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 JoVE Biology

Murine Colitis Modeling using Dextran Sulfate Sodium (DSS)

1, 2, 2

1Department of Cancer Biology, Vanderbilt University, 2Departments of Medicine and Cancer Biology, Vanderbilt University

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    Summary

    Dextran sulfate sodium (DSS) administered in the drinking water is an established murine inflammatory injury model of acute colitis. This protocol outlines the method for DSS treatment and the preparation of tissues.

    Date Published: 1/19/2010, Issue 35; doi: 10.3791/1652

    Cite this Article

    Whittem, C. G., Williams, A. D., Williams, C. S. Murine Colitis Modeling using Dextran Sulfate Sodium (DSS). J. Vis. Exp. (35), e1652, doi:10.3791/1652 (2010).

    Abstract

    Colitis can occur from viral or bacterial infections, ischemic insult, or autoimmune disorders; most notably Ulcerative Colitis and the colonic variant of Crohn’s Disease - Crohn’s Colitis. Acute colitis may present with abdominal pain and distention, malabsorption, diarrhea, hematochezia and mucus in the stool. We are beginning to understand the complex interactions between the environment, genetics, and epithelial barrier dysfunction in Inflammatory Bowel Disease and animal models of colitis have been essential in advancing our understanding of this disease. One popular model involves supplementing the drinking water of mice with low-molecular weight Dextran Sodium Sulfate (DSS), resulting in epithelial damage and a robust inflammatory response in the colon lasting several days 1.Variations of this approach can be used to model acute injury, acute injury followed by repair, and repeated cycles of DSS interspersed with recovery modeling chronic inflammatory diseases 2. After a single four-day treatment of 3% DSS in drinking water, mice show signs of acute colitis including weight loss, bloody stools, and diarrhea. Mice are euthanized at the conclusion of the treatment course and at necropsy dissected colons are processed and can be 'Swiss rolled" 3 to allow microscopic analysis of the entire colon or infused with formalin as "sausages" to allow macroscopic analysis. Tissue is then embedded in paraffin, sectioned, and stained for histologic review.

    Protocol

    Part 1: Injury-Repair Colitis Model

    1. Baseline weight should be obtained for each mouse prior to beginning DSS treatment.
    2. Make a 3% (w/v) Dextran Sulfate Sodium Salt solution in water and filter with a 0.45 μm cellulose acetate filter.
    3. Replace drinking water in the mouse cage with the 3% DSS solution for four days. The mice should not have access to any other source of water (i.e. exclusion tips placed on automated watering systems).
    4. On day four, replace the DSS solution with water for an additional three days, allowing some colonic epithelial recovery. The mice should be weighed on day four in order to quantify systemic consequences of colitis. Weight loss is common with severe injury.
    5. On day 7, weigh and sacrifice the mice. Mice can be euthanized by inhalational overdose of isoflurane, or other institutionally, IACUC approved methods.

    Part 2: Necropsy and Harvesting of Colon

    1. Expose the ventral side of the mouse and secure legs to ensure unobstructed access to the abdomen. Wet the abdomen completely with 70% ethanol.
    2. Grasp the midline of the abdomen with tissue forceps and extend upwards thus tenting the skin. Use fine-tipped scissors to incise the abdomen thus exposing the abdominal contents. Extend the incision to the tip of the xyphoid process at the midline and then extend along the inferior aspect of the costal margins bilaterally.
    3. Identify the small intestine, cecum, and colon. Carefully dissect/tease the colon from the surrounding mesentery. Transect the colon deep in the pelvis to free the distal colon and rectum. Transect the colon at the colonocecal margin to free the proximal colon. Care must be taken during this process not to damage the colon as cleaning the colon will be problematic if perforation occurs.
    4. Using a 20G feeding needle and 10 ml syringe, intubate and flush the colon with ice-cold PBS until the eluate is completely clear of stool.
    5. At this point, if macroscopic analysis with a dissecting microscope is desired, the colons can be fixed as “sausages”. If histologic analysis only is desired than proceed to Part 4 “Making Swiss Rolls for the Histological Analysis of Acute Colitis”.

