Effect of narcotic analgesics and naloxone on proestrous surges of LH, FSH and prolactin in rats.
Morphine (50 mg/kg), given at 12:00 h and 14:00 h to proestrous rats, completely inhibited the proestrous surges of serum luteinizing hormone (LH), follicle-stimulating hormone (FSH) and prolactin (Prl). However, when it was given at 16:00 h, the inhibitory effect of morphine (Mor) was decreased. Pethidine and nalorphine inhibited the proestrous surges, while pentazocine showed a weaker inhibitory effect. Naloxone (Nx), given simultaneously or 2 h after morphine (Mor), at 1/20 the dose of Mor, inhibited the blockade of the proestrous gonadotropin release exerted by Mor, while the onset of the surges was delayed when it was given 3 h after Mor.
D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D004347:Drug Interactions; D004971:Estrus; D005260:Female; D005640:Follicle Stimulating Hormone / Q000378:metabolism; D006065:Gonadotropins, Pituitary / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000378:metabolism; D008614:Meperidine / Q000494:pharmacology; D009020:Morphine / Q000494:pharmacology; D009269:Nalorphine / Q000494:pharmacology; D009270:Naloxone / Q000494:pharmacology*; D010423:Pentazocine / Q000494:pharmacology; D011247:Pregnancy; D011388:Prolactin / Q000378:metabolism; D051381:Rats
D000701:Analgesics, Opioid; D006065:Gonadotropins, Pituitary; D009270:Naloxone; D009020:Morphine; D011388:Prolactin; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D008614:Meperidine; D010423:Pentazocine; D009269:Nalorphine