Influence of pipecolic acid on the release and uptake of [3H]GABA from brain slices of mouse cerebral cortex.

Recently, pipecolic acid (PA) has been involved in the functioning of the GABAergic system. In the present work we have studied the effect of PA on GABA uptake and release in cerebral cortex slices. PA (100 microM) was able to increase the release of [3H]GABA (90%) stimulated by mild depolarization with 15 mM potassium. If during the labeling of the tissue with [3H]GABA, beta-alanine was present, PA also enhanced the release (42%). However, when nipecotic acid was present instead beta-alanine, no stimulation of [3H]GABA release by potassium was observed neither in the control nor in the presence of PA. Spontaneous release was not affected by PA in any of the experimental conditions tested. In uptake experiments, only when beta-alanine was present in the medium PA significantly diminished the uptake (36%) of [3H]GABA. These results suggest that the effect of PA is mostly at the presynaptic level, inhibiting the neuronal GABA uptake and/or enhancing its release.