Effects of intracerebroventricular prostaglandins E2 and F2alpha on the urine outflow, and a possible role of pgE2 as a modulator.

Effects of intracerebroventricularly (i.c.v.) injected PGE2 and PGF2alpha on the urine outflow were studied in ethanol-anesthetized rats. PGE2 and PGF2alpha, when injected i.c.v., caused diuresis which was followed by antidiuresis. Phentolamine, when perfused i.c.v., was an antidiuretic and inhibited the diuretic and antidiuretic effects of PGE2. Diphloretin phosphate inhibited both effects of PGE2. Polyphloretin phosphate (PPP) and propranolol blocked completely the PGE2-induced diuresis and consequently remarkable antidiuresis was observed after the combined treatments with PGE2 and PPP or propranolol. When PGE2 was perfused i.c.v., a sustained diuresis was obtained and antidiuretic effects of noradrenaline, gamma-aminobutyric acid and L-glutamate were potentiated, inhibited and unaffected by the perfusion with PGE2, respectively. It was indicated that the antidiuretic effect of PGE2 could be dissociated from the diuretic effect and that both effects were mediated through adrenergic mechanisms. The present result also suggested that central PGE2 might act as a modulator of some neurotransmitters involved in water metabolism.