Insulin induces tyrosine phosphorylation of a 90-kDa protein during postischemic brain reperfusion.

Rat brain nuclear proteins were examined for tyrosine phosphorylation after resuscitation from a 10-min cardiac arrest. Insulin (1 unit/kg intravenously), given immediately after resuscitation, caused a marked increase in tyrosine phosphorylation of a 90-kDa brain protein. This effect occurred without hypoglycemia and was not observed after insulin administration in previously insulinopenic, diabetic, nonischemic animals. Insulin-responsive tyrosine phosphorylation of a specific 90-kDa protein during reperfusion may represent insulin stimulation of a neuroprotective brain response to an ischemic insult, consistent with recent observations that insulin administration during reperfusion protects selectively vulnerable neurons from postischemic death.