Ionic channels, cholinergic mechanisms, and recovery of sensorimotor function after neocortical infarcts in rats

Abstract

Unilateral photochemical infarcts were produced in the hind limb sensorimotor neocortex of 243 rats by intravenous injection of the fluorescein derivative Rose Bengal and focal illumination of the intact skull surface. Facial contact stimuli governed the degree and recovery rate of contralateral tactile/proprioceptive forelimb placing reactions. Contralateral forelimb placing recovered, whereas hind limb placing was resistant to recovery. Infarcted rats displayed marked recovery of spontaneous limb usage (beam traversing). However, deficits in isolated tactile/proprioceptive hind limb placing reactions endured. Posttreatment with the class IV calcium antagonist flunarizine after neocortical infarction protected sensorimotor function in a dose-dependent manner. This protective effect may be due to the peculiar ionic channel blocking profile of flunarizine. Scopolamine hydrobromide reinstated contralateral placing errors in infarcted rats at a dosage that did not affect neurologically intact rats. The cognitive enhancer sabeluzole, a novel benzothiazol derivative, dose-dependently blocked the anticholinergic-induced deterioration of a sensorimotor deficit in rats.