Abstract
Suppression of the secretion of pituitary prolactin by the use of drugs (1-4) has been possible for only a few years, although increasing the secretion of this hormone by drugs has been feasible for many years (5). Ergocornine (Ergo) and/or 2-bromo-α-ergocryptine (CB-154), 2 chemically similar natural alkaloids extracted from ergot, have been reported to terminate early pregnancy (6), prevent deciduoma formation (7), suppress mammogenesis (4) and inhibit lactation and luteolysis (8) in rodents, all of which imply suppression of prolactin secretion. More recently, Ergo when administered to rats (1-4) and CB-154 when administered to cows (9) or humans (10) markedly reduced serum prolactin, as determined by radioimmunoassay, thus confirming and extending these earlier observations. Evidence indicates that the effects of these drugs are exerted at both the hypo-thalamic (1) and the pituitary (2, 3) levels.
Considerable attention has recently been given to a number of ergoline derivatives which also appear to suppress prolactin secretion (11). 6-Methyl-8-β-ergoline-ace-tonitrile (MEA) has been reported to interfere with pseudopregnancy (12), pregnancy (12) and mammogenesis (13) in mice and to prevent pregnancy (14) in rats. Recent evidence has also been provided showing that a chlorinated derivative of MEA, 2-chloro-6-methyl-8-β-ergoline-ace-tonitrile (Cl-MEA), is also capable of suppressing the secretion of this hormone (11).
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