Abstract
In an exploratory experiment it was found that doses of 10 to 100 R.U. of estrin (Progynon-B Schering)† failed to have the slightest effect on the behavior of 3 hypophysectomized female rats, although similar amounts consistently brought castrated females into heat. This suggested that estrin produced heat behavior by way of the pituitary and led to a series of experiments which, while somewhat inconclusive, are, nevertheless, of interest because they seem to show that progestin is not the immediate heat behavior hormone in the rat as Dempsey, Hertz and Young 1 believe is the case in the guinea pig.
The same 7 castrated female rats were used in each experiment. The method of measuring varying degrees of sexual excitability has been described elsewhere. 2
Injection of gonadotropic hormone (Prephysin Chappell)† in doses of 0.04 to 0.80 cc. had no effect, nor did luteinizing hormone† in doses ranging from 5 mg. given in a single injection up to 60 mg. given in 5 increasing doses over a 3-day period. However, 6 mg. of LH raised the sexual excitability of 2 unoperated females that happened to be spontaneously in a condition like that described as “constant estrus’ by Witschi and Pfeiffer. 3 The latent period for this reaction was about 4 hours, suggesting a much more direct action than that of estrin which has a latent period of 24 to 48 hours. These experiments pointed to the need of estrin as a preparatory agent for LH, although some doubt was thrown on such a requirement by the fact that high degrees of heat behavior were exhibited without any cornified cells in the smears of unoperated rats receiving 0.05 cc. Prephysin Chappel daily over long periods of time.
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