    Part 3: Processing as “Sausages” for Macroscopic Analysis of the Entire Colon

    1. It is important to maintain the correct orientation of the colon, therefore, keep the distal end of the colon closest to the operator. Cut two pieces of non-absorbable suture (SP116 1.5 metric braided silk), one approximately 1 inch in length, the other 2 inches.
    2. Use the 2 inch piece of suture to tie off the distal end as close to the margin as possible while still maintaining a good seal.
    3. Place a 20G feeding needle containing 5 ml of 10% buffered formalin phosphate into the proximal end of the colon. Loosely tie the remaining piece of suture immediately proximal to the bulb of the feeding needle. Grasp the colon firmly at the bulb of the feeding needle and infuse formalin until the colon is expanded. Tighten the knot in the suture as you withdraw the feeding needle, thus leaving the infused, expanded colon as a “sausage”.
    4. Fill a 15 ml conical tube with 10% buffered formalin phosphate and place the colon in the tube. Fix for 24 hours.
    5. Pour off formalin and replace with 70% EtOH for an additional 24hrs. (Colons can be stored in 70% EtOH indefinitely at room temperature.)
    6. Remove the colon from the conical tube and cut the strings on each end with a scalpel, being careful not to damage the colon. Remember that the distal end has the longest piece of string. Cut longitudinally from the distal to proximal end of the colon so that it forms a long sheet. At this point, the colon can be viewed under a dissecting microscope.

    Part 4: Making Swiss Rolls for the Histological Analysis of Acute Colitis

    1. It is important to maintain the correct orientation of the colon, therefore, keep the distal end of the colon closest to the operator.
    2. Measure the colon length. This metric is another indicator of the severity of injury. Colitis increases edema and shortens the overall colon length.
    3. Using fine-tipped scissors, incise longitudinally from distal to proximal end of the colon. Use fine tipped forceps to grasp either edge of the incision and open laterally working your way distally->proximally, thus displaying the colon as a flat sheet.
    4. Rolling the colon requires a pair of forceps and a two handed technique. Grasp either edge of the distal margin with forceps. Proceed to sequentially roll the colon by rotating and releasing the forceps proceeding to the proximal margin. Thus generating a spiral with a third dimension or “Swiss Roll”. To maintain the rolled form, grasp the roll firmly with forceps and transect it with a 27G1/2 needle. Secure the needle by bending the needle as it exits the roll.
    5. Place the roll in an appropriately labeled tissue cassette and place in a jar of 10% buffered formalin phosphate at room temperature for 24 hrs to ensure tissue fixation.
    6. Pour off formalin and replace with 70% EtOH for an additional 24hrs. (Colons can be stored in 70% EtOH indefinitely at room temperature.)
    7. Once the sample has been fixed, it can be paraffin-embedded, sectioned and mounted on slides for histologic analysis.

    Part 5: Representative Results

    The DSS model for acute colitis allows the researcher to obtain, fix, and analyze a colon that models acute colitis. When the Swiss roll is cut and mounted, it should form a representative slice of the entire colon if rolled properly (Figure 1). The mounted roll can be stained with H&E in order to determine the extent of damage to the colon, from the distal (inside) end to the proximal (outside) end (Figure 2). Immunohistochemistry can also be performed on the Swiss roll to identify and quantify inflammatory infiltrates. If the sausage method has been performed correctly, the fixed colon will be dilated and the entire mucosal surface can be easily manipulated and viewed under the dissecting microscope (Figure 3).

    Figure 1
    Figure 1. The properly-executed "Swiss roll". (A) The colon is rolled from the distal to proximal end, transected with a needle and secured by bending the end of the needle. It is then placed in a tissue cassette for fixation. (B) H&E stained 5 μm section of a Swiss roll made from the colon of a mouse treated with DSS (d= distal colon p= proximal colon).

    Figure 2
    Figure 2. DSS treated colons show signs of acute colitis. Inflammation and crypt damage are apparent in the DSS-treated colon compared to a water treated control.

