Photoinduced water splitting with oxotitanium tetraphenylporphyrin.

Photocatalytic splitting of water was investigated in a heterogeneous system consisting of micro-crystallites of oxotitanium tetraphenylporphyrin deposited on fused silica plates, immersed in water and excited within the visible range of their absorption spectra. The water photolysis was evidenced by the spectroscopic detection of hydroxyl radicals generated in the reaction. The experimental results confirm the mechanism of water splitting and generation of OH˙ radicals proposed theoretically by Sobolewski and Domcke [Phys. Chem. Chem. Phys., 2012, 14, 12807] for the oxotitaniumporphyrin-water complex. It is shown that photocatalytic water splitting occurs in pure water, and neither pH-bias nor external voltage is required to promote the reaction.

Galanin influences on vasopressin and oxytocin release: in vitro studies.

Galanin (Gal) acts in the central nervous system as the neuromodulator of the hypothalamo-neurohypophysial system function. Present investigations in vitro were undertaken to study the influence of Gal, added to the incubative media at the concentrations of 10(-10), 10(-9), 10(-8) or 10(-7) M, on AVP and OT release from isolated rat hypothalamus (Hth), neurohypophysis (NH) and hypothalamo-neurohypophysial system (Hth-NH). The present results showed that Gal at the concentrations of 10(-10), 10(-9) and 10(-8) M inhibited basal AVP secretion from the all incubated tissues as well as OT release from the NH and Hth-NH explant. On the contrary, 10(-10) M Gal was the reason of intensified basal hypothalamic OT secretion. The presence of Gal at the concentrations of 10(-10) and 10(-8) M in the incubative media enriched in potassium ions excess was the cause of diminished AVP release from the NH and from the Hth-NH explant, respectively. Any effect of Gal on AVP release from the Hth has been observed. All the concentrations of Gal did not exert any effect on OT release from the NH as well as Hth-NH explants. However, the K(+)-evoked OT release from the Hth was distinctly intensified under influence of 10(-10)M as well as 10(-8) M Gal. It may be concluded that: * Gal modifies AVP and OT release in vitro at every level of Hth-NH system. * Gal has been supposed to perform the role of central inhibitory neuromodulator for AVP release from the Hth-NH system. * Gal exerts inhibitory effect on OT release in vitro from NH as well intact Hth-NH system but stimulatory influence on OT secretion at the level of Hth.

Thyrotropin-releasing hormone modulates vasopressin and oxytocin synthesis and release from the hypothalamo-neurohypophysial system of different age male rats.

Thyrotropin-releasing hormone (TRH) is engaged in the modulation of the hypothalamo-neurohypophysial system activity. Effects of repeated intravenously injections of TRH in a dose of 100 ng/100 g b.w. on vasopressin (VP) and oxytocin (OT) biosynthesis and release from the hypothalamo-neurohypophysial system was investigated in rats in different age (1-, 3- or 7-months of the life). To estimate the biosynthesis rate of both neurohormones the colchicine procedure was used (the dose of 5 microg/5 microl icv 20 hours before the decapitation). It has been observed that vasopressin synthesis in the hypothalamus increased gradually with maturation of rats, while OT biosynthesis decreased in the same animals. Hypothalamic biosynthesis rate of VP and OT is most effective in youngest rats and declines during the adolescence of animals. Thyrotropin-releasing hormone directly affects VP-ergic and OT-ergic hypothalamic neurons activity and both neurohormones biosynthesis process. This effect, however, is opposed: TRH acts as a stimulator of vasopressin biosynthesis most of all in young male rats and as an inhibitor for oxytocin biosynthesis especially in mature animals.