The effect of prostaglandins E2and F2αon orexin system expression in the porcine uterus during the peri-implantation period

The aim of this study was to evaluate the effect of prostaglandins E2(PGE2) and F2α(PGF2α) on orexins (OXA and OXB) secretion (ELISA), prepro-orexin (PPO) gene expression and the content of orexin receptors (OX1R, OX2R) mRNA (qPCR) and proteins (Western blot) in porcine endometrial and myometrial tissue slices during early pregnancy (days 10–28) and on days 10–11 of the oestrous cycle. On days 10–11 of pregnancy, prostaglandins (PGs) decreased the expression of the PPOgene and OXR gene and protein in the endometrium. On days 12– 13, PGs increased OXB secretion, PGE2enhanced OXA secretion, and PGF2αsuppressed PPOexpression. On days 15–16, both PGs inhibited PPOexpression and OXB secretion, and PGF2αincreased OXA release. On days 27–28, PGs decreased PPOmRNA and OX1R protein levels, PGE2decreased OX2R protein content, and PGF2αdecreased OXB secretion. On days 10-11 of the cycle PGs increased the expression of PPOmRNA and OX2R protein, whereas PGE2increased OX1R protein content. The effect of PGs on orexin system expression in the porcine myometrium was dependent on the animal physiological status and the concentrations of specific PGs. The study demonstrated that PGs exert regulatory effects on orexin system expression in the porcine uterus, which suggests that a local regulatory mechanism could be responsible for modulating uterine metabolism. The observed differences in PGs’ influence on orexin system expression could be attributed to changes in the sensitivity of the studied tissues, associated with the phase of the oestrous cycle, the stage of early pregnancy or PGs concentration.