A Pharmacological Ejaculation Test for Bio-Assay of Male Sex Hormone

Abstract

Mammalian tests for the male hormone are preferable to bird tests, a fact which has been stressed by Loewe and Voss since the discovery of the hormone 1 , 2 , 3 and has gained general recognition through the differentiation of two active principles—testosterone and androsterone (Laqueur, 4 Rucicka 5 ). However, mammalian tests in use are unsatisfactory, in that not all of the functions governed by the hormone are observed. This objection does not apply to an ejaculation test since the latter requires the integrity of numerous central and peripheral sex functions. The production of ejaculation by electrical stimulation has been employed in a procedure for detecting the action of the male hormone on the guinea pig, 6 but it has not been developed into a quantitative method, and it is difficult to elicit the response in the smaller rodents. In the mouse the production of ejaculation by the action of drugs 7 provides an excellent method for studying the ejaculatory function. This method not only detects the action of male hormones, but supplies a means for their bioassay. The experiments reported here deal with its use in a method of bio-assay.

The experiments were performed on adult albino mice. Ejaculation was elicited by the pernostone-yohimbine technic which will be described in detail elsewhere. 7 This consisted essentially of the hypodermic injection of 83 mg./kg. of pernoston in a 0.67% solution followed in 12 minutes by the subcutaneous injection of 10 mg./kg. of yohimbine sulfate in a 0.5% aqueous solution; 5 minutes later the mouse is brought into a lateral position. Ejaculation occurs within 5 to 40 minutes. Only animals which gave a prompt ejaculatory response in the pernostone-yohimbine test before, but not after castration, were used for the hormone injections. After experimenting with various types of hormone administration, preference was given to a slow method, i. e., one daily injection on 5 successive days, A few series with a rapid method—3 injections within 36 hours—will be briefly mentioned. The animals were repeatedly subjected to the pernostone-yohimbine test at intervals of from 2 to 4 days both during and after the period of hormone injection. Testosterone and testosterone propionate, and in further experiments testosterone acetate and androsterone, were used for the hormone treatment. All substances∗ were injected in a solution of oil, the volume not exceeding 0.5 cc. The experiments are summarized in Table I.