Dear Sir/Madam,
My name is John and i been doing animal models for quite some time. Recently taken up Animal models in diabetic condition as the main topic. I had fixed several doses for inducing diabetes by STZ,50,55 and 60mg/kg.b.wt.As usual the animals were fasted overnight and STZ was prepared freshly along with normal saline. The chemical was than administered as ip .Blood glucose levels were raised up to 500mg/dl in 55 and 60mg/kg.b.wt but at 50mg/kg.b.wt the initial blood glucose levels were up to 150-200mg/dl,after the 7th day the blood glucose levels have come down to 65 and 70mg/dl.Iam confused.
I would request your good self to kindly help me in this regard and do the needful

jwilkineinstein,

Welcome to the fun world of making animals diabetic. Streptozotocin dosing in rats is typically done by two methods. At 55 and 65 you are in the "high" dose range. At this level you rapidly induce the killing of beta islets and you get very high glucose levels rapidly. The rats probably succomb soon after reaching 500mg/dl? At 50 mg/kg you are in the "low dose" range of this drug. You get an initial glucose rise response, then the animals can recover. this may be due to islet expansion and making more insulin which halts the drugs killing of beta cells though there is some argument about this. In mice we typically dose the animals on 5 consecutive days with 50mg/kg. Then we wait 4 weeks for an effect on blood glucose, after 8 weeks the glucose will reach 500 mg/dl as the beta cells are killed by immune mediated attack. You can get more info on this at the AMDCC.

http://www.amdcc.org/

Rb

Dear Sir,
Thanks a lot for your advice.I would like to bring to your kind attention that iam not a ADCC member,but i would be happy if iam one among the members and will do the needeful to the group.How do i go about?

Do you have any information in regard to Effect of STZ on rats.
Kindly help.
Thanking you sir,
Warm regards,
Wilkin

jwilkineinstein -

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Dear John

Let me tell you the basic mechanism of action of SZT. As we all know it is a cytotoxic chemical which has direct effect on the beta cell. After the STZ injection it starts to destroy the beta cell and hence the insulin level will be effected therefore to neutralize that effect the secretion of insulin from remaining beta cell will be higher. That is why at one week you got the low level of glucose because the animals you are using might have more resistance then normal animals. So be cool and calm and wait for another one week, you will definitely get the hyperglycemic model. If you required then you can inject another dose of STZ at 2nd week after checking the glucose level.

As Rb has already asked you, if you have used normal saline then use 0.01 M citrate buffer. I think this will solve your problem. If not then let us know we will try to resolve it by discussing.

People are using STZ model mainly for Type I diabetes only

Chintan