TIME-COURSE OF NEUROPEPTIDE CHANGES IN PERI-ISCHEMIC ZONE AND AMYGDALA FOLLOWING FOCAL ISCHEMIA IN RATS

Previously, using a middle cerebral artery occlusion model in Wistar r at, we showed autonomic disturbances similar to those seen clinically and observed striking neurochemical changes in cortical and subcortica l sites at 5 days following stroke. The neurochemical changes may acco unt for functional recovery and/or autonomic disturbances after focal ischemia. To understand the possible mechanisms and to facilitate futu re studies, it is necessary to define the time-courses of these change s. Using immunohistochemical staining with the peroxidase-antiperoxida se reaction, the changes in several neuropeptides over the peri-ischem ic region and the ipsilateral central and basolateral nucleus of the a mygdala were investigated at different times after middle cerebral art ery occlusion. In the experimental group, neuropeptide Y immunoreactiv ity appeared to increase by 6 hours in the peri-ischemic region. Using image analysis to quantify the staining intensity, the change became statistically significant at 1 day, peaked around 3 days, and subsided at 10 days. There was a delayed increase in neuropeptide Y in the ips ilateral basolateral nucleus of the amygdala with a peak around 3 days . Immunoreactive staining for leucine-enkephalin, dynorphin, and neuro tensin demonstrated an increase that was localized to the ipsilateral central nucleus of the amygdala with a peak around 3 days and a return to baseline levels by 10 days. The results support a specific time-co urse for each of the neuropeptides studied and indicate that a surviva l time of 3 days after focal ischemia is the critical period for exami ning the relationship between neuropeptide responses and neuronal or f unctional recovery. (C) 1995 Wiley-Liss, Inc.