Neuroprotective Effects of Local Surface Hypothermia during Endothelin-1-Induced Focal Ischemia in Rat Cerebral Cortex. II. Morphometric Analysis of Ischemic Lesions

In the present study, we investigated the neuroprotectiveeffects of local therapeutic hypothermia (LTH) in a model of focalischemia induced by epipial application of Endothelin-1 to the somatosensory cortexof the rat brain by morphometric analysis of ischemic foci formed3 hours after Endothelin-1 application. The size of ischemic fociwas measured in serial coronal brain slices after staining with2,3,5-triphenyltetrazolium chloride (TTC). It was found that coolingthe cortical surface to 28°C using a subdural Peltier element at0, 10 and 60 minutes delay after Endothelin-1 application, causeda significant reduction in the size of ischemic focus compared tonormothermic conditions. The neuroprotective effects of LTH wereinversely correlated with the delay of LTH onset from the time of Endothelin-1application and were most pronounced with LTH initiated with theshortest (0 and 10 minutes) delay after Endothelin-1 application.The size of the ischemic focus was also found to correlate significantlywith the degree of electrical activity suppression analyzed in parallelpaper. Taken together, the results of morphological and electrophysiologicalanalysis indicate pronounced neuroprotective effects of surfaceLTH, particularly significant at minimal LTH latency after ischemic onset,in a model of Endothelin-1-induced focal ischemia in the rat cerebralcortex.