Central pipecolic acid increases food intake under ad libitum feeding conditions in the neonatal chick.
It has been demonstrated that L-pipecolic acid (L-PA) is a major metabolic intermediate of L-lysine in the mammalian and chicken brain. A previous study showed that intracerebroventricular (i.c.v.) injection of L-PA suppressed feeding in neonatal chicks, and the actions were associated with gamma-aminobutyric acid (GABA)-B receptor activation. It has been reported that endogenous L-PA in the brain fluctuated under different feeding conditions. In the present study, we investigated the effect of i.c.v. injection of L-PA on food intake in the neonatal chick under ad libitum feeding conditions. The food intake was increased by 0.5 or 1.0 mg L-PA under ad libitum feeding conditions contrary to previous studies using fasted birds. A hyperphagic effect of L-PA (0.5 mg) was attenuated by both GABA-A receptor antagonist (picrotoxin, 0.5 microg) and GABA-B receptor antagonist (CGP54626, 21.0 ng). These results indicate that a hyperphagic effect of L-PA is mediated by both GABA-A and GABA-B receptors and L-PA differentially affects food intake under different feeding conditions in the neonatal chick.
Takagi
Tomo
T
Laboratory of Advanced Animal and Marine Bioresources, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, 812-8581 Fukuoka-shi, Japan.
Tachibana
Tetsuya
T
Saito
Ei-Suke
ES
Tomonaga
Shouzou
S
Saito
Shin
S
Bungo
Takashi
T
Denbow
D Michael
DM
Furuse
Mitsuhiro
M
D000818:Animals; D000831:Animals, Newborn; D002645:Chickens; D004435:Eating / Q000187:drug effects*; D018756:GABA Antagonists / Q000494:pharmacology; D007276:Injections, Intraventricular; D008297:Male; D009943:Organophosphorus Compounds / Q000494:pharmacology; D010852:Picrotoxin / Q000494:pharmacology; D010875:Pipecolic Acids / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D011963:Receptors, GABA-A / Q000187:drug effects; D018080:Receptors, GABA-B / Q000187:drug effects; D013237:Stereoisomerism
D018756:GABA Antagonists; D009943:Organophosphorus Compounds; D010852:Picrotoxin; D010875:Pipecolic Acids; D011963:Receptors, GABA-A; D018080:Receptors, GABA-B; C107353:CGP 54626; C031345:pipecolic acid