title: Thyrotropin-releasing hormone reduces the plasma levels of beta-endorphin-like immunoreactivity in rats.
abstract: Effects of thyrotropin-releasing hormone (TRH) on the plasma beta-endorphin-like immunoreactivity (beta-Ep-LI) levels in rats have been studied. TRH (10 mg/kg) were injected i.v., and the animals were serially decapitated. The plasma beta-Ep-LI levels were measured by radioimmunoassay. Effects of TRH on beta-Ep-LI release from the anterior pituitary were also investigated by means of an in vitro experiment. The beta-Ep-LI content in the hypothalamus, pituitary gland or adrenal gland did not change significantly after TRH injection. The plasma beta-Ep-LI levels decreased significantly in a dose-related manner with a nadir at 40 min after the injection. In the hypophysectomized rats, the plasma beta-Ep-LI levels were lower than that of the control, and did not change significantly after TRH injection. beta-Ep-LI release from anterior pituitary in vitro significantly decreased after the addition of TRH to medium. These findings suggest that TRH may act on the pituitary gland to reduce plasma beta-Ep-LI levels in rats.
mesh_terms: D000311:Adrenal Glands / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D004723:Endorphins / Q000097:blood* / Q000378:metabolism; D007016:Hypophysectomy; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism; D008297:Male; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*; D001615:beta-Endorphin
chemical_list: D004723:Endorphins; D013973:Thyrotropin-Releasing Hormone; D001615:beta-Endorphin