Paraventricular nucleus administration of DuP753 or PD123319 inhibits the effects of angiotensin on water and sodium intake

ABSTRACT

We determined the effects of DuP753 and PD123319 (both nonpeptides and selective antagonists of the AT1 and AT2 angiotensin receptors, respectively), and [Sar(l), Ala(8)]ANG II (a non-selective peptide antagonist of angiotensin receptors)on water and 3 per cent NaCl intake induced by administration of angiotensin II (ANG II) into the paraventricular nucleus (PVN) of sodium-depleted Holtzman rats weighing 250-300 g. Twenty hours before the experiments, the rats were depleted of sodium using furosemide (10 ng/rat, sc). The volume of drug solution injected was 0.5 mul over a period of 10-15 sec. Water and sodium intake were measured at 0.25, 0.5, 1.0 and 2.0 h. Pre-treatment with DuP753 (l4 rats) at a dose of 60 ng completely abolished the water intake induced by injection of 12 ng of ANG II (15 rats) (6.4 ñ 0.6 vs 1.4 ñ 0.3 ml/2 h), whereas [Sar(l), Ala(8)]ANG II (l2 rats) and PDl23319 (10 rats) at the doses of 60 ng partially blocked water intake (6.4 ñ 0.6 vs 2.9 ñ 0.5 and 2.7 ñ 0.2 ml/2 h, respectively). In the same animals, [Sar(l), Ala(8)]ANG II, DuP753, and PDl23319 blocked the sodium intake induced by ANG II (9.2 ñ 1.6 vs 3.3 ñ 0.6, 1.8 ñ 0.3, and 1.4 ñ 0.2 ml/2 h, respectively). These results indicate that both DuP753 and PD123319, administered into the PVN, blocked the water and sodium intake induced by administration of ANG II into the same site.