Intracerebroventricular administration of GABA‐A and GABA‐B receptor antagonists attenuate feeding and sleeping‐like behavior induced by L ‐pipecolic acid in neonatal chicks

It has been demonstrated that L ‐pipecolic acid ( L ‐PA), a major metabolic intermediate of L ‐lysine ( L ‐Lys) in the mammalian and chicken brain, is involved in the functioning of the GABAergic system. A previous study has shown that intracerebroventricular (i.c.v.) injection of L ‐PA suppressed feeding and induced sleep‐like behavior in neonatal chicks; however, the precise relationship between the GABAergic system and L ‐PA has not been clarified. In the present study, the role of the GABA‐A or GABA‐B receptors in the suppression of food intake and induction of sleeping‐like behavior by L ‐PA was investigated. Chicks were injected i.c.v. with the GABA‐A antagonist picrotoxin or GABA‐B antagonist CGP54626 along with L ‐PA. Although suppression of food intake by L ‐PA was restored partially by co‐injection with CGP54626, but not picrotoxin, sleep‐like behavior induced by L ‐PA was suppressed significantly by both antagonists. These results suggested that L ‐PA activated both GABA‐A and GABA‐B receptors, and GABA‐B receptors alone contributed to food intake whereas both receptors contributed to sleep‐like behavior. © 2003 Wiley‐Liss, Inc.