Possible hormonal role of the angiotensin-like peptides in mammals' pineal gland.

An isorenin is synthetized in the pineal gland cells. The amount of isorenin as well as the synthesis of angiotensin I and II in the pineal gland depends on the circadian rhythm, osmotic stimuli and stimulation of the cervical sympathetic postganglionar fibres. Pineal angiotensin is released both into the blood and in the cerebrospinal fluid (CFS). The major site of the pineal angiotensin action are the circumventricular organs, the preiventricular receptors of the anterior hypothalamus and the epiphysis cerebri itself. Except its participation in regulating arterial pressure and the hydroelectrolytic metabolism, through its central effects on the brain, pineal angiotensin-like peptides also participate in the pool of circulating angiotensin and it may represent Farrell's pineal glomerulotropic factor.