RITANSERIN, A 5-HT2 RECEPTOR ANTAGONIST, INCREASES SUBCORTICAL BLOOD-FLOW FOLLOWING PHOTOTHROMBOTIC MIDDLE CEREBRAL-ARTERY OCCLUSION IN RATS

It has been proposed that the reversal oi serotonin-mediated vasoconst riction accounts for the neuroprotective effect oi serotonin (5-HT2) r eceptor blockade in local cerebral ischemia. We investigated the effec t of pretreatment with ritanserin, a 5-HT2 receptor antagonist, on cer ebral blood flow in a model of photothrombotic middle cerebral artery occlusion in rats. Local cerebral blood flow was measured by iodoantip yrine autoradiography 30 minutes after induction of ischemia. Using a novel image-alignment algorithm, 3-dimensional reconstructions of aver aged cerebral blood flow were calculated. The difference-image of loca l cerebral blood flow between ritanserin and vehicle-treated animals r evealed a subcortical zone underlying the ischemic cortex where cerebr al blood now was markedly enhanced indicating a beneficial hemodynamic effect of ritanserin. Three-dimensional image analysis provides a pow erful tool to detect inter-group differences of cerebral blood flow wh ich are underestimated by conventional types oi data analysis.