Background and purpose: Excitatory amino acids and their receptors are involved in mediating ischemic neuronal damage. The sigma-agonists are believed to interact with the N-methyl-D-aspartate receptor. Therefore, we studied the neuroprotective, hypothermic, and motor deficit effects of the sigma-agonist SKF 10,047 and the N-methyl-D-aspartate antagonist MK-801.
Methods: Neuroprotective effects were compared using an in vitro ischemia model of cultured rat cerebellar granule cells and the gerbil model of global brain ischemia induced by 5 minutes of bilateral carotid artery occlusion followed by 7 days of reperfusion.
Results: In vitro, (+)MK-801 protected against 100 microM glutamate with a 50% protective concentration of 30 nM, followed by (-)MK-801 (150 nM), cyclazocine (0.5 microM), (+)SKF 10,047 (3.3 microM), pentazocine (5 microM), and (-)SKF 10,047 (10 microM). In vivo, (+)SKF 10,047 pretreatment (60 mg/kg) or multiple postischemic treatments provided neuroprotection comparable with MK-801 pretreatment (10 mg/kg). When ischemic animals were administered the multiple dosing regimen of (+)SKF 10,047, no hypothermic effect was noted in the temporalis muscle over 4 hours' postischemia. Motor deficits monitored by a swing grid test showed that 50% recovery from (+)SKF 10,047 was 5.5 times faster than recovery from MK-801.
Conclusions: These results are the first to report a hypothermia-free, in vivo neuroprotective effect of (+)SKF 10,047, a prototypical drug of the sigma-agonist class.