NORADRENALINE EFFECTS ON CULTURED RAT SENSORY NEURONS EXPOSED TO MORPHINE IN-UTERO OR IN-VITRO

Dorsal root ganglion (DRG) neurones cultured from newborn rats were ch ronically exposed to 1 mu M morphine. Untreated cells and in vitro mor phine treated cells were cultured for 1 or 2 weeks from control offspr ing while in utero morphine treated cells were cultured for 1 week fro m offspring of morphine dependent rats. Noradrenaline (1 mu M) was app lied by pressure ejection. Intracellular recordings measured the chang e in action potential duration (APD). Noradrenaline significantly decr eased the APD of 1-week-old untreated cells while the 2-week-old untre ated cells and the groups of morphine treated cells showed no signific ant change of APD following the drug application. Thus, newborn rat DR G neurones demonstrated a different sensitivity to noradrenaline with the culture duration or with morphine exposure.