STUDIES ON THE INTERRELATIONSHIP BETWEEN ENDOCRINE GLANDS

(II) AN EXPERIMENTAL STUDY ON THE RELATIONSHIP BETWEEN THE MALE GONAD AND THYROID

Abstract

In an attempt to elucidate the interrelationships among the pituitary, thyroid, and male gonad, adult male rats were used in various experiments. The following results were obtained.
1) Histological changes in the pituitary
After thyroidectomy an increase of basophilic cells was noted. T₃ administration caused a decrease, on the contrary. Administration of mercazol caused an increase of basophilic cells up to the third week. On the 6th week, a decrease was seen. No remarkable changes were seen in eosinophilic cells in any case. T₃ administration after thyroidectomy caused no marked histological changes in the pituitary. Upon orchidectomy, an increase of basophilic cells along the time course and appearance of castration cells were noted. After the third week, a decrease of chromophobe cells was noted. Six weeks after X-irradiation of the testicular region, an increase of basophilic cells was noted. Administration of testosterone propionate caused no remarkable change after 1 and 3 weeks. After 6 weeks, a decrease of basophilic cells was noted. Orchidectomy and administration of testosterone propionate gave rise to findings resembling those after orchidectomy in the course of one week. After 6 weeks, basophilic cells became less conspicuous especially with a decrease of large cells.
2) Histological changes of the thyroid
One and three weeks after mercazol administration the peripheral follicles were generally enlarged and the follicles in the internal side were small. The height of some epithelial cells was somewhat increased. After 6 weeks, the follicles were enlarged, colloid became dense, and epithelial cells tended to flatten. Upon T₃ administration, follicles were large and epithelial cells were flattened. Upon orchidectomy and X-irradiation of the testicular region, findings suggestive of hypofunction were noted. Administration of testosterone propionate in intact or orchidectomized animals rather gave rise to findings suggestive of hyperfunction.
3) Histological changes of the testes
Thyroidectomy caused a decrease of spermatogenesis but the administration of mercazol failed to cause remarkable change Administration of T₃ gave rise to a picture of hyperfunction of spermatogenesis 1 and 3 weeks later, but findings suggestive of inhibition of spermatogenetic function were obtained 6 weeks later. Administration of T₃ after thyroidectomy gave a picture of hyperfunction of spermatogenesis, suggesting the prevention of gonadal disturbance due to thyroidectomy through T₃ administration.
4) Changes in steroid 3β-ol-dehydrogenase activity in the testes
Thyroidectomy induced some decrease as compared qith the control. T₃ administration caused a rise in the activity after 1 week and a wuite intense activity was seen after 6 weeks. When T₃ was administered after thyroidectomy, elevation was also noted. However, administration of mercazol caused no remarkable changes. After l week of testosterone prppionate administration, pictures were similar to those in the controls. After 3 and 6 weeks, the picture was similar to or somewhat lower than the control. X-irradiation of the testicular region caused some rise after 3 and 6 weeks.
5) Changes of biochemical activity in the testicular tissue
Thyroidectomy caused a decrease of activities of SDH and LDH. T₃ administration caused elevation of both SDH and LDH activities, suggesting a metabolic pattern similar to that in other organs.
As in the preceding explanation, changes in the testes upon injury of the thyroid appear to be the secondary changes via the pituitary. On the other hand, profound changes were also seen in the metabolism of the testicular tissue, so that a direct influence of thyroid hormone on the testicular tissue should be taken into consideration in addition to the secondary changes via the pituitary.