Insulin Replacement Therapy Can Rectify The Impairments In Learning And Memory As Well As The Abnormalities In Apoptosis And In Bax Or Bcl-2 Protein Expression In The Hippocampal Subfields(CA1～CA3) Of Rat With Type 1 Diabetic Encephalopathy

Objective To investigate the effects of insulin administration on the Impairments in Learning and Memory as well as on the Abnormalities in Apoptosis and in Bax or Bcl-2 Protein Expression in the Hippocampal Subfields(CA1~CA3) of Rat with Type 1 Diabetic Encephalopathy. Methods Model of type 1 diabetic encephalopathy rats was made by intraperitoneal injection of a dosage of streptozotocin. After 5 days of successful establishment of the model, insulin was subcutaneously injected into each encephalopathy model rat. Morris water maze, terminal-deoxynucleotidyl-transferase-mediated-dUTP nick and labeling(TUNEL) technique, Bax and Bcl-2 immunohistochemistry were used to investigate the behaviors and cell apoptosis in the hippocampal subfields(CA1~CA3) of each rat. Results The abilities in learning and memory of type 1 diabetic encephalophathy rats were significantly weaker than those in the control group rats (p<0.01). Moreover, the numbers of Bax immunoreactive (Bax-IR) cells and TUNEL-positive cells in CA1,CA2, and CA3 subfields of hippocampus in encephalopathy group rats were significantly larger than those in control group rats (p<0.01); while the number of Bcl-2 IR cells of encephalopathy group rats was significantly smaller than that of control group rats (p<0.01). However, after 45 days of insulin treatment, the above parameters showed by encephalopathy group rats were reversed to the normal levels (p<0.01). Conclusion Insulin may reverse too much cell apoptosis by combining with insulin receptor to correct the abnormal expression of Bax or Bcl-2 gene in hippocampal subfields of rat with type 1 diabetic encephalopathy. The above data indicate that insulin is an important drug for early preventing and treating this diabetic complication...