Expression of visfatin in the ovarian follicles of prepubertal and mature gilts and in vitro effect of gonadotropins, insulin, steroids, and prostaglandins on visfatin levels

The role of asprosin in regulating ovarian granulosa- and theca-cell steroidogenesis: a review with comparisons to other adipokines

Adipose tissues produce a variety of biologically active compounds, including cytokines, growth factors and adipokines. Adipokines are important as they function as endocrine hormones that are related to various metabolic and reproductive diseases. The goal of this review was to summarise the role of asprosin, a recently discovered adipokine, and compare its role in ovarian steroidogenesis with that of other adipokines including adiponectin, leptin, resistin, apelin, visfatin, chemerin, irisin, and gremlin 1. The summary of concentrations of these adipokines in humans, rats and other animals will help researchers identify appropriate doses to test in future studies. Review of the literature indicated that asprosin increases androstenedione production in theca cells (Tc), and when cotreated with FSH increases oestradiol production in granulosa cells (Gc). In comparison, other adipokines (1) stimulate Gc oestradiol production but inhibit Tc androgen production (adiponectin), (2) inhibit Gc oestradiol production and Tc androstenedione production (leptin and chemerin), (3) inhibit Gc steroidogenesis with no effect on Tc (resistin), (4) inhibit Gc oestradiol production but stimulate Tc androgen production (gremlin 1), and (5) increase steroid secretion by Gc, with unknown effects on Tc steroidogenesis (apelin and visfatin). Irisin has direct effects on Gc but its precise role (inhibitory or stimulatory) may be species dependent and its effects on Tc will require additional research. Thus, most adipokines have direct effects (either positive or negative) on steroid production in ovarian cells, but how they all work together to create a cumulative effect or disease will require further research.

In vitro effect of visfatin on endocrine functions of the porcine corpus luteum

Previously, we demonstrated the expression of visfatin in porcine reproductive tissues and its effect on pituitary endocrinology. The objective of this study was to examine the visfatin effect on the secretion of steroid (P4, E2) and prostaglandin (PGE2, PGF2α), the mRNA and protein abundance of steroidogenic markers (STAR, CYP11A1, HSD3B, CYP19A1), prostaglandin receptors (PTGER2, PTGFR), insulin receptor (INSR), and activity of kinases (MAPK/ERK1/2, AKT, AMPK) in the porcine corpus luteum. We noted that the visfatin effect strongly depends on the phase of the estrous cycle: on days 2-3 and 14-16 it reduced P4, while on days 10-12 it stimulated P4. Visfatin increased secretion of E2 on days 2-3, PGE2 on days 2-3 and 10-12, reduced PGF2α release on days 14-16, as well as stimulated the expression of steroidogenic markers on days 10-12 of the estrous cycle. Moreover, visfatin elevated PTGER mRNA expression and decreased its protein level, while we noted the opposite changes for PTGFR. Additionally, visfatin activated ERK1/2, AKT, and AMPK, while reduced INSR phosphorylation. Interestingly, after inhibition of INSR and signalling pathways visfatin action was abolished. These findings suggest a regulatory role of visfatin in the porcine corpus luteum.

Visfatin impact on the proteome of porcine luteal cells during implantation

Visfatin (VIS) is a hormone belonging to the adipokines' group secreted mainly by the adipose tissue. VIS plays a crucial role in the control of energy homeostasis, inflammation, cell differentiation, and angiogenesis. VIS expression was confirmed in the hypothalamic-pituitary-gonadal (HPG) axis structures, as well as in the uterus, placenta, and conceptuses. We hypothesised that VIS may affect the abundance of proteins involved in the regulation of key processes occurring in the corpus luteum (CL) during the implantation process in pigs. In the present study, we performed the high-throughput proteomic analysis (liquid chromatography with tandem mass spectrometry, LC-MS/MS) to examine the in vitro influence of VIS (100 ng/mL) on differentially regulated proteins (DRPs) in the porcine luteal cells (LCs) on days 15-16 of pregnancy (implantation period). We have identified 511 DRPs, 276 of them were up-regulated, and 235 down-regulated in the presence of VIS. Revealed DRPs were assigned to 162 gene ontology terms. Western blot analysis of five chosen DRPs, ADAM metallopeptidase with thrombospondin type 1 motif 1 (ADAMTS1), lanosterol 14-α demethylase (CYP51A1), inhibin subunit beta A (INHBA), notch receptor 3 (NOTCH3), and prostaglandin E synthase 2 (mPGES2) confirmed the veracity and accuracy of LC-MS/MS method. We indicated that VIS modulates the expression of proteins connected with the regulation of lipogenesis and cholesterologenesis, and, in consequence, may be involved in the synthesis of steroid hormones, as well as prostaglandins' metabolism. Moreover, we revealed that VIS affects the abundance of protein associated with ovarian cell proliferation, differentiation, and apoptosis, as well as CL new vessel formation and tissue remodelling. Our results suggest important roles for VIS in the regulation of ovarian functions during the peri-implantation period.

Differential effect of visfatin inhibition on the testicular androgen and estrogen receptors expression in early pubertal mice

BACKGROUND

It is now well known that visfatin is expressed in the testis and ovary of various animals. Visfatin is known to regulate gonadal functions such as steroidogenesis, proliferation, and apoptosis in the ovary and testis of mice. Recently, we have shown that visfatin has an inhibitory role in the infantile mice testis. It has also been shown that visfatin stimulates testicular steroidogenesis in adult rats. However, the role of visfatin during puberty has not been investigated in relation to the above-mentioned process.

