DURATION AND FREQUENCY OF MULTIUNIT ELECTRICAL-ACTIVITY ASSOCIATED WITH THE HYPOTHALAMIC GONADOTROPIN-RELEASING-HORMONE PULSE-GENERATOR IN THE RHESUS-MONKEY - DIFFERENTIAL-EFFECTS OF MORPHINE

The effects of morphine on the frequency and duration of the characteristic bursts or ’volleys’ of multiunit electrical activity (MUA) associated with pulsatile pituitary luteinizing hormone (LH) secretion were studied in unanesthetized ovariec- tomized rhesus monkeys bearing bilateral arrays of electrodes implanted in the mediobasal hypothalamus. Morphine administration resulted in a dose-dependent decrease in MUA volley duration and frequency. When morphine was infused at 10 μg/kg/h, the inhibiting effect on volley duration was observed without a change in volley frequency. It is concluded that the frequency and duration of hypothalamic MUA volleys associated with pulsatile LH secretion may be independently regulated. © 1990 S. Karger AG, Basel.