Is angiotensin a new pineal hormone?

An isorenin is synthetized in the pineal gland cells. For the synthesis of angiotensin I and II a supply of alpha2 globulin renin substrate is necessary. The amount of isorenin as well as of angiotensin I and II in the pineal gland depends on the circadian rhythm, the sleep-wakefulness cycle, osmotic stimuli, stimulation of the sympathetic postganglionar fibres which innervate the pineal gland and it is increased in some diseases, as hereditary diabetes insipidus and spontaneous hypertension in rat. Pineal angiotensin is released both into the blood and into the cerebrospinal fluid (CSF). The major sites of action are the circumventricular organs, the periventricular receptors of the anterior hypothalamus and the epiphysis cerebri itself. Beside its participation in the regulation of arterial pressure and of the hydroelectrolytic metabolism through its direct effects on the brain, pineal angiotensin also participates in the pool of circulating angiotensin and it may represent Farrell's pineal glomerulotropic factor.