Hydrogen sulfide alleviates placental injury induced by maternal cigarette smoke exposure during pregnancy in rats

Maternal cigarette smoke exposure (CS) during pregnancy is a well recognized causative factor for placental injury. Hydrogen sulfide (H2S), a gaseous signal molecule, has been shown to exert a protective effect against tissue injury in many organs. This study aimed to investigate whether H2S could alleviate CS-induced placental injury in rats. Pregnant SD rats were randomly divided into 4 groups: NaCl, CS, CS + NaHS (a donor of H2S) and NaHS. On gestational day 21, placental and fetal weights were measured. Placental H2S content was assessed by methylene blue method. Placental histological changes were examined by light microscopy and transmission electron microscopy. The results showed that administration of NaHS significantly attenuated CS-induced decrease in placental and fetal weights. Moreover, NaHS injection markedly alleviated CS-induced reduction in placental H2S content. Meanwhile, NaHS treatment obviously improved CS-induced morphological changes of placental junctional and labyrinthine zones. More notably, NaHS administration in CS rats was also found to ameliorate placental ultrastructural alterations, as indicated by decrease in the thickness of placental barrier, prevention of apical microvilli loss, alleviation of endoplasmic reticulum swelling and reduction in the number of vacuoles in trophoblast cells. Taken together, these findings demonstrate that administration of NaHS can alleviate CS-induced placental injuries in rats, suggesting that H2S may have therapeutic potential for treatment of placental injury caused by CS.