The Production of hydrogen Sulphide and the Effects of Nitric Oxide (NO) and Low Oxygen Conditions in Intrauterine Tissues in Rats

Abstract

Hydrogen sulphide (H2S) is a gas signaling molecule which is produced endogenously from L-cysteine via the enzymes cystathionine beta-synthase (CBS) and cystathionine gamma-lyase (CSE). H2S may mediate hypoxic responses in vascular smooth muscle. H2S also appears to be a signaling molecule in mammalian non-vascular smooth muscle. Hypoxia is associated with pre-eclampsia where poor placental function can reduce the supply of oxygen and nutrients to the fetus resulting in intrauterine growth restriction (IUGR) and other placental dysfunctions. Hypoxia can also bring about other pre-eclamptic features such as the release of pro-inflammatory cytokines and oxidative stress.Hypoxic conditions can also reduce the uteroplacental perfusion, which may lead to inflammatory conditions i.e. oxidative stress. However, there are no reports to date on the production of H2S in reproductive tissues and the possible role of hydrogen sulphide in reproduction has not yet been fully investigated. It has been previously demonstrated that hydrogen sulphide relaxes uterine smooth muscle in vitro. We investigated the endogenous production of H2S in rat intrauterine tissues and the effectof NO and low oxygen condition on H2S production in intrauterine tissues. The production of H2S in rat intrauterine tissues was measured in vitro using a standard technique. The expression of CBS and CSE was also investigated in rat intrauterine tissues via western blotting. Furthermore, the effects of nitric oxide (NO) and low oxygen conditions on the production rates of hydrogen sulphide were investigated. The order of H2S production rates for rat tissues were: liver (488±28.9 nM/min/g) > uterus (310±36.7 nM/min/g) > fetal membranes (88.2±3.8 nM/min/g)> placenta (42.7± 6.8 nM/min/g). Under the effect of NO donor, NO significantly increased H2S production in rat fetal membranes only (from 88.2±3.8 nM/min/g to 103.2±7.4 nM/min/g). Under low oxygen conditions, production of H2S was significantly increased compared to room air oxygen conditions for rat liver (from 422±31.6 nM/min/g to 583±38.7 nM/min/g), uterus (from 328±11.8 nM/min/g to 5913±21.8 nM/min/g) and fetal membranes (from 78.2±9.1 to 189±17.1) , but not rat placenta. Western blotting detected the expression of CBS and CSE in all rat intrauterine tissues. Rat intrauterine tissues produce H2S in vitro possibly via CBS and CSE enzymes.