The effect of cysteamine, cystamine, and the structurally related compounds taurine, N-acetyl-cysteine, and D-penicillamine on plasma prolactin levels in normal and estrogen-primed hyperprolactinemic rats.
Studies were undertaken to evaluate the effects of cysteamine (CSH), cystamine (CS-S), N-acetyl-cysteine, D-penicillamine, and a major metabolite of CSh, taurine, on plasma PRL levels in normal and estrogen-primed hyperprolactinemic rats. Both CSH and CS-S caused a marked decrease in plasma PRL concentration in hyperprolactinemic rats. The effects of CSH and CS-S lasted for at least 6 h but returned toward pretreatment levels 24 h later. In normal rats a fall in basal plasma PRL concentration was not readily observed but after stimulation with TRH or metaclopramide, PRL secretion elicited by these stimuli was markedly inhibited by CSH and CS-S. The response to TRH or MCP 24 h after treatment with CSH was variable with CS-S appearing to cause an unexpected increase in PRL release in response to TRH or metaclopramide. The structurally related compounds, taurine, N-acetyl-cysteine, and D-penicillamine did not cause any reduction of plasma PRL levels in hyperprolactinemic rats. This may be due, in the case of taurine, to a loss of the free sulfydryl group, in the case of N-acetyl-cysteine, a change in basicity because of a carboxyl group and derivatization of the amino group and D-penicillamine, again a change in basicity due to a free carboxyl group as well as an altered structural relationship between the free amino and sulfydryl groups. These studies indicate that CSH and CS-S by possible reduction to CSH cause a reversible depletion in plasma PRL in normal and hyperprolactinemic rats. Because both substances inhibit different receptor-mediated stimuli, their mechanism of action is likely to be mediated at a common locus involved with the synthesis and release of PRL.
D000111:Acetylcysteine / Q000494:pharmacology*; D000818:Animals; D003538:Cystamine / Q000494:pharmacology; D003543:Cysteamine / Q000494:pharmacology*; D004958:Estradiol; D006966:Hyperprolactinemia / Q000097:blood* / Q000139:chemically induced; D008297:Male; D008787:Metoclopramide / Q000494:pharmacology; D010396:Penicillamine / Q000494:pharmacology*; D011388:Prolactin / Q000097:blood; D051381:Rats; D013654:Taurine / Q000494:pharmacology*; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology
D013654:Taurine; D004958:Estradiol; D003543:Cysteamine; D013973:Thyrotropin-Releasing Hormone; D011388:Prolactin; D010396:Penicillamine; D008787:Metoclopramide; D003538:Cystamine; D000111:Acetylcysteine