EFFECT OF CONTINOUS LIGHT AND DARKNESS EXPOSURES ON THE PITUITARY-GONADAL AXIS AND THYROID ACTIVITY IN MALE RATS

The effects of constant light and dark exposure of pubertal male rats on the pituitary-gonadal axis and thyroid activity were studied. The indices of thyroid activity were weight of the thyroid gland, estimation of serum levels of thyroxine (T4) by radioimmunoassay (RIA) technique and histological studies of the thyroid gland. The indices of gonadal activity chosen were weight and histological study of the testes and determination of serum levels of Luteinizing hormone (LH) and Follicle Stimulating Hormon (FSH) by RIA technique. In the rats exposed to continuous light, the weight of the thyroid gland increased significantly (P