Neuroprotection by the alpha2-adrenoceptor agonist, dexmedetomidine, in rat focal cerebral ischemia.

The present study was undertaken to explore the possible neuroprotective effect of the selective alpha2-adrenoceptor agonist, dexmedetomidine in a rat model of focal cerebral ischemia. The effect of dexmedetomidine (9 microg kg(-1)) on infarct volume was assessed and compared to that of glutamate receptor antagonists cis-4(phosphonomethyl)-2-piperidine carboxylic acid (CGS-19755) (20 mg kg(-1)) or 2,3-dihydro-6-nitro-7-sulfamoyl-benzo(F)quinoxaline (NBQX) (50 mg kg(-1)). Dexmedetomidine decreased total ischemic volume by 40% in the cortex (P<0.05) compared to NaCl-treated control rats, whereas NBQX reduced the infarct by 73% in the cortex (P<0.001) and by 43% in the striatum (P<0.01). Dexmedetomidine infusion was associated with some minor degree of hyperglycemia and hypotension. Drug-induced kidney changes were only seen in NBQX-treated rats. These results suggest that dexmedetomidine reduced ischemic volume despite causing a minor increase in blood glucose concentrations and hypotension. Its neuroprotective efficacy was better than that produced by CGS-19775, and dexmedetomidine was safer with respect to kidney toxicity when compared to NBQX.