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Abstract

Some studies have been performed on the effects of exogenous and endogenous opioids on cerebral blood flow. We investigated the effects of morphine on Cerebral Blood Flow (CBF) under normal, ischemic and reperfusion states and its neuroprotective effects after induced cerebral ischemia. Twenty male rabbits were divided in to two groups. At first CBF was measured in anesthetized rabbits as the baseline, then morphine (2 mg kg-1) and normal saline were administered intravenously to the case and control groups, respectively. The CBF was measured again at 10, 25 and 40 min after injection. Ten minutes after injection of drugs, both common carotid vessels were occluded with microvascular clips and they were opened 25 min after injection (or 15 min after occlusion of vessels). Hippocampal subfield CA1 was studied for pathological findings of ischemia. Morphine decreased the mean CBF values at pre-ischemic stage without any changes in mean arterial blood pressure (MAP) but this reduction was not significant as compared to control group. In reperfusion stage, CBF values of both normal saline and morphine treated groups, were lower than baseline significantly (p<0.05), but this reduction was not significant between two groups. In assessment of neuroprotective effect and neuronal cell damage, there was not any significant difference between the two groups. Our results are in contrast with other studies which suggest morphine to have increasing or decreasing effect on CBF. This variation in results may be due to dosage and route of administration or site and method of CBF Measurement.