Levemopamil reduces spatial learning deficit following transient occlusion of common carotid arteries in normotensive rats.

The effect of the calcium channel blocker and 5-HT2 antagonist levemopamil on spatial learning impairment of rats subjected to transient bilateral clamping of carotid arteries (BCCA) was investigated. In addition, the acute effect of BCCA on local cerebral blood flow was measured in the presence and absence of levemopamil in a separate group of rats. Pretreatment with levemopamil prevented the BCCA-induced increase in escape latency during the test trials and ameliorated the BCCA-induced decrease in spatial bias during a probe trial. Under these experimental conditions, local cerebral blood flow fell to near ischaemic values in all mid- and forebrain regions during occlusion of the carotid arteries. However, pretreatment with levemopamil affected the BCCA-induced blood flow changes only in one brain area of 34 investigated. The present data suggest that pretreatment with levemopamil reduces impairment in spatial behaviour and that this effect seems not related to the compound's cerebral vasodilatory action, but to direct neuronal mechanisms.