Effects of galanin on 5-HT neurons in the rat CNS.

Intraventricular injections of the neuropeptide galanin were shown to induce a significant increase of endogenous 5-hydroxyindoleacetic acid (5-HIAA) levels in the occipital cortex, hippocampus and median eminence of rats. A general, but in most regions non-significant, tendency for increased 5-hydroxytryptamine (5-HT) levels was also observed. In view of the similar effects of galanin on 3,4-dihydroxyphenylacetic acid (DOPAC) levels in the median eminence and pons-medulla and in view of previous in vitro studies, these results are compatible with a presynaptic inhibitory effect of galanin on certain central 5-HT neurons of the rat.