Role of brain prostaglandins in the control of vasopressin secretion in the conscious rat.

Administration of 10 micrograms prostaglandin D2 (PGD2), the primary PG identified in the rat brain, into the lateral cerebral ventricle of conscious rats resulted in a significant elevation in the plasma vasopressin (AVP) concentration, without a change in mean arterial blood pressure or heart rate. The central administration of indomethacin (100 micrograms) resulted in a significant attenuation of the AVP response to a peripheral osmotic stimulus (iv 2.5 M NaCl; 100 microliters/kg X min for 30 min), but had little effect on the AVP response to hemorrhage (two successive 10% reductions in the estimated blood volume). Administration of another PG synthetase inhibitor, meclofenamate (100 micrograms, into the lateral cerebral ventricle), resulted in a significant attenuation of the AVP response to both the osmotic stimulus and hemorrhage. It is concluded that brain PGs play a central role in the control of AVP secretion.