The neuropeptide galanin (GAL) has been found to elicit feeding after injection into the paraventricular hypothalamic nucleus (PVN), where it coexists with norepinephrine (NE), a neurotransmitter believed to be important in the control of natural feeding behavior. Using pharmacological tools, this study investigated the possibility that PVN GAL influences food intake via its direct interaction with the noradrenergic system localized in this nucleus. Tests with α-adrenergic receptor blockers demonstrated that GAL-induced feeding, similar to NE-stimulated feeding, depends specifically upon functional α2-receptor sites. Further, experimentation with the catecholamine synthesis inhibitors, α-methyl-p-tyrosine and Fla-63, suggested that GAL's action also depends upon the release of endogenous NE. This is in contrast to another hypothalamic peptide, neuropeptide Y, which is also a strong stimulant of food intake and coexists with NE in the PVN, Neuropeptide Y remains effective in eliciting feeding in the presence of α2-receptor antagonists and catecholamine-synthesis inhibitors, suggesting that, unlike GAL, it can act independently of endogenous NE. © 1990.
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