The effects of insulin on the expression of caspase-3 and the neuronal apoptosis in rats after cerebral ischemia-reperfusion

Objective To investigate the effects of insulin on the expression of caspase-3 and the neuronal apoptosis in rats after cerebral ischemia-reperfusion.Methods 66 male Sprague-Dawley rats were randomly divided into 3 groups: sham operation group (sham), cerebral ischemia group (CI) and insulin intervention group (IN). The focal cerebral ischemia models of rats were established by the left middle cerebral artery occlusion (MCAO) with Longa's methods. Insulin and glucose was injected into the rat enterocoelia immediately post-occlusion in rats of insulin intervention group. Reperfusion began 2h after the left middle cerebral artery occlusion. At the prescriptive time, the rats were killed and decapitated to gain brains. Immunohistochemistry method was used to detect the expression of caspase-3 and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) was used to calculating TUNEL positive neuron.Results Compared with the sham operation group, the expression of caspase-3 increased obviously in cerebral ischemia group(P0.01). The expression of caspase-3 in insulin intervention group were decreased compared with the cerebral ischemia group(P0.01) and it ascended significantly compared with the sham operation,(P0.01). Compared with the sham operation group, the TUNEL positive neurons increased obviously in cerebral ischemia group(P0.01). The TUNEL positive neurons in insulin intervention group were decreased compared with the cerebral ischemia group(P0.01)and it ascended significantly compared with the sham operation(P0.01).Conclusions The transient cerebral ischemia-reperfusion ascended the expression of caspase-3 and promoted the neuronal apoptosis, but insulin descended the expression of caspase-3 and protected the neurons after the transient cerebral ischemia reperfusion.