下垂体剔出幼若雄ラットの生殖器系に対する妊馬血清性性腺刺戟ホルモン(PMSG)の作用

抄録

The biological properties of PMSG are thought to be similar to those of the unfractionated pituitary compound of FSH and ICSH. However, it was proved in the present study that effects of PMSG on immature male reproductive organs is not identical with the pituitary GTH.
The Wistar-Imamichi rats8) weighing 28-40 g at the age of 21-23 days were hypophysectomized through parapharyngeal route. The same assay method reported before6) was used. The results was compared with those obtained by ICSH6) and HCG7) by means of the prostate units (the universal biological unit for comparing the activity of gonadotrophins derived from any source).
Testicular weight increased at the small dose (1.43Pr. U.) of PMSG and plateaued at total dose of about 300 Pr. U. ICSH was slightly effective than PMSG on testicular weight, although ICSH did not give to attain the plateaued weight. Tested by unfractionated sheep pituitary GTH (Vetrophin) however, testicular weight initiated to increase at small dose than ICSH and plateaued on the same level as PMSG at smaller dose (32-64 Pr. U.).
Accordingly, the effect of PMSG to increase the testicular weight of 21 day old rats is weaker than that of the pituitary GTH. In all of these cases, the interstitial cells were stimulated, but the seminiferous tubles were differentiated at only the stage of spermatocyte formation. Accessory organs (epididymides, seminal vesicles and ventral prostate) were extremely stimulated by PMSG as well as HCG. Their plateaued weights were obtained at relatively small doses (about 3 Pr. U. in epididymides and about 20 Pr. U. in seminal vesicles and ventral prostate). By ICSH treatment, the seminal vesicles did not stimulated at higher dose (50 Pr. U.), however, at the more dose of the unfractionated sheep pituitary GTH (about 250 Pr. U.) the weight of seminal vesicles increased to the highest levels in the cases of PMSG and HCG treatment. Similarly, the ventral prostate did not responded conspicuously to ICSH. The weight of ventral prostate of animals received more dose of ICSH (50 Pr. U.) was almost twice of hypophysectomized controls, i. e., the same as animals treated with 1 Pr. U. In this case, higher doses of the unfractionated sheep GTH (about 125-250 Pr. U.) increased the weight of ventral prostate up to the same levels as PMSG and HCG (4-5 times of controls).
It may be said that the distinct difference of PMSG to pituitary GTH is the effect of androgen secretion. The stimulative effect of pituitary GTH to secret the testicular androgen is not conspicuous in immature animals. On the contrary, PMSG having the specific properties of the placental GTH like HCG acceralates powerfully the androgen secretion not only in adult but in immature animals. These differences would be accounted for the intrinsical difference, but not the varied rate of content of FSH and ICSH.