Central injection of galanin elicits feeding in satiated rats. We rece
ntly observed galanin-immunoreactive fibers in synaptic connection wit
h a population of beta-endorphin-immunopositive cell bodies and dendri
tes in the basal hypothalamus. Because beta-endorphin also stimulates
food intake, these morphological findings raised the possibility that
stimulation of feeding by galanin may, in part, be mediated by beta-en
dorphin release. First, we observed that ICV injection of galanin (1.5
-6.0 nmol) stimulated feeding in a dose-related fashion. Next, the eff
ect on food intake of the opioid receptor antagonist naloxone (20-200
mu g, ICV) administered immediately preceding galanin (3 nmol, ICV) wa
s evaluated. Galanin-induced feeding was suppressed by naloxone in a d
ose-dependent manner with a maximal suppression of 76% at the highest
naloxone dose. These findings support the existence of a functional li
nk between galanin and beta-endorphin and are in accord with the view
that stimulation of food intake by galanin may, in part, be mediated b
y increased beta-endorphin release.