OBJECTIVE

The objective of the present study was to examine the effect of visfatin inhibition by FK866 from PND25 to PND35 (pre-pubertal to early pubertal) in male Swiss albino mice on steroidogenesis, proliferation, and apoptosis.

METHODS

Sixteen mice (25 days old) were divided into two groups, one group was given normal saline and the other group was administered with an inhibitor of visfatin (FK866) at the dose of 1.5 mg/kg by intraperitoneal injection for 10 days. Histopathological and immunohistochemical analysis, western blot analysis and hormonal assay were done.

RESULTS

Visfatin inhibition resulted in increased estrogen secretion, body weight, seminiferous tubule diameter, germinal epithelium height, and proliferation along with increased expression of BCl2, casapse3, ERs and aromatase expression in the mice testis. Visfatin inhibition down-regulated the testicular visfatin expression and also decreased abundance in the adipose tissues.

CONCLUSION

In conclusion, decreased AR expression and increased ERs expression by FK866, suggest that visfatin might have a stimulatory effect on AR signaling than ERs in the early pubertal stage of mice.

Adipokines in pregnancy

Reproductive success consists of a sequential events chronology, starting with the ovum fertilization, implantation of the embryo, placentation, and cellular processes like proliferation, apoptosis, angiogenesis, endocrinology, or metabolic changes, which taken together finally conduct the birth of healthy offspring. Currently, many factors are known that affect the regulation and proper maintenance of pregnancy in humans, domestic animals, or rodents. Among the determinants of reproductive success should be distinguished: the maternal microenvironment, genes, and proteins as well as numerous pregnancy hormones that regulate the most important processes and ensure organism homeostasis. It is well known that white adipose tissue, as the largest endocrine gland in our body, participates in the synthesis and secretion of numerous hormones belonging to the adipokine family, which also may regulate the course of pregnancy. Unfortunately, overweight and obesity lead to the expansion of adipose tissue in the body, and its excess in both women and animals contributes to changes in the synthesis and release of adipokines, which in turn translates into dramatic changes during pregnancy, including those taking place in the organ that is crucial for the proper progress of pregnancy, i.e. the placenta. In this chapter, we are summarizing the current knowledge about levels of adipokines and their role in the placenta, taking into account the physiological and pathological conditions of pregnancy, e.g. gestational diabetes mellitus, preeclampsia, or intrauterine growth restriction in humans, domestic animals, and rodents.

Integrated transcriptomic analysis on chicken ovary reveals CYP21A1 affects follicle granulosa cell development and steroid hormone synthesis

Egg production is an economically important trait in poultry breeding and production. Follicular development was regulated by several hormones released and genes expressed in the granulosa cells, impacting the egg production and fecundity of hens. However, the molecular functions of these candidate genes that modulate these processes remain largely unknown. In the present study, bioinformatics analyses were performed to identify the candidate genes related to egg production in the ovarian tissue of White Leghorns with high egg production and Beijing You chicken with low egg production during sexual maturity and peak laying periods. The ovarian granulosa cells were used to assess the function of CYP21A1 by transfecting with CYP21A1-specific small interfering RNAs (siRNAs) and overexpression plasmids. We identified 514 differentially expressed genes (|Log2(fold change) | >1, P <0.05) between the 2 chicken breeds in both laying periods. Among these genes, CYP21A1, which is involved in the steroid hormone biosynthesis pathway was consistently upregulated in White Leghorns. Weighted gene co-expression network analysis (WGCNA) further suggested that CYP21A1 was a hub gene, which could positively respond to treatment with follicle stimulation hormone (FSH), affecting egg production. The interference of CYP21A1 significantly inhibited cell proliferation and promoted cell apoptosis. Overexpression of CYP21A1 promotes cell proliferation and inhibits cell apoptosis. Furthermore, the interference with CYP21A1 significantly downregulated the expression of STAR, CYP11A1, HSD3B1, and FSHR and also decreased the synthesis of progesterone (P4) and estradiol (E2) in granulosa cells. Overexpression of CYP21A1 increased the synthesis of P4 and estradiol E2 and the expression of steroid hormone synthesis-related genes in granulosa cells. Our findings provide new evidence for the biological role of CYP21A1 on granulosa cell proliferation, apoptosis, and steroid hormone synthesis, which lays the theoretical basis for improving egg production.

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

Visfatin is a multifunctional protein which, besides the control of energy homeostasis, seems to be also involved in the regulation of female fertility through the influence on the endocrine hypothalamus-pituitary-gonadal axis, including the pituitary. The aim of this study was to investigate the expression of visfatin mRNA and protein in the anterior (AP) and posterior pituitary lobes of the pig during the oestrous cycle and early pregnancy. In AP, we also examined colocalisation of visfatin with pituitary tropic hormones. Moreover, we aimed to evaluate the in vitro effects of GnRH, FSH, LH, and insulin on visfatin protein concentration and secretion in AP cells during the cycle. The study showed that visfatin is present in all types of porcine pituitary endocrine cells and its expression is reliant on stage of the cycle or pregnancy. GnRH, FSH, LH and insulin stimulated visfatin secretion by AP cells on days 17 to 19 of the cycle, while on days 2 to 3 visfatin release was enhanced only by LH. Summarising, visfatin is locally produced in the pituitary in a way dependent on hormonal milieu typical for reproductive status of pigs. Further research is required to clarify the role of visfatin in the pituitary gland.