The relationship between pineal and thyroid in response to the adrenocortical modulation is poorly understood. In the present study post pubertal male rats were treated with natural and synthetic corticoids and an antiadrenal agent mitotane. Hydroxycortisone was administered at a dose of 4 mg / 100 g b.w., dexamethasone 2 mg / 100 g b.w. and mitotane 3 mg / 100 g b.w. for fifteen consecutive days. Our data revealed that both the corticoids, hydroxycorticosterone and dexamethasone induced hyperactivity of pineal and thyrofollicular cell morphology. The functional relation between the cells of the pineal parenchyma and thyroid follicles were noted. Similar results were induced by mitotane, an antiadrenal agent. It is concluded, that our present study indicates a mutual relationship between the pineal and the thyroid gland karyomorphological and functional parameters in response to corticoids and an antiadrenal agent in post pubertal male rat (Rattus rattus).

The current investigation was undertaken to assess the pineal and thyroid gland cytophysiology and function in response to an exogenously altered steroid milieu following administration of a steroid hormone and non-steroidal antihormones. In the present study male rats (Rattus rattus) were injected with estradiol at a dose of 2 mg, testosterone 100 µg, tamoxifen 100 µg and flutamide 2 mg per 100 g b.w. intramuscularly for 15 consecutive days. Control rats were similarly injected with peanut oil vehicle intramuscularly for the same duration as the treated groups. The results indicated that pineal and thyroid gland response to estradiol and testosterone administration was opposite in nature. Estradiol induced significant hypertrophy of pineal and thyroid cytophysiology as indexed from significantly increased pineal and thyroid karyomorphological and associated parameter values, testosterone contrarily caused significant atrophy of pineal and thyroid cytophysiological parameters. Tamoxifen acted as a true estrogen agonist, whereas flutamide showed an androgen antagonist nature, thereby causing hyperactivity of pineal and thyroid karyomorphological and associated functions similar to that observed in estradiol treated rats, but contrary to that shown by testosterone induction in these rats.

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