Expression of adiponectin receptors 1 (AdipoR1) and 2 (AdipoR2) in the porcine pituitary during the oestrous cycle

The mysterious association between adiponectin and endometriosis

Adiponectin is a pleiotropic cytokine predominantly derived from adipose tissue. In addition to its role in regulating energy metabolism, adiponectin may also be related to estrogen-dependent diseases, and many studies have confirmed its involvement in mediating diverse biological processes, including apoptosis, autophagy, inflammation, angiogenesis, and fibrosis, all of which are related to the pathogenesis of endometriosis. Although many researchers have reported low levels of adiponectin in patients with endometriosis and suggested that it may serve as a protective factor against the development of the disease. Therefore, the purpose of this review was to provide an up-to-date summary of the roles of adiponectin and its downstream cytokines and signaling pathways in the aforementioned biological processes. Further systematic studies on the molecular and cellular mechanisms of action of adiponectin may provide novel insights into the pathophysiology of endometriosis as well as potential therapeutic targets.

Adiponectin affects uterine steroidogenesis during early pregnancy and the oestrous cycle: An in vitro study

Reproduction in females is an energetically demanding process. We assumed that adiponectin (ADPN), known for its role in energy balance maintenance, is also engaged in the regulation of uterine steroidogenesis in the pig. We determined the impact of ADPN alone or in combination with insulin (INS) on testosterone (T), estrone (E₁) and estradiol (E₂) secretion by porcine endometrium and myometrium, uterine expression of CYP17A1 and CYP19A3 genes, and endometrial abundance of P450_C17 and P450_AROM proteins during the peri-implantation period and the oestrous cycle, using radioimmunoassay, qPCR, and Western Blot, respectively. During pregnancy, in the endometrial explants from days 10-11, ADPN decreased CYP17A1 gene expression, P450_C17 protein abundance and T secretion, whereas increased E₁ secretion. On days 12-13 of pregnancy, ADPN decreased CYP17A1 and CYP19A3 expression, P450_C17 and P450_AROM protein abundance and E₁ secretion, but stimulated T secretion. On days 15-16 of pregnancy, ADPN decreased P450_C17 protein accumulation but enhanced CYP19A3 expression and E₁ secretion. On days 27-28 of pregnancy, ADPN increased CYP17A1 and CYP19A3 mRNA content and T secretion in this tissue and decreased P450_C17 content. ADPN effect on myometrial explants was dependent on stage of gestation or oestrous cycle. Moreover, INS treatment modulated basal and ADPN-affected steroidogenic enzymes gene and protein expression and steroids secretion. The results obtained indicate that ADPN may affect processes required for successful implantation such as steroidogenesis. ADPN and INS were also shown to modulate each other action, which indicates that the proper course of uterine steroidogenesis may be dependent on both hormones' interaction.

A homozygous stop gain mutation in BOD1 gene in a Lebanese patient with syndromic intellectual disability

Intellectual disability (ID) is a neurodevelopmental disorder characterized by limitations in both intellectual and behavioral functioning. It can occur in non-syndromic and syndromic forms involving multiple organs. While the majority of genetic variants linked to ID are de novo, inherited variants are also detected in some forms. Here, we report a consanguineous Lebanese family presenting with an autosomal recessive syndromic ID characterized by neurodevelopmental delay, mild dysmorphic features, hearing impairment and endocrine dysfunction. Whole exome sequencing enabled the detection of the homozygous nonsense mutation in BOD1, p.R151X, in the proband. BOD1 is required for chromosomes biorientation during cell division. It also contributes to the regulation of cell survival and to the modulation of fatty acid metabolism. Another nonsense mutation in BOD1 was linked to ID in a consanguineous Iranian family. This is the second report of BOD1 mutations in humans and the first in a syndromic ID including gonadal dysfunction and high-frequency hearing impairment. Our findings confirm the involvement of BOD1 in cognitive functioning and expand the clinical spectrum of BOD1 deficiency.

Leucine regulates porcine muscle fiber type transformation via adiponectin signaling pathway

Leucine can promote slow-twitch muscle fibers formation, and this effect may be mediated by AMPK signaling pathway. In addition, adiponectin (AdipoQ) plays an important role in regulation of muscle fiber type transformation. AdipoQ is located in the upstream of AMPK and its secretion can be regulated by leucine. Therefore, the aim of this study was to explore whether leucine affects muscle fiber type transformation through AdipoQ signaling pathway. Our data showed that 4 mM leucine significantly increased protein expression levels of slow MyHC, Myoglobin, Troponin I-SS, AdipoQ, AdipoR1, phospho-AMPK (p-AMPK) and PGC-1α and mRNA expression levels of AMPKα2, PGC-1α, AdipoQ and AdipoR1, and significantly decreased fast MyHC protein expression. In addition, 4 mM leucine significantly increased the SDH activity while significantly decreased the LDH activity. However, knockdown of AdipoR1 expression by AdipoR1-siRNA abolished leucine-induced upregulation of protein expressions of slow MyHC, AdipoR1, p-AMPK, PGC-1α and NRF1, mRNA expressions of MyHC I, MyHC IIa, AdipoR1, AMPKα2 and PGC-1α, ATP5G, TFAM and NRF1, and mtDNA level, as well as downregulation of protein expression of fast MyHC and mRNA expression of MyHC IIb. Together, our data revealed that leucine promotes muscle fiber type transformation from fast-twitch to slow-twitch through AdipoQ signaling pathway.

