INFLUENCE OF ANDROGEN ON HYPOTHYROIDISM IN RATS I. EFFECTS OF METHYLANDROSTENEDIOL ON THYROIDECTOMIZED RATS

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Abstract
Effects of MAD on rats under various conditions, particulary on thyroidectomized ones, were studied with special reference to the difference in growth between males and females. 1) When administration of 0.4mg/kg of MAD was started at 48 hrs. interval at the 4th week of age, simultaneously with thyroidectomy, depression of the growth of male rat and the acceleration of growth in the female were observed. 2) When the treatment of MAD had been commenced at the 1st week of age prior to the thyroidectomy conducted at the 4th week of age, the depression of male growth could not be observed, although the enhancement of female growth remained similar. Cessation of MAD administration at the 4th week of age did not bring an essential change to these results. 3) MAD treatment by itself did not exert a significant influence on the growth of intact rats, when given in a dose of 0.4mg/kg at 48 hrs, interval. In a does of 4 ing/kg, however, MAD decreased the male growth but increased the female growth. 4) The effect of MAD on castrated rat, in which the superiority of male to female in body weight had already been reduced considerably, was also similar to that on the intact rat, i. e., the difference between male and female became still smaller, if such a higher dose as 4mg/kg was administered. 5) MAD in a dose of 4 mg/kg at 48 hrs. interval, commenced simultaneously with hypophysectomy, showed a marked increase in growth of hypophysectomized rats, irrespective of sex, if operation was conducted at the 5th week of age, whereas no significant effect was observed in those operated at the 7th week of age. In conclusion, MAD showed an inhibitory effect on male growth and a stimulating effect on female growth. The absence of thyroid gland and/or reproductive organ, especially the former, seemed to enhance this trend.

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