EFFECT OF ALTERED THYROID AND ADRENAL ACTIVITY ON THE SEASONAL REPRODUCTION OF THE INDIAN PALM SQUIRREL, FUNAMBULUS-PENNANTI

Thiouracil and metyrapone administered during the progression phase of the annual reproductive cycle inhibited gonadal development in the In dian palm squirrel, Funambulus pennanti. In a further experiment, thes e drugs led to normal gonadal regression during the late breeding phas e. Thyroxine and corticosterone treatment, on the other hand, maintain ed the gonads continuously in breeding condition, unlike those of cont rols, which exhibited characteristic post-reproductive regression. Sin ce hypofunction of the thyroid and adrenal glands had inhibitory effec ts on the initiation of seasonal gonadal growth, and hyperactivity aff ects post-reproductive regression, it is suggested that an optimal lev el of hormones is required for the normal breeding cycle in this subtr opical mammal. The results are discussed in terms of an interrelations hip between the seasonal thyroid, adrenal, and gonad cycles under natu ral conditions.