| Objective To examine the effects of insulin replacement therapy on the learning and memory impairments as well as on cell apoptosis and on Bax or Bcl-2 protein expression in the nucleus basalis of Meynert and dianogal band of Broca of rat with type 1 diabetic encephalopathy.Methods Adult Wistar male rat model of type 1 diabetic encephalopathy was made by intraperitoneal injection of a dosage of streptozotocin(55mg/kg, body weight). After 5 days of successful establishment of the model, insulin(3 IU) was subcutaneously injected into each rat with the encephalopathy. Morris water maze, terminal-deoxynucleotidy-ransferase-mediated-dUTP nick and labeling (TUNEL) technique, Bax or Bcl-2 immunohistochemistry were used to separately investigate the behaviors and cell apoptosis in the nucleus basalis of Meynert and dianogal band of Broca of each rat.Results The abilities for learning and memory of rats with type 1 diabetic encephalophathy 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 nucleus basalis of Meynert and dianogal band of Broca 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 confront too much cell apoptosis by combining with insulin receptor to revert the abnormal expression of Bax gene or Bcl-2 gene in nucleus basalis of Meynert and dianogal band of Broca of rat with type 1 diabetic encephalopathy. The above data indicate that insulin is an important hormone for early preventing and treating this common diabetic complication.
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