Establishment And Evaluation Of Experimental Bama Miniature Pig Model With Type 1 Diabetes Mellitus

Objective: To discuss the metabolic characteristics and pancreatic pathology and histology changes of Bama miniature pig model with type 1 diabetes mellitus(T1DM)established by the intraperitoneal fraction injection of streptozotocin(STZ),which could provide a suitable animal model for the more widely research of diabetes mellitus.Methods:(1)A total of 20 healthy male Bama miniature pigs,fed a normal diet,were randomly distributed into the small-dose model group,medium-dose model group,large-dose model group and normal control group.The model groups,fasted overnight,received intraperitoneal injections of STZ at 50 mg/kg,75 mg/kg and 100 mg/kg,respectively,and one additional double injection of STZ(100 mg/kg,150 mg/kg and 200 mg/kg)after the stabilization for one week.The general conditions and body weight changes of miniature pigs were observed.The fasting glucose was measured every other day before and after the modeling,and the pancreatic tissue was stained with hematoxylin and eosin(HE)at the end of the experiment.(2)The selected male Bama miniature pigs(n=12)were randomly distributed into the model group(n=6)and the control group(n=6),the model group accepted the intraperitoneal fraction injections of STZ(75 mg/kg,150 mg/kg)to establish the animal model.The alanine aminotransferase(ALT),aspartate aminotransferase(AST),creatinine(Cr)and blood urea nitrogen(BUN)concentrations were measured before and after the modeling.One week after the modeling,all miniature pigs were conducted with the oral glucose tolerance test(OGTT)and insulin releasing test(IRT).The pancreatic tissues were conducted with HE staining,insulin immunohistochemical staining and islet beta cell apoptosis measuring by TUNEL method.Results:(1)The modeling for the miniature pigs in medium-dose model group was successful,without any death and infection,the modeling miniature pigs had three increased and one decreasing symptoms.(2)After injections of STZ for 13 days,the fasting blood glucose of the miniature pigs in the model group was obviously increased and steadily maintained the level at 7.6-17.1mmol/L.(3)The blood glucose levels of 5 time points of OGTT in the model group were obviously higher than those in the control group(P < 0.01),while the insulin levels of 5 time point of IRT were markedly lower(P < 0.01),and the insulin continuous was continuously low without any continuous peak.(4)Before and after the modeling,the ALT,AST,Cr and BUN concentrations of the model group had no obviously difference when compared with the control group(P > 0.05).(5)The HE staining of pancreatic tissues in the model group showed that the pancreatic islets were atrophied and the numbers of cells in the pancreatic islets were reduced.(6)The insulin immunohistochemical staining showed that the mean optical density of insulin staining in the model group [(15.96±2.16)%] was markedly lower than that in the control group [(55.47±5.35)%](P < 0.01).(7)The apoptosis rate of islet beta cell in the model group [(33.58±5.67)%] was markedly higher than that in the control group [(10.17±1.23)%](P < 0.01).Conclusions: The intraperitoneal fraction injections of STZ(75mg/kg,150mg/kg)could successfully establish a Bama miniature pig model with T1 DM,which was an ideal modeling method of T1 DM in miniature pigs,and could provide a good tool for human diabetes study.The modeling miniature pigs had characteristic manifestations and pathological changes of T1DM.