    Figure 3
    Figure 3. An example of a "sausage". The sausage infused with formalin and completely expanded. A slight angle will be present secondary to the natural curvature of the colon. The opened sausage should lie flat.

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    Discussion

    This protocol can be modified to model acute injury, injury-repair, or chronic colonic injury processes.

    Acute Injury Modification:

    DSS treatment ad lib for 4-6 days followed by immediate sacrifice

    Injury-Repair Modification:

    Injury with 4-6 days of DSS treatment followed by recovery period of 3-4 days and sacrifice (as described in above protocol).

    Chronic Colitis Modification:

    Mice are placed on three five-day cycles of 3% DSS with sixteen days of recovery between each cycle. Mice are sacrificed after the final 16-day rest period.

    There are several issues that researchers need to be aware of with this model:

    1. Variability in site of injury: In our hands, we see a predominantly distal injury pattern, with relative sparing of the proximal colon and cecum. Others have reported more proximal predominance to the injury pattern.
    2. Environmental variability. There is significant environmental variability. This is likely, in part, due to differences in intestinal microflora, diet and other environmental considerations.
    3. This model is ineffective if high molecular weight DSS is used (i.e. 500,000 Da).
    4. There is considerable strain variability with this model 4.

    Biochemical analysis of the colon can be performed by taking samples from the proximal or distal margins. Depending on the severity of injury this may impact your ability to generate a histologic injury score. In vivo BrdU labeling to measure proliferation can be achieved by intraperitoneal injection of 16.7 μg/kg BrdU 2 hrs prior to sacrifice followed by α-BrdU IHC processing.

    As an alternative to the “sausage”, the colon can be fixed completely flat. Line the bottom of a Tupperware container with Whatman paper and soak the paper with 10% buffered formalin phosphate. Dissect the colon as described in “Part 2: Necropsy and Harvesting of Colon”. Again, keep the distal end of the colon closest to the operator. Using fine-tipped scissors, incise longitudinally from distal to proximal end of the colon. With fine tipped forceps grasp either edge of the incision and open laterally working, thus displaying the colon as a flat sheet. Transfer this flat sheet to the pre-soaked Whatman paper. Cover the flattened colon with another piece of Whatman and wet with 10% buffered formalin phosphate. The Whatman should be completely covered in formalin but not so much that it lifts off the colon. Seal the Tupperware and fix for 24 hours. Remove the colon from the Tupperware and place it in 10 ml 70% ethanol in a 15 ml conical tube. (Colons can be stored in 70% EtOH indefinitely at room temperature.)

    There are several methods for quantifying colonic injury 5,6,7. One method, for example, uses a multi-parameter scale including: inflammation, extent involvement, regeneration, crypt damage, and percent involvement 8.

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    Disclosures

    Experiments on animals were performed in accordance with the guidelines and regulations set forth by Vanderbilt IACUC.

    Acknowledgements

    Funding provided by NIH (1 K08 DK080221-01) and Vanderbilt institutional development funds.

    Materials

    Name Company Catalog Number Comments
    Dextran Sulfate Sodium Salt USB Corp., Affymetrix 9011-18-1 mol wt 40,000-50,000
    10% Buffered Formalin Phosphate Fisher Scientific SF100-4
    Isoflurane, USP Phoenix Pharmaceuticals, Inc. NDC 57319-474-06
    TISSUE PATH Macrosette Cassettes Fisher Scientific 15182706
    BD 10 ml Syringe BD Biosciences 309604
    Ethyl Alcohol Pharmco-AAPER E190 Dilute to 70% with distilled water
    20G Straight Feeding Needle VWR international 20068-612
    27G1/2 PrecisionGlide Needle BD Biosciences 305109
    Dissecting Scissors Sharp/Blunt Tip VWR international 82027-588
    Waugh Forceps VWR international 82027-428
    Non-absorbable Suture LOOK Surgical SP116
    Whatman Blotting Paper VWR international 28298-020 Cut as needed
    Nalgene Surfactant-Free Cellulose Acetate (SFCA) Filter Cole-Parmer EW-06731-2
    Carbon fiber composites digital caliper Fisher Scientific 15-007-958

