Regulation of basal release of GABA by noradrenaline in the kitten visual cortex.

Abstract

To determine the modulatory effect of noradrenaline (NA) on basal release of gamma-aminobutyric acid (GABA), we measured the extracellular GABA with a brain microdialysis technique in the kitten visual cortex. Local infusion of NA through a cannula, which was implanted 2 mm away from the dialysis probe, gave rise to a marked increase in GABA release. This NA-induced GABA release was suppressed by tetrodotoxin, a sodium channel blocker, which was perfused at the probe site. The effect of NA was antagonized by pretreatment with metoprolol, a beta 1-selective antagonist. These results suggest that the cortical noradrenergic system may be involved in the regulation of basal GABA release that is possibly due to the activity of inhibitory neurones in the kitten visual cortex.