TIME COURSE OF EFFECTS OF MORPHINE ON HYPOTHALAMIC CONTENT OF LHRH AND SERUM TESTOSTERONE AND LH LEVELS OF MORPHINE-TOLERANT AND NONTOLERANT MALE RATS

  • 1 January 1978
    • journal article
    • research article
    • Vol. 233  (2) , 290-295
Abstract
Time course of the effects of morphine on the hypothalamic content of LHRH [luteinizing hormone releasing hormone] in both nontolerant and morphine-tolerant male rats was investigated in relation to the temporal changes of serum testosterone and LH [luteinizing hormone] levels. The hypothalamic LHRH content of the nontolerant rats was increased 8 h after the administration of morphine (100 mg/kg) when serum testosterone levels were depressed. The LHRH content of the tolerant rats was decreased during withdrawal of morphine for 48 h when the lowered serum testosterone and LH levels returned to within the control levels. The hypothalamic LHRH content does not necessarily reflect the release of LHRH. The release of hypothalamic LHRH is inhibited by the administration of morphine and is restored by the withdrawal of the narcotic.