Morphine Inhibits Electrically Stimulated Noradrenaline Release from Slices of Rat Medial Preoptic Area

Abstract

Experiments were undertaken to investigate whether the release of noradrenaline (NA) in the preoptic area of female rats is modulated by opiate mechanisms. Slices (300 microns) of preoptic area were incubated individually after loading with 3H-NA and then subjected to electric field stimulation. Morphine (10 microM) significantly reduced the amount of NA released in response to electrical stimulation, an effect that was completely prevented by simultaneous exposure to equimolar naloxone. This inhibitory action of morphine was not dependent upon prior exposure to oestrogen.