    References

    Comments

    50 Comments

    what kind of mice you used in the experiment? hao ole of the mice when you treatment with DSS
    Reply

    Posted by: echo r.March 18, 2010, 8:43 PM

    We use both 1²9 and C57BL6 mice in this experiment but the protocol can be used in any background. The mice are at least 6 weeks old before we begin treatment with DSS.
    Reply

    Posted by: Caitlyn W.March 19, 2010, 10:27 AM

    what kind of mice you used in the experiment? hao ole of the mice when you treatment with DSS
    Reply

    Posted by: echo r.March 18, 2010, 9:36 PM

    what happens if we keep the colon more than ²4 hours in 10%formalin ?
    Reply

    Posted by: peyman m.May 23, 2010, 6:17 AM

    Leaving them in the 10% formalin shouldn't be a problem. We have left them over the weekend. For counts, longer fixation shouldn't be problematic, but I would put them in 70% ethanol before the end of 3 days.
    Reply

    Posted by: Caitlyn W.May 23, 2010, 6:38 PM

    should DSS be prepared daily? and why it need be filtered?&#²9²59;Is the coulor of the solution&#²9²59;(DSS solute in filter water ) yellow
    Reply

    Posted by: AnonymousJune 15, 2010, 8:50 AM

    The DSS dŒs not need to be prepared daily. You can fill a water bottle enough for the four days on DSS. It needs to be filtered because you will be handling it before filtering and it can harbor bacteria, etc. that you don't want to feed to your mice. Yes, the color of the solution is slightly yellow.
    Reply

    Posted by: Caitlyn W.June 15, 2010, 11:52 AM

    should I store the solution in routine temperature or in the fridge?
    Reply

    Posted by: AnonymousJune 16, 2010, 2:50 AM

    It is stored at room temperature.
    Reply

    Posted by: Caitlyn W.June 16, 2010, 12:54 PM

    should I change the solution containing dss daily ? dŒs it influence the result if i do not change the solution daily?
    Reply

    Posted by: AnonymousJune 16, 2010, 9:48 PM

    There is no need to change the solution daily. Just put enough DSS solution in the water bottle on day one to last for the duration of the first cycle of DSS.
    Reply

    Posted by: AnonymousJune 17, 2010, 12:02 PM

    In our animal facility ,autoclaved tap water is used for all the mice. can I prepare DSS solution in tap water and then filter , or only distilled water shuld be used.
    Reply

    Posted by: AnonymousJune 17, 2010, 12:57 AM

    You can prepare the solution in tap water and then filter.
    Reply

    Posted by: AnonymousJune 17, 2010, 12:03 PM

    Dear Drs Whittem, Williams and Williams:

    Hello, I am writing a protocol to my University's IACUC to perform DSS induction of colitis, and was hoping that you may be willing to answer some of my questions regarding the animals subjected to DSS. I will be using the acute injury and injury repair models mentioned in your article. Could you please provide additional details of the stress that the mice might experience throughout the course of the experiment? The signs stated on the tutorial included weight loss, bloody stools, and diarrhea. Do these mice have additional issues such as an inability to retrieve food from an overhead feeding dish/water bottle, anorexia, inability to groom, contractures (i.e. 'hunching' in response to pain) or additional signs that may be useful to note when submitting my protocol? Also, should I expect mortality during treatment? As recommended, I will use mice older than six weeks, but likely not several weeks older as I want to avoid age-related issues. Finally, would you recommend the use of any type of analgesic drug during the course of DSS-colitis experiments to minimize discomfort in these animals? If so, would you happen to know the effect the analgesic has on factors such as barrier function, healing, infection rate, overall survival etc.? As I do not yet have any personal experience with this model, any insight will be greatly appreciated. Thank you.
    Reply

