Postischemic brain injury is affected stereospecifically by pentazocine in rats

We tested whether rats treated with the sigma1-receptor ligand, (+)-pentazocine, during transient focal ischemia would have a smaller volume of postischemic brain infarction than rats treated with the nonspecific opioid-receptor ligand (-)-pentazocine. Rats underwent focal cerebral ischemia using the filament occlusion technique for 2 h, followed by 22 h of reperfusion. Rats received (+) or (-)-pentazocine (n = 9 each group) at a dose of 2 mg x kg(-1) x h(-1) by continuous intravenous infusion from 1 h of ischemia to 22 h of reperfusion. Triphenyltetrazolium-determined infarction volume of ipsilateral striatum ([+]-pentazocine, 19 +/- 4 mm3, mean +/- SEM; [-]-pentazocine, 44 +/- 5 mm3) and cerebral cortex ([+]-pentazocine, 26 +/- 12 mm3; [-]-pentazocine, 134 +/- 29 mm3) was smaller in rats treated with (+) compared with (-)-pentazocine. Infarction volume in rats treated with (-)-pentazocine was also very similar to the infarction volume in saline-treated control rats from our previous study (striatum 44 +/- 4 mm3; hemisphere 136 +/- 27 mm3). These data indicate that sigma1-receptors may play an important role in the mechanism of injury both in cortex and striatum after 2 h of transient focal ischemia in rat.