Adenylate cylase activity and motor behavior following cerebral ischemia in the unanesthetized gerbil

Abstract

Five minutes of bilateral carotid occlusion in unanesthetized gerbils produced substantial changes in spontaneous locomotor activity. Behavior was decreased after 1 hr of reperfusion and was increased at 24 hrs post-ischemia. Adenylate cyclase activity was measured in homegenates of frontal cortex and hippocampus at 90 min and 24 hrs following 5 min of cerebral ischemia. Enzyme activity was determined in the absence and presence of the activators guanosine-5'-triphosphate (GTP), guanyly-5'-imidodiphosphate (GppNHp), isoproterenol (Iso) plus GTP, and forskolin (Fors) plus GTP. Homogenates responded with expected increases over basal adenylate cyclase activity with addition of all activators. An additional small increase in isoproterenol-stimulated activity was observed in frontal cortex homogenates at 90 min post-ischemia. No other significant changes in adenylate cyclase activity were observed after either 90 min or 24 hrs of reperfusion. The substantial increases in locomotor activity evident at 24 hrs after transient ischemia are not associated with measurable changes in adenylate cyclase activity in homogenates of frontal cortex or hippocampus.