Influence of growth hormone receptor gene knockout in pancreatic β cells in STZ-induced type 1 diabetes in mice

Objective: To investigate the influence of tissue-specific growth hormone receptor (GHR) deficiency in type 1 diabetes in the mice at the gene level using pancreatic β cells combined with streptozotocin (STZ) -induced type 1 diabetes model. Methods: The experiment was divided into four groups: knockout mice group (LLc knockout group), using the homozygotes (LLc: LL + Cre) producted by pancreatic (3 cell-specific expressed recombinant enzyme mice (RIP-Cre) and Cre-LoxP system modified GHR mice (Floxed, LL); LL control group, containing Floxed GHR allele homozygous mice (LL); LLc STZ group and LL STZ group (STZ was used for inducing type 1 diabetes model mice). The mice with feeding glucose ≥ 25 mmol·L^-1 were considered to be successful models. The Glucose Tolerance Test (GTT), pancreas tissue HE staining and immunohistochemistry were performed in the mice. Results: The blood glucose of the mice in LL STZ group and LLc STZ group and LLc STZ group were increased after injection of STZ and the models achieved the diagnostic criteria for diabetes 16 d later. The results of GTT showed that compared with LLc control group and LLc knockout group, the blood glucose levels of the mice in LL STZ and LLc STZ groups were increased (P<0.05). There was no significant change of morphology and structure of islets between LL control group and LLc knockout group detected by HE staining. The immunohistochemistry results showed that the insulin level of the mice in LL STZ group was significantly reduced compared with LL control group; the insulin level of the mice in LLc STZ group was reduced compared with LLc control group. Conclusion: Pancreatic β cell GHR gene knockout has no effect on the blood glucose and the function of β cells in the mice with STZ-induced type 1 diabetes.