Olanzapine-Induced Activation of Hypothalamic Astrocytes and Toll-Like Receptor-4 Signaling via Endoplasmic Reticulum Stress Were Related to Olanzapine-Induced Weight Gain

The antipsychotic drug olanzapine is associated with serious obesity side effects. Hypothalamic astrocytes and associated toll-like receptor-4 (TLR4) signaling play an essential role in obesity pathogenesis. This study investigated the effect of olanzapine on astrocytes and TLR4 signaling both in vitro and in the rat hypothalamus and their potential role in olanzapine-induced weight gain. We found that olanzapine treatment for 24 h dose-dependently increased cell viability, increased the protein expression of astrocyte markers including glial fibrillary acidic protein (GFAP) and S100 calcium binding protein B (S100B), and activated TLR4 signaling in vitro. In rats, 8- and 36-day olanzapine treatment caused weight gain accompanied by increased GFAP and S100B protein expression and activated TLR4 signaling in the hypothalamus. These effects still existed in pair-fed rats, suggesting that these effects were not secondary effects of olanzapine-induced hyperphagia. Moreover, treatment with an endoplasmic reticulum (ER) stress inhibitor, 4-phenylbutyrate, inhibited olanzapine-induced weight gain and ameliorated olanzapine-induced changes in hypothalamic GFAP, S100B, and TLR4 signaling. The expression of GFAP, S100B, and TLR4 correlated with food intake and weight gain. These findings suggested that olanzapine-induced increase in hypothalamic astrocytes and activation of TLR4 signaling were related to ER stress, and these effects may be related to olanzapine-induced obesity.

Sex- and season-dependent differences in the expression of adiponectin and adiponectin receptors (AdipoR1 and AdipoR2) in the hypothalamic-pituitary-adrenal axis of the Eurasian beaver (Castor fiber L.)

Adiponectin, a product of the Adipoq gene, is an adipocyte-derived protein hormone of the cytokine family and the most abundantly expressed adipokine. Adiponectin and its receptors AdipoR1 and AdipoR2 (collectively referred to as the adiponectin system) are widely expressed in the central nervous system and other tissues, which suggests that this hormone has pleiotropic effects. Adiponectin could also play a role in the modulation of the hypothalamic-pituitaryadrenal (HPA) hormonal regulatory axis. There is a general scarcity of data on the adiponectin system in wild animals where annual changes in reproductive activity are linked with fluctuations in the activity of the HPA axis. The Eurasian beaver (Castor fiber L.) could be an interesting and suitable model for investigating the above processes. We hypothesized that the expression of the adiponectin system in the tissues of the beaver HPA axis is sex- and season-dependent. The study was performed on adult animals harvested during three different stages of reproductive activity: April ('breeding'), July ('post-breeding') and November ('pre-breeding'). The expression of the adiponectin system was confirmed in all branches (mediobasal hypothalamus, pituitary, adrenal cortex) of the HPA axis in both sexes and during all periods of reproductive activity. The expression of Adipoq, AdipoR1 and AdipoR2 was generally dependent on sex and the period of the reproductive season. The expression of adiponectin system genes was particularly pronounced in the adrenal cortex. These findings suggest that the adiponectin system in the Eurasian beaver could link reproductive processes with stress responses and energy metabolism.

Expression and localization of adiponectin and its receptors (AdipoR1 and AdipoR2) in the hypothalamic-pituitary-ovarian axis of laying hens

Adiponectin is a hormone secreted by adipose tissue that is involved in the regulation of energy homeostasis and reproduction. In this study, the expression levels of adiponectin and its receptors in the hypothalamic-pituitary-ovarian (HPO) axis of laying hens were investigated using quantitative real-time PCR (qRT-PCR) and Western blotting, and the localization of these proteins was explored using immunohistochemistry. The morphological relationships between adiponectin receptors and gonadotropin-releasing hormone (GnRH) neurons were analyzed using double immunofluorescence labeling. The results showed that adiponectin mRNA and protein were widely expressed in all tissues involved in the HPO axis in laying hens, with especially high expression in the hypothalamus. Both AdipoR1 and AdipoR2 were more highly expressed in the pituitary than in other tissues and exhibited similar mRNA and protein expression patterns. The immunohistochemistry results showed that adiponectin and AdipoR2 were localized in the major hypothalamic nuclei that regulate food intake and energy balance (i.e., the lateral hypothalamic area (LHA), infundibular nucleus (IN), dorