Cysteamine induces depletion of both immunological and biological prolactin activity in the anterior pituitary and blood of the rat.
Previous studies have shown that cysteamine [2-aminoethanethiol (CSH)], given in vivo or in vitro, rapidly but reversibly depletes immunoreactive PRL from the anterior pituitary (AP) through a mechanism which, in vitro, does not appear to involve the dopamine (DA) receptor. In the present investigation, these effects of CSH were explored further with emphasis on determining whether CSH; (1) depletes biological as well as immunological PRL activity from the AP and blood, (2) has effects on plasma PRL in chronically cannulated male rats, (3) alters the PRL response to drugs which stimulate the secretion of the hormone, and (4) acts in vivo via DA receptors to deplete PRL. CSH produced a dose-dependent depletion of both immunological and biological PRL activity from the AP and blood. In chronically cannulated animals, PRL levels in the plasma were undetectable 90 min after CSH administration and remained so for 4 h. However, by 24 h plasma PRL in treated animals had returned to control levels. The PRL response to both domperidone and morphine was virtually abolished in CSH-treated animals. Blockade of DA receptors by pretreatment with domperidone did not alter the ability of CSH to reduce AP PRL stores. These results indicate that CSH: 1) alters both biological and immunological PRL activity by a rapid but reversible effect, and 2) circumvents the DA receptor to deplete pituitary PRL content. Thus, CSH or similar compounds may serve as a prototype for a new class of drugs which can be used in the treatment of hyperprolactinemia.
D000818:Animals; D003543:Cysteamine / Q000494:pharmacology*; D004294:Domperidone / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D008297:Male; D009020:Morphine / Q000494:pharmacology; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism*; D011388:Prolactin / Q000097:blood / Q000276:immunology / Q000378:metabolism*; D011863:Radioimmunoassay; D051381:Rats; D011954:Receptors, Dopamine / Q000502:physiology
D011954:Receptors, Dopamine; D004294:Domperidone; D003543:Cysteamine; D009020:Morphine; D011388:Prolactin