PARTICIPATION OF GALANINERGIC NEUROTRANSMISSION AT THE PARAVENTRICULAR HYPOTHALAMIC NUCLEUS IN THE SUPPRESSION OF BARORECEPTOR REFLEX RESPONSE BY LOCUS-CERULEUS IN THE RAT

We evaluated the potential participation of galanin (GAL) at the parav entricular nucleus of hypothalamus (PVN) in the suppression of barorec eptor reflex (ERR) response by locus ceruleus (LC), using adult male S prague-Dawley rats anesthetized with pentobarbital sodium. Microinject ion of GAL (100 pmol) bilaterally into the PVN significantly depressed the ERR response. This suppressive effect was appreciably antagonized when GAL (100 pmol) and GAL antiserum (1:20) were coadministered into the bilateral PVN. Whereas bilateral microinjection of GAL antiserum into the PVN by itself elicited minimal effect, it nevertheless signif icantly attenuated the suppressive effect of either electrical or chem ical activation of LC on the ERR response. Pretreatment with the same amount of normal rabbit serum (1:20), on the other hand, was ineffecti ve. These results suggest that a galaninergic projection from the LC t o PVN may participate in the suppression of BRR response by this dorsa l pontine nucleus.