Single dose streptozotocin-induced diabetes: considerations for study design in islet transplantation models

Abstract

Streptozotocin (STZ)-induced diabetes mellitus (DM) offers a very cost-effective and expeditious technique that can be used in most strains of rodents, opening the field of DM research to an array of genotypic and phenotypic options that would otherwise be inaccessible. Despite widespread use of STZ in small animal models, the data available concerning drug preparation, dosing and administration, time to onset and severity of DM, and any resulting moribundity and mortality are often limited and inconsistent. Because of this, investigators inexperienced with STZ-induced diabetes may find it difficult to precisely design new studies with this potentially toxic chemical and account for the severity of DM it is capable of inducing. Until a better option becomes available, attempts need to be made to address shortcomings with current STZ-induced DM models. In this paper we review the literature and provide data from our pancreatic islet transplantation experiments using single high-dose STZ-induced DM in NCr athymic nude mice with hopes of providing clarification for study design, suggesting refinements to the process, and developing a more humane process of chemical diabetes induction.

Figure 1

Mean blood glucose measurements of mice receiving STZ with standard deviation. Day 0 measurements were taken immediately before STZ injection. Blood glucose was not measured in every animal on every day. The number of animals for which blood glucose was measured each day is displayed at the base of each bar.

Figure 2

Peak blood glucose recorded from each animal after STZ injection but prior to islet transplantation (N=160). Peak blood glucose exceeded 400 mg/dl in 92.5% of animals.

Figure 3

H&E and insulin staining of pancreases 2 days after animals that received either an injection of HBSS (A, C) or HBSS with STZ (B, D). Panels A and C show healthy islets with normal morphology and substantial dark brown insulin staining. Panels B and D show damaged islets with abnormal morphology and minimal dark brown insulin staining.