Some endocrine effects of blinding and anosmia in adult male rats with observations on pineal melatonin

Although removal of the eyes or of the olfactory bulbs alone had relatively little influence on the endocrine and reproductive organs of adult male rats, when both operations were done in the same animal the testes, seminal vesicles, coagulating glands, ventral lobes of the prostate and pituitary gland exhibited significant regression within 8 weeks. The atrophic responses of these organs did not develop in similarly treated pinealectomized rats, however. Anosmia, alone or combined with eyelessness, also significantly reduced body weights, an effect not reversed by pineal removal. Pineal levels of HIOMT were significantly elevated in both blinded and blinded, anosmic rats, but anosmia alone did not stimulate the activity of the enzyme. Pineal melatonin content, estimated by bioassay, was usually greater in untreated and anosmic rats killed during darkness than when similarly treated animals were killed in the light. Blinded and blinded, anosmic rats were killed either at their peak of circadian locomotor activity or at the midpoint of their inactive phase. Invariably, pineals of rats killed during their active phase contained more melatonin than those killed during their inactive period.