The effects of glycine on the release of [3H]noradrenaline ([3H]NA) have been investigated using rat hippocampus slices previously labeled with the radioactive catecholamine. Glycine (30-1000 microM) produced a potent and concentration-dependent increase of the release of [3H]NA evoked by 12 mM KCl. The effect of 1000 microM glycine was totally antagonized by 3 microM strychnine suggesting that, in rat hippocampus, glycine may regulate the release of NA by activating a receptor of the strychnine-sensitive subtype.