identify changes induced by aerosolized substances over a chosen time period and in a repeated manner. Experiments on control and allergic mice are used herein to demonstrate the utility of the technique, explain the associated outcome parameters, as well as to discuss the related advantages and shortcomings. Overall, the DCP provides valid and theoretically sound readouts that can be trusted to evaluate the respiratory function of conscious small animals both at baseline and after challenges with aerosolized substances.

The objective of the present article is to provide a detailed description of the recommended procedures to evaluate respiratory function in conscious mice by double-chamber plethysmography.

Air volume changes created by a conscious subject breathing spontaneously within a body box are at the basis of plethysmography, a technique used to ...

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 ...

Standardized Hemorrhagic Shock Induction Guided by Cerebral Oximetry and Extended Hemodynamic Monitoring in Pigs

Hemorrhagic shock ranks among the main reasons for severe injury-related death. The loss of circulatory volume and oxygen carriers can lead to an insufficient oxygen supply and irreversible organ failure. The brain exerts only limited compensation capacities and is particularly at high risk of severe hypoxic damage.This article demonstrates the reproducible induction of life-threatening hemorrhagic shock in a porcine model by means of calculated blood withdrawal. We titrate shock induction guided by near-infrared spectroscopy&#160;and extended hemodynamic monitoring to display systemic circulatory failure, as well as cerebral microcirculatory oxygen depletion. In comparison to similar models that primarily focus on predefined removal volumes for shock induction, this approach highlights a titration by means of the resulting failure of macro- and microcirculation.

Hemorrhagic shock is a severe complication in seriously injured patients, which leads to life-threatening oxygen undersupply. We present a standardized method to induce hemorrhagic shock via blood withdrawal in pigs that is guided by hemodynamics and microcirculatory cerebral oxygenation.

Hemorrhagic shock ranks among the main reasons for severe injury-related death. The loss of circulatory volume and oxygen carriers can lead to an ...

Osteoarthritis Pain Model Induced by Intra-Articular Injection of Mono-Iodoacetate in Rats

The current animal models of osteoarthritis (OA) can be divided into spontaneous models and induced models, both of which aim to simulate the pathophysiological changes of human OA. However, as the main symptom in the late stage of OA, pain affects the patients&#39; daily life, and there are not many available models. The mono-iodoacetate (MIA)-induced model is the most widely used OA pain model, mainly used in rodents. MIA is an inhibitor of glyceraldehyde-3-phosphate dehydrogenase, which causes chondrocyte death, cartilage degeneration, osteophyte, and measurable changes in animal behavior. Besides, expression changes of matrix metalloproteinase (MMP) and pro-inflammatory cytokines (IL1 &#946; and TNF &#945;) can be detected in the MIA-induced model. Those changes are consistent with OA pathophysiological conditions in humans, indicating that MIA can induce a measurable and successful OA pain model. This study aims to describe the methodology of intra-articular injection of MIA in rats and discuss the resulting pain-related behaviors and histopathological changes.

This study describes the method of intra-articular injection of mono-iodoacetate in rats and discusses the resulting pain-related behaviors and histopathological changes, which provide references for future applications.