Inhibitory effect of DUP-753 on the drinking responses of rats to central administration of noradrenaline and angiotensin II and to dehydration

We investigated the effect of losartan (DUP-753) on the dipsogenic responses produced by intracerebroventricular (icv) injection of noradrenaline (40 nmol/mu l) and angiotensin II (ANG II) (2 ng/mu l) in male Holtzman rats weighing 250-300 g. The effect of DUP-753 was also studied in animals submitted to water deprivation for 30 h. After control injections of isotonic saline (0.15 M NaCl, 1 mu l) into the lateral ventricle (LV) the water intake was 0.2 +/- 0.01 ml/h. DUP-753 (50 nmol/mu l) when injected alone into the LV of satiated animals had no significant effect on drinking (0.4 +/- 0.02 ml/h) (N = 8). DUP-753 (50 nmol/mu l) injected into the LV prior to noradrenaline reduced the water intake from 2.4 +/- 0.8 to 0.8 +/- 0.2 ml/h (N = 8). The water intake induced by injection of ANG II and water deprivation was also reduced from 9.2 +/- 1.4 and 12.7 +/- 1.4 ml/h to 0.8 +/- 0.2 and 1.7 +/- 0.3 ml/h (N = 6 and N = 8), respectively. These data indicate a correlation between noradrenergic pathways and angiotensinergic receptors and lead us to conclude that noradrenaline-induced water intake may be due to the release of ANG II by the brain. The finding that water intake was reduced by DUP-753 in water-deprived animals suggests that dehydration releases ANG II, and that AT(1) receptors of the brain play an important role in the regulation of water intake induced by deprivation.

Erbium- and ytterbium-doped sol-gel SiO2-HfO2 crack-free thick films onto silica on silicon substrate

Aware of the difficulties in applying sol-gel technology on the preparation of thin films suitable for optical devices, the present paper reports on the preparation of crack-free erbium- and ytterbium-doped silica: hafnia thick films onto silica on silicon. The film was obtained using a dispersion of silica-hafnia nanoparticles into a binder solution, spin-coating, regular thermal process and rapid thermal process. The used methodology has allowed a significant increase of the film thickness. Based on the presented results good optical-quality films with the required thickness for a fiber matching single mode waveguide were obtained using the erbium- and ytterbium-activated sol-gel silica:hafnia system. The prepared film supports two transversal electric modes at 1550 nm and the difference between the transversal electric mode and the transversal magnetic mode is very small, indicating low birefringence. Photoluminescence of the I-4(13/2) -> I-4(15/2) transition of erbium ions shows a broad band centered at 1.53 mu m with full width at a half maximum of 28 nm. Up-conversion emission was carried out under different pump laser powers, and just one transition at red region was observed. (c) 2006 Elsevier B.V. All rights reserved.