The pineal gland and aldosterone

¹ Laboratory of Clinical Physiology, McLean Hospital, Waverly; and Harvard University Schools of Dental Medicine, Medicine, and Public Health, Boston, Massachusetts

It has recently been suggested that the canine pineal gland secretes a hormone which stimulates the adrenal cortex to release aldosterone. The following experiments were undertaken to determine what effect pinealectomy or administration of bovine pineal extracts has on certain physiologic variables associated with aldosterone activity in rats: a) the relative size of the zona glomerulosa, compared with total adrenal area, was determined planimetrically in 25 female rats treated with pinealectomy, pineal extracts, or both; b) urinary potassium excretion was measured in 4 pinealectomized and 4 control female rats; c) the elective saline intakes, at concentrations ranging from 0 to 3.0%, were measured in 5 male control rats and in 5 animals given 1.0 ml/day of pineal extract. Pinealectomy or pineal extract had no effect on any of these variables, suggesting that the pineal gland does not regulate aldosterone secretion in the rat.