GALANIN INHIBITS THE VASOLILATATORY BASALOCORTICAL CHOLINERGIC SYSTEMIN THE ANESTHETIZED RAT

IN Order to test the putative interaction between galanin and the vaso dilatatory basalocortical cholinergic system, anaesthetized ventilated rats received a microinjection into the substantia innominata of 0.9% NaCl, 50 nmol carbachol, 50 nmol carbachol and 200 ng galanin, or 200 ng galanin. Cerebral blood flow (CBF) was measured with [C-14]iodoant ipyrine by the tissue sampling technique immediately following the int racerebral infusions. Under coinjection conditions, the flow increases observed after carbachol microinjection in the ipsilateral temporal a nd frontoparietal cortices were found to be significantly reduced (-37 %, p less than or equal to 0.02 and -25%, p less than or equal to 0.05 respectively) compared with carbachol stimulated rats. The infusion o f galanin by itself had no effect on CBF. These results demonstrate th at galanin inhibits the vasodilatatory basalocortical cholinergic syst em and thus may possibly influence CBF by indirect mechanisms.