The effect of reserpine and alpha-methyldopa on the analgesic action of morphine in the mouse

In the tail clip test, reserpine inhibited the analgesic action of morphine, and this action of reserpine was prevented by pretreatment with α-methyldopa. In the hot plate test reserpine potentiated the action of morphine, and α-methyldopa pre- treatment had no inhibitory action on reserpine. α-Methyldopa alone, and in combination with reserpine, showed an analgesic action in the hot plate test.