The role of basal forebrain in the primary cholinergic vasodilation in rat neocortex produced by systemic administration of cismethrin.

The pyrethroid insecticide cismethrin (9 mumol/kg) causes a large blood flow increase in cerebral cortex, without a parallel increase in metabolism. A unilateral lesion of the basal forebrain attenuated the blood flow increase in the cortex ipsilateral to the lesion but augmented that in the contralateral cortex. Cortical choline acetyltransferase was similarly affected. Atropine sulphate substantially reduced the flow increase and was additive to the lesion effects. Systemic cismethrin is thus capable of activating a cholinergic vasodilation in the cortex and, in the parietal cortex at least, a substantial proportion of the flow increase is mediated by extrinsic projections from the basal forebrain.