GALANIN RECEPTOR ACTIVATION ATTENUATES NOREPINEPHRINE RELEASE FROM RAT SPINAL-CORD SLICES

Galanin and norepinephrine both act on sensory neurons in the rat spin al cord dorsal horn. We looked the effects of galanin on the basal and electrically-evoked release of [H-3]norepinephrine from slices of the dorsal spinal cord. 0.1 to 1.0 muM reduced the basal efflux by maxima l 10 % and the stimulation-evoked release in a concentration-related m anner by maximal 27 %. In the presence of 0.1 muM galanin receptor ant agonist (M-15) reduction of basal efflux persisted but significant eff ects on the stimulation-evoked release were no longer observed. The an tagonist, given alone, was without effect on the release. Thus galanin can reduce the stimulation-evoked norepinephrine release from spinal cord dorsal horn nerve terminals by an action on galanin receptors, ho wever, the release seems not to be tonically inhibited by galanin.