    Posted by: Elle F.June 28, 2010, 8:03 AM

    For the acute injury and injury repair models you should only see the stresses mentioned in the article, weight loss, bloody stool, and diarrhea. There are no additional issues and you should not expect mortality during treatment. I would not recommend the use of an analgesic drug because, for example, NSAIDs will injure the gut and they should not be needed. Good luck!
    Reply

    Posted by: Caitlyn W.June 28, 2010, 10:52 AM

    How do you utilize the sausages? I assume you slit them lengthwise after fixation and then stain (with what?) and examine them enface in a dissecting scope. What can you learn from this type of examination? Do you have a preferred method for quantitation of the resultand data?
    Reply

    Posted by: John W.July 30, 2010, 3:05 PM

    You are correct, the sausages are cut lengthwise and stained with methylene blue and analyzed for aberrant crypt foci and polyp burden. The data is collected as and quantified as numbers of ACF/colon or number or size of polyps per colon.
    Reply

    Posted by: Caitlyn W.July 30, 2010, 3:19 PM

    Read the abstract,
    "Mice are euthanized at the conclusion ... and at necropsy ... and can be 'Swiss rolled" 3 to allow microscopic analysis of the entire colon or infused with formalin as "sausages" to allow macroscopic analysis. Tissue is then embedded in paraffin, sectioned, and stained for histologic review."

    "Swiss roll" is for histological analysis, while "sausage" is for macroscopic analysis of the ENTIRE colon.
    Reply

    Posted by: AnonymousDecember 6, 2010, 11:21 AM

    is dextran a reliable model for colitis...?do i use the drug for treatment before or after colitis using dextran?
    Reply

    Posted by: AnonymousJune 12, 2011, 7:20 AM

    DSS is one of the better models for colitis. The papers found at the following sites as well as those that we cite in our paper give good information on the topic. http://www.ncbi.nlm.nih.gov/pubmed/9844047?dopt=Citation http://www.ncbi.nlm.nih.gov/pubmed/8881816?dopt=Citation http://www.ncbi.nlm.nih.gov/pubmed/14611673?dopt=Citation We have not performed treatments on mice on DSS. We mainly use it to analyze the response of knockout models to experimental colitis. Treatment times would depend on whether you would like to prevent or treat colitis.
    Reply

    Posted by: Caitlyn W.June 15, 2011, 6:24 PM

    I'm working with this model, but using ²% DSS as described. We bought our chemicals from another company, but the molecular weight is the same. Can you tell me more about the bloody diarrhea. I have finished the DSS water, but did not notice any blood. There was a bit of an excessive amount of feces, but I did not see the mice hair (white) or bedding stained with dried blood. I've read in other papers that not all the mice have it, but dŒs the fact that I did not see any mean that something went wrong?
    Reply

    Posted by: AnonymousJuly 17, 2011, 1:21 PM

    There can be considerable variability in the severity of colitis induced by DSS. This depends on manufacturer, lot #, environment, differences in enteric flora. We typically track weights, DAI which includes stool consistency, blood, etc, measure colon length and weight at necropsy and for us, we consider the histology observed from reviewing the H+E's as the gold standard for injury. I would recommend reviewing the histology with a GI pathologist.
    Reply

    Posted by: AnonymousJuly 20, 2011, 3:00 PM

    I am submitting a protocol for DSS to the IACUC. They want to know how I "will deal with the diarrhea with occult blood". Is there anything that we can administer to the mice to make the IACUC happy? They want to know how long I will let these symptoms go on before removing the mouse from the study. Unfortunately, all of these things are facets of the disease.
    Reply

    Posted by: AnonymousAugust 18, 2011, 10:09 AM

    Hello Jesse,
    We insure that IACUC knows that mice that drop below ²0% weight loss are sac'd. The amount of time that mice are on DSS results in diarrhea and blood for only 4-6 days and mice recover well. You should not have to worry about mice having symptoms for more than a week.
    Reply

    Posted by: Caitlyn W.August 18, 2011, 12:00 PM

    Thank you for your response. Another question...if the mice are in distress(eg. bloody diarrhea) but we don't give them any analgesic, then the IACUC will make them go down as Category E by USDA standards. DŒs anyone else have experience with this? DŒs anyone else list them as Category E?
    Reply

