Interplay between galanin and leptin in the hypothalamic control of feeding via corticotropin-releasing hormone and neuropeptide Y.

Bergonzelli, Gabriela E.; Pralong, François P.; Glauser, Micheline; Cavadas, Claudia; Grouzmann, Eric; Gaillard, Rolf C.; Bergonzelli, G E; Pralong, F P; Glauser, M; Cavadas, C; Grouzmann, E; Gaillard, R C

Over long periods, feeding and metabolism are tightly regulated at the central level. The total amount of nutrients ingested is thought to result from a delicate balance between orexigenic and anorexigenic factors expressed and secreted by specialized hypothalamic neuronal populations. We have developed a system of perifused hypothalamic neurons to characterize the relationships existing between the orexigenic peptide galanin and two other physiological modulators of feeding: neuropeptide Y (NPY) and corticotropin-releasing hormone (CRH). We demonstrated that galanin stimulates CRH and NPY secretion from hypothalamic neurons in a dose-dependent manner. Exposure to leptin for 24 h before galanin stimulation decreased NPY secretion by 30%, leaving the responsiveness of CRH neurons intact. These results suggest that CRH and NPY neurons participate to the intrahypothalamic signaling pathway of galanin, an observation that can explain the lower potency of galanin to stimulate food intake in vivo compared with NPY. The differential effects exerted by leptin on CRH and NPY suggest that there exists a subset of NPY neurons that are exquisitely sensitive to marked variations in leptin levels, and that the CRH neurons are less responsive to increases in leptin concentrations.

GALANIN; CORTICOTROPIN releasing hormone; NEUROPEPTIDE Y; SECRETION; HYPOTHALAMUS physiology; NEURAL physiology; RNA analysis; ANIMAL experimentation; CELL culture; COMPARATIVE studies; DRUG interactions; GENE expression; HYPOTHALAMUS; IMMUNOBLOTTING; IMMUNOHISTOCHEMISTRY; INGESTION; RESEARCH methodology; MEDICAL cooperation; NERVE tissue proteins; NEURONS; NEUROPEPTIDES; NUCLEOTIDE separation; POLYMERASE chain reaction; RATS; RESEARCH; LEPTIN; EMBRYOS; EVALUATION research; REVERSE transcriptase polymerase chain reaction

Diabetes, 2001, Vol 50, Issue 12, p2666

0012-1797

Academic Journal

10.2337/diabetes.50.12.2666