Chemerin Affects P4 and E2 Synthesis in the Porcine Endometrium during Early Pregnancy

Abstract

Chemerin, belonging to the adipokine family, exhibits pleiotropic activity. We hypothesised that the adipokine could be involved in the regulation of steroidogenesis in the porcine endometrium. Thus, the aim of this study was to determine the effect of chemerin on the key steroidogenic enzyme proteins' abundance (Western blot), as well as on P₄ and E₂ secretion (radioimmunoassay) by the porcine endometrium during early pregnancy and the mid-luteal phase of the oestrous cycle. Moreover, we investigated the hormone impact on Erk and Akt signalling pathway activation (Western blot). Chemerin stimulated E₂ production on days 10 to 11 of pregnancy. On days 10 to 11 and 15 to 16 of gestation, and on days 10 to 11 of the cycle, chemerin enhanced the expression of StAR and all steroidogenic enzyme proteins. On days 12 to 13 of pregnancy, chemerin decreased StAR and most of the steroidogenic enzyme proteins' abundance, whereas the P450_C17 abundance was increased. On days 27 to 28 of pregnancy, chemerin increased StAR and P450_C17 protein contents and decreased 3βHSD protein amounts. It was noted that the adipokine inhibited Erk1/2 and stimulated Akt phosphorylation. The obtained results indicate that chemerin affected P₄ and E₂ synthesis through the Erk1/2 and Akt signalling pathways.

Keywords: chemerin; endometrium; gestation; pig; signalling pathways; steroidogenesis.

Figure 1

The effect of chemerin on P₄ and E₂ secretion. The influence of chemerin (100, 200 ng/mL) on the secretion of progesterone (P₄; (a)) and oestradiol (E₂; (b)) by the in-vitro-incubated endometrial tissue explants collected from pigs on days 10 to 11, 12 to 13, 15 to 16, and 27 to 28 of pregnancy, and on days 10 to 11 of the oestrous cycle. The steroid hormone concentrations in culture media were evaluated using radioimmunoassay analysis. Data are presented as the mean ± standard error of the mean (n = 5). Bars with different letters are significantly different at p < 0.05. C—control; CH100—chemerin 100 ng/mL; CH200—chemerin 200 ng/mL.

Figure 2

The effect of chemerin on StAR and P450_SCC protein abundance. The influence of chemerin (100, 200 ng/mL) on the protein abundance of steroidogenic acute regulatory protein (StAR; (a)) and P450 side-chain cleavage enzyme (P450_SCC; (b)) in the in-vitro-incubated endometrial tissue explants collected from pigs on days 10 to 11, 12 to 13, 15 to 16, and 27 to 28 of pregnancy, and on days 10 to 11 of the oestrous cycle. The protein abundance of StAR and P450_SCC was evaluated using Western blot analysis. Upper panels—representative immunoblots, lower panels—densitometry analysis of target proteins’ relative content normalised with the actin protein. Data are presented as the mean ± standard error of the mean (n = 5). Bars with different letters are significantly different at p < 0.05. C—control; CH100—chemerin 100 ng/mL; CH200—chemerin 200 ng/mL.

Figure 3

The effect of chemerin on 3βHSD protein abundance. The influence of chemerin (100, 200 ng/mL) on the protein abundance of 3β-hydroxysteroid dehydrogenase (3βHSD) in the in-vitro-incubated endometrial tissue explants collected from pigs on days 10 to 11, 12 to 13, 15 to 16, and 27 to 28 of pregnancy, and on days 10 to 11 of the oestrous cycle. The protein abundance of 3βHSD was evaluated using Western blot analysis. Upper panels—representative immunoblots, lower panels—densitometry analysis of target proteins’ relative content normalised with the actin protein. Data are presented as the mean ± standard error of the mean (n = 5). Bars with different letters are significantly different at p < 0.05. C—control; CH100—chemerin 100 ng/mL; CH200—chemerin 200 ng/mL.

Figure 4

The effect of chemerin on P450_C17 and P450_AROM protein abundance. The influence of chemerin (100, 200 ng/mL) on the protein abundance of cytochrome P450_C17 (P450_C17; (a)) and cytochrome P450 aromatase (P450_AROM; (b)) in the in-vitro-incubated endometrial tissue explants collected from pigs on days 10 to 11, 12 to 13, 15 to 16, and 27 to 28 of pregnancy, and on days 10 to 11 of the oestrous cycle. The protein abundance of P450_C17 and P450_AROM was evaluated using Western blot analysis. Upper panels—representative immunoblots, lower panels—densitometry analysis of target proteins’ relative content normalised with the actin protein. Data are presented as the mean ± standard error of the mean (n = 5). Bars with different letters are significantly different at p < 0.05. C—control; CH100—chemerin 100 ng/mL; CH200—chemerin 200 ng/mL.

Figure 5

The effect of chemerin on the activation of Erk1/2 and Akt pathways. The influence of chemerin (200 ng/mL) on the activation of Erk1/2 (a) and Akt (b) signalling pathways in the in-vitro-incubated endometrial tissue explants collected from pigs on days 10 to 11 of the oestrous cycle. The total and phosphorylated Erk1/2 and Akt proteins’ abundances were evaluated using Western blot analysis. Upper panels—representative immunoblots, lower panels—densitometry analysis of phosphorylated target proteins’ relative content normalised with the total protein amounts. Data are presented as the mean ± standard error of the mean (n = 5). Bars with different letters are significantly different at p < 0.05.