    Posted by: AnonymousAugust 18, 2011, 2:00 PM

    Ours are Category E
    Reply

    Posted by: Caitlyn W.August 18, 2011, 6:19 PM

    The water to be used with the DSS should be autoclaved water?
    Reply

    Posted by: Lilian N.August 18, 2011, 10:50 PM

    DŒs anybody do anything to combat dehydration in these mice?
    Reply

    Posted by: AnonymousAugust 19, 2011, 10:56 AM

    Sucrose 6%.
    http://farncombe.mcmaster.ca/documents/Ghiaetal.GastrŒnterology²0091367²²80-²²88.pdf
    Reply

    Posted by: Lilian N.August 19, 2011, 12:57 PM

    The water used with DSS dŒs not need to be autoclaved. You should filter it after making the DSS solution. We do IP saline injections.
    Reply

    Posted by: Caitlyn W.August 19, 2011, 1:39 PM

    DSS will be degrade or not in water. How DSS solution will be filtered what is procedure for that.can u elaborate thanks
    Reply

    Posted by: AnonymousSeptember 24, 2011, 3:11 AM

    We have not officially tested whether DSS degrades in water over extended periods of time. We make fresh DSS solutions for each cycle of DSS that is administered and do not reuse the DSS that is remaining in the water bottles after each cycle. As mentioned in the protocol, we make a 3% (w/v) Dextran Sulfate Sodium Salt solution in water and filter with a 0.45 μm cellulose acetate filter (Nalgene Surfactant-Free Cellulose Acetate (SFCA) Filter, Cole-Parmer, catalog number: EW-06731-²). The directions for this filter come with it but it is simply a vacuum filtration system as pictured in the video (seen at 0:5², "Injury-Repair Colitis Model").
    Reply

    Posted by: Caitlyn W.September 25, 2011, 3:50 PM

    Has anyone used buprenorphine in the DSS model?
    Reply

    Posted by: AnonymousSeptember 27, 2011, 1:29 PM

    Question: In this mouse model of DSS colitis, do we have to to remove the colon contents (stools) before histological analysis? How is this done? Thank you!
    Reply

    Posted by: AnonymousOctober 14, 2011, 10:49 AM

    At 3:17 in the video the removal of stools is shown. The colon is flushed with PBS using a ²0G straight feeding needle.
    Reply

    Posted by: Caitlyn W.October 17, 2011, 4:38 PM

    In some protocols, people sacrifice the mice 3 or 5 days after DSS treatment. What is the purpose of this? How is this different from killing the mice after 4 days of DSS treatment.
    Reply

    Posted by: AnonymousJanuary 16, 2012, 4:52 PM

    The number of days that you sac after DSS treatment will determine the amount of time the mice have to heal. we generally use 4 days because, in wild type mice, this is usually the best amount of time to see the beginnings of recovery while still noting damage in the mice of interest used in our lab. Basically, this is the point at which we see the most difference between the two groups. If you have a mouse that you expect to heal more quickly, 3 days may be suitable, and vice versa.
    Reply

    Posted by: Caitlyn W.January 18, 2012, 1:21 PM

    Regarding the step 7 of part 4 in the protocol mentioned above, how do you remove a needle from a swiss-rolled tissue before going forward to paraffin-embedding? Just pull out? Do you have a specific way to do that?
    Reply

    Posted by: AnonymousJanuary 17, 2012, 6:05 PM

    Once the tissue is formalin fixed, the tissue will be stiff enough that you can either unbend or clip the needle and slide it out of the roll without altering the shape of the Swiss roll. Our tissue processing core knows how to handle our tissue, but if you need to do it yourself, insure that the tissue has been in 70% ethanol at least overnight and then use gloves and forceps to remove the needle from the roll.
    Reply

    Posted by: Caitlyn W.January 18, 2012, 1:24 PM

    What are the strains of mice used for this model? And what is the health status of the animals?
    Reply

    Posted by: AnonymousFebruary 10, 2012, 11:16 AM

    We use C57Bl6 mice for our experiments. Our mice are healthy before treatment with DSS.
    Reply

    Posted by: Caitlyn W.December 13, 2012, 1:04 PM

    Hello, I am writing a protocol to my University's IACUC to perform DSS induction of colitis.Should I put DSS in Hazardous material form?Is there any method to detect the DSS excretion in feces and urine?How can we deal with the waste from DSS (unused solution)?

