OS064. Contribute of the L-cysteine/ H2S pathway in placenta homeostasisin hypertensive disorders

Introduction Hydrogen sulfide (H 2 S) is considered the third endogenous gas transmitter besides nitric oxide and carbon monoxide [1]. It is produced from L-cysteine or L-methionine via the enzymes cystathionine beta-synthase (CBS) and cystathionine gamma-lyase (CSE). H 2 S is involved in the control of vascular homeostasis, having either relaxant or contractant effect on smooth muscle cells. The H 2 S involvement in rat and human intrauterine tissues has also been shown [2]. Objectives The aim of our study was to investigate the L-cysteine/ H 2 S pathway in rat and human placenta in hypertensive state. Methods Placental samples were collected from spontaneous hypertensive rats (SHR) and normotensive rat (Wistar Kyoto; WKY). In parallel, placental samples were collected from 10 pre-eclamptic women and 5 controls after caesarean sections. Pre-eclamptic women were divided into two subgroups: Group1 (women who developed Early Preeclampsia, n =4); Group2 (women who developed Late Preeclampsia, n =6). The expression of CBS and CSE was evaluated in sample tissues by Western blotting analysis. The enzymatic activity was assessed in basal and stimulated (L- cysteine) condiction by a colorimetric assay. Statistical analysis was performed by using Student's t test. P Results The expression of CBS and CSE in placenta of SHR rats were significantly reduced ( p 2 S production resulted significantly ( p In human placenta, the basal H 2 S production was similar in the three groups; interestingly the H 2 S production by adding L-cysteine, was higher in Late Preeclampsia compared to control group. Conclusion H 2 S was produced in rat and human placenta. CBS and CSE, the enzymes involved in the production of H 2 S, were down-regulated in SHR rats and, as a consequence the H 2 S production was significantly reduced. Starting from these data, we tried to analyze the role of hydrogen sulfide in preeclampsia to assess the contribute of this gas transmitter in the development of this condition. Unexpectedly, preliminary data demonstrated that in women developing Late Preeclampsia there was an higher production of H 2 S after stimulation with L-cysteine, not revealed in Early Preeclampsia or in healthy control group. Our results indicated that the L-cysteine/H 2 S pathway could contribute to the development of preeclampsia condition.