Effect of intracerebroventricular injection of l-pipecolic acid on gab a concentrations in brain sites of neonatal chicks

L-pipecolic acid (L-PA) is a major metabolic intermediate of L-lysine in the mammalian and chicken brain, which enhances y-amino butyric acid (GABA) release and inhibits GABA re-uptake. Our previous study showed that intracerebroventricular (i.c.v.) injection of L-PA suppressed feeding and induced sleep-like behavior in neonatal chicks. These behaviors which are associated with the GABA system, suggest a link between L-PA and GABA. The present study was designed to determine GABA concentrations in several chick brain sites after i.c.v. injection of L-PA. Unexpectedly, L-PA tended to decrease GABA concentrations in all brain sites tested except for the pons-medulla oblongata and the decrease was largest in the optic lobe. These results, taken together with previous findings, support a link between i.c.v. L-PA and extracellular GABA concentrations.