    Thanks,

    Reply

    Posted by: Jinggang L.December 13, 2012, 11:22 AM

    Our IACUC protocol dŒs not include DSS as a hazardous material and we pour waste DSS down the drain. As far as I know, there is not a method to detect DSS excretion in feces and urine.
    Reply

    Posted by: Caitlyn W.December 13, 2012, 1:06 PM

    Hi
    In the materials you list Dextran Sulfate Sodium Salt USB Corp., Affymetrix 9011-18-1 mol wt 40,000-50,000.
    However when I check Affymetrix website, this catalog number belongs to a MW: 500,000 product (http://www.affymetrix.com/esearch/search.jsp?pd=131111&N=4²94967²93) . is this what you used or otherwise what is the correct catalog number. thanks!
    Reply

    Posted by: selcen o.May 6, 2013, 10:50 AM

    I am so sorry for the confusion. The number listed in the protocol is the CAS# which is similar between the 500,000 and 50,000 M.W. DSS. The actual catalog number is 14489. This number should get you what you need (http://www.affymetrix.com/estore/browse/brand/usb/product.jsp?productId=130²61#1_1).
    Reply

    Posted by: Caitlyn W.May 6, 2013, 12:00 PM

    Thanks a lot for the catalog number!
    Could you please explain the injection of saline to prevent dehydration? How often and how much should it be injected? I guess all mice should get the same amount at the same time, right?
    And when the mice get sick, should we put some food on the bottom of the cage, or are they usually capable of getting the food themselves? thanks again.
    Reply

    Posted by: selcen o.May 13, 2013, 3:44 PM

    We usually only inject mice that are not looking healthy and we generally do this as needed. I will only inject a 1ml bolus on a single day. You can repeat this the next day, but this is really just a last resort. We sacrifice them once they reach ²0% weight loss so they don't have undue stress. When the mice get sick, I do tend to try and put food in the bottom of the cage in case the mice aren't able to reach up into the food distributor. If the mice are getting so sick that you need to inject with PBS or move the food down, you may want to try a smaller concentration of DSS (²% or 1%) or perform the treatment for a shorter time. We have had several genotypes that don't handle the DSS as well and decreasing the concentration or treatment time really helps them. There is also facility to facility variability dependent on mouse microbiomes so my mice may be less sensitive than your mice to DSS and even your WTs might have different responses than mine. In short, we often need to tweak the protocol so that we can get injury while insuring survival for the extent of the protocol that we need to perform.
    Reply

    Posted by: Caitlyn W.May 13, 2013, 4:29 PM

    thanks a lot, Caityln, you are really helping a lot because we have no experience in that.
    Reply

    Posted by: selcen o.May 14, 2013, 4:56 AM

    Inducing colorectal cancer in rats: I am in a predicament; instead of the DSS Mw 40,000, I have ordered DSS (Mr 5,000) by accident. Unfortunately I noticed this too late and have a very limited time. I have read that the Mw of DSS does play a role in inducing colitis, whereby 5 kDa could induce milder form of colitis. I plan to inject my rats with AOM (12 mg/Kg), expose the rats to 2 cycles of 1 week of 2% DSS following 2 weeks of water. These rats are quite old, 12 weeks to be exact. They are also Wistar rats so at this time they are prone to develop cancer easily. However, I would like to know is using 5 kDa DSS worth it? Could you please provide me with some advice?
    Reply

    Posted by: Lynn C.February 16, 2014, 6:30 AM

    Unfortunately, I do not think that Mr 5,000 will work.
    Reply

    Posted by: Christopher W.February 19, 2014, 9:21 AM

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