Using this ip dose we find Their body weights normally decrease to 10% weight loss over 2 days and stabilise over 4 weeks , but their food and water intake increase dramatically. We provide softened food so it is easy for them and switch them to 22% protein diet at injection.

I never use any special diet- just the ordinary food pellet.

Your findings are correct. We have not found edema. Rats will definitely loose weight. Its type 1 diabetes. Normal food is ok if your interest does not involve diet manipulations.

Dear Sanket and Lisa, I have a few questions:

Lisa:

1. You say the weight stabilizes. Does this mean they do not gain weight anymore?

2. How old are your rats at time of injection? You don't expect some growth in my 8 weeks old rats (female)?

3. What glucose levels do you find over time?

4. Do you take any precautions to avoid too high glucose? Or maybe when you find high glucose give them an insulin implant?

Sanket:

1. What dose did you use?

2. What glucose levels do you find over time?

3. Do you take any precautions to avoid too high glucose? Or maybe when you find high glucose give them an insulin implant?

4. To clarify your first two sentences: you find everything the same except for the edema?

Does anyone have an idea what could cause the edema in my rats?

Many thanks!

1. Yes. Stabalise at approx 10% bwt loss

2. Male Charles River Wistar, 350-450g at time of dosing. We have found if inject

We have used single treatment of STZ, i.p., 60 mg/kg/mL in 10 mM citrate buffer, pH 4.5. In 24 hours I expect glucose level more than 300 mg/dL (~70% SD rats) and after week you will surely get 100% success, ~450-600 mg/dL. Many times, researchers have used nicotinamide pretreatment, 125 mg/kg/mL, i.p., to control hyperglycemia.

Dear Maarten

I have used both type of rats model. In the model of type 1 diabetes, I used 45 mg/kg of STZ I.P. in an adult wistar furth rat. At the beginning the rats look like normal, but I had to give them more water and more standar food. After 12 weeks of diabetes the diabetics rats loosed weigth in comparision with control. The diet were no necesary to get the glycemia level needed to perform the model.

In the other hand I performed research in a type 2 diabetes rat model (female sprague D). I inyected them 45mg / kg of STZ I.P. at the age of 2 days. Only at the first 2 days after the inyection they have an increase glycemia level. From the day 5 up to they started eating high-fat-diet (8 weeks after) the glycemia were normal. Not only they look like normal but also they had never increased the weigth.

I've attached both the paper of type 1 DBT and the Type 2 DBT. And you could find it in my profile.

The other work.

STZ can be tricky to work with. I have occasionally had a rat remain normoglycemic after three doses of STZ at concentrations that would normally induce diabetes after one injection. I have also occasionally had a rat stop eating and require euthanasia.

I have never experienced edema in my STZ treated rodents, is it that all of the rodents have edema? Have any been sacrificed so that you can take a look? What is the STZ dissolved in? Are the rates showing any signs of distress? porphyrin staining, rough coat, hunched posture?

Remember that STZ is a blunt tool, it can cause all kinds of damage. Edema can be caused by kidney or liver damage, so if you cannot sacrifice a rat early to take a look, make sure to do a thorough necropsy when you do sacrifice the rats, or take some tissues for histology.

When STZ works, you can expect your rodent to lose weight, especially if you use a high dose protocol and do not treat them with insulin. The easiest way to treat with insulin is by implanting insulin pellets from Lin-Shin after the BG has stabilized. You can implant whole pellets or cut the pellets and give smaller doses of insulin and in this way titrate the BG that you wish to maintain. Pellets last about 30 days and then would need to be replaced.

Be careful with juvenile rats that do not gain weight. In my research, I extend the institutional policy of sacrificing any animal that loses 20% or more of body weight by comparing expected weight for a particular rat at a given age and ensure that my rats are at least keeping up within 20% of expected weight for age, sex and strain. Otherwise I suspect one may be studying starvation as opposed to diabetes.

Your rats may be hypertensive. What about to measure tension from tails?

The reason of belly blown up may be pseudopregnancy. If you put a female with old male in a cage you can see this phenomenon

For the edema you observe, we see that the gi-tract is extended with gas and the rats seem to have an increased gut transit time, with slightly loose stool. They spend the majority of their time eating and sleeping.. Their gut microbiome is likely to be altered an coupled with an increased drive to eat, I think this explains your observations.