Plasma level and expression of visfatin in the porcine hypothalamus during the estrous cycle and early pregnancy

Abstract

Visfatin appears to be an energy sensor involved in the regulation of female fertility, which creates a hormonal link integrating the control of energy homeostasis and reproduction. This study evaluates the expression levels of visfatin gene and protein in selected areas of the porcine hypothalamus responsible for gonadotropin-releasing hormone synthesis: the mediobasal hypothalamus (MBH) and preoptic area (POA), and visfatin concentrations in the blood plasma. The tissue samples were harvested from gilts on days 2–3, 10–12, 14–16, and 17–19 of the estrous cycle, and on days 10–11, 12–13, 15–16, 27–28 of pregnancy. Visfatin was localized in the cytoplasm and nucleus of cells creating both studied hypothalamic structures. The study demonstrated that visfatin gene and protein expression in MBH and POA depends on hormonal status related to the phase of the estrous cycle or early pregnancy. Blood plasma concentrations of visfatin during the estrous cycle were higher on days 2–3 in relation to other studied phases of the cycle, while during early pregnancy, the highest visfatin contents were observed on days 12–13. This study demonstrated visfatin expression in the porcine hypothalamus and its dependence on the hormonal milieu related to the estrous cycle and early pregnancy.

Visfatin in the porcine pituitary gland: expression and regulation of secretion during the oestrous cycle and early pregnancy

“…Relationship between the visfatin expression and the phase of the oestrous cycle was also noted in other structures of the HPG axis and organs of the reproductive system. Changes in the expression of visfatin in the porcine hypothalamus during the oestrous cycle and early pregnancy were reported in our earlier study 17 . Visfatin gene and protein expression in the hypothalamic structures involved in GnRH synthesis, mediobasal hypothalamus and preoptic area, were dependent on hormonal status related to the phase of the oestrous cycle or early pregnancy and affected by steroid hormones.…”

“…RNA isolation, cDNA synthesis and qPCR reactions were performed as described previously 17 . In the case of qPCR, the conditions and characteristics of primers used in the study are detailed in Table 1 .…”

“…Western blot analysis was conducted similarly as described previously 17 . Protein isolation was performed using Tissue Protein Extraction Reagent (T-PER; Thermo Fisher Scientific, USA) according to the manufacturer's instructions.…”

“…no. MBS736963; MyBioSource, USA) as described previously 17 . The intra- and inter-assay coefficients of variability for performed analysis were 6.03% and 6.17%, respectively.…”

“…It seems that visfatin, apart from its direct effect on the reproductive system, may additionally influence the endocrine hypothalamus-pituitary-gonadal axis (HPG), including the pituitary, what has not been investigated so far. Visfatin is expressed in all structures of the HPG axis: in the hypothalamus of pigs 17 and mice 18 , in the pituitary gland of mice 19 and sheep 20 , as well as in the ovarian follicular cells of humans 12 , buffaloes 14 and pigs 21 . Its expression is hormonally controlled.…”