Expression of adiponectin receptors 1 and 2 in the ovary and concentration of plasma adiponectin during the oestrous cycle of the pig

Abstract

The aim of this study was to compare the expression levels of adiponectin receptor 1 and adiponectin receptor 2 mRNAs and proteins in porcine ovaries during four stages (days 2 to 3, 10 to 12, 14 to 16, 17 to 19) of the oestrous cycle and to measure adiponectin plasma concentrations during the same phases of the cycle. Higher mRNA expression of adiponectin receptor 1 was detected in porcine granulosa cells than in corpora lutea and theca cells (P < 0.01). In contrast, higher gene expression of adiponectin receptor 2 occurred in newly developed and mature corpora lutea (P < 0.01). The adiponectin receptor 1 protein content was the highest in corpora lutea isolated on days 2 to 3 of the cycle and was the lowest in theca interna cells (P < 0.01). The profile of adiponectin receptor 2 protein was similar to that of adiponectin receptor 1. Adiponectin plasma concentrations were significantly higher throughout the luteal phase than in the follicular phase (P < 0.01). In conclusion, the presence of adiponectin receptor 1 and adiponectin receptor 2 mRNAs and proteins in the porcine ovary suggests that adiponectin may directly affect ovarian functions through its own specific receptors. The expression of both receptors and adiponectin plasma concentration were dependent on hormonal status related to the stage of the cycle. Key words: Adiponectin receptors, adiponectin, pig, ovary, oestrous cycleAdiponectin is an adipose-secreted 244-amino-acid protein with 30 kDa molecular weight, which circulates in the blood in the form of a trimer (low molecular weight, LMW), a hexamer (middle molecular weight, MMW) or a multimer (high molecular weight, HMW) (Maeda et al., 1996). Adiponectin exerts its effect by binding to two distinct but structurally related 7-transmembrane receptors, adiponectin receptor 1 (AdipoR1) and adiponectin receptor 2 (AdipoR2).

Adiponectin expression in the porcine pituitary during the estrous cycle and its effect on LH and FSH secretion

“…Our earlier studies indicated that the AdipoR protein expression varied both during different phases of the estrous cycle as well as between AP and NP (19). Namely, the AripoR1 protein content was elevated in AP during the luteal phase, which seems to correlate with the plasma adiponectin levels reported by Maleszka et al (29). Interestingly, AdipoR2 protein was elevated on days 10 -12 in AP and on days 10 -12 and 17-19 in NP (19).…”

“…A study by Takemura et al (45) suggested that the increasing concentrations of estradiol in the human endometrium during the late proliferative phase (late follicular phase) may cause a decrease in adiponectin expression. Furthermore, Maleszka et al (28,29) indicated that both the level of adiponectin in the porcine plasma and adiponectin expression in the porcine ovary are lower during the follicular phase than in the luteal phase, which clearly indicates the influence of sex steroid hormones.…”

“…After the final wash, cells were incubated (24 h at 37°C, 5% CO 2 and 95% air) in 1 ml of McCoy's 5A medium containing bacitracin (2 ϫ 10 Ϫ5 M), without (control culture) or with the following agent's combination: 1) adiponectin (1 g/ml); 2) adiponectin (10 g/ml); 3) GnRH (100 ng/ml); 4) insulin (10 ng/ml); 5) GnRH (100 ng/ml) and insulin (10 ng/ml); 6) adiponectin (1 g/ml) and insulin (10 ng/ml); 7) adiponectin (10 g/ml) and insulin (10 ng/ml); 8) adiponectin (1 g/ml) and GnRH (100 ng/ml); 9) adiponectin (10 g/ml) and GnRH (100 ng/ml); 10) adiponectin (1 g/ml), GnRH (100 ng/ml), and insulin (10 ng/ml); or 11) adiponectin (10 g/ml), GnRH (100 ng/ml), and insulin (10 ng/ml). The doses of adiponectin, GnRH, and insulin were established based on Maleszka et al (28,29), Bogacka et al (7), and Gavin et al (12), respectively. Each in vitro experiment was performed on a different day using separate pools of AP cells.…”

“…A single paper demonstrates changes in AdipoR expression in both the anterior (AP) and posterior (NP) pituitary, related to the hormonal status (19). Similarly, the plasma level of adiponectin is differentiated dependent on the phase of the estrous cycle (29). Data describing an inverse relationship, namely an influence of the sex steroids level, typical for each phase of the estrous cycle, on the pituitary adiponectin system expression, is very limited.…”

The influence of adiponectin on the transcriptomic profile of porcine luteal cells

“…Cultures for each individual were performed in duplicate. The dose of adiponectin was equivalent to physiological concentration (Maleszka et al 2014b). The alamarBlue test (MP Biomedicals, USA) revealed that the treatment did not affect the viability of the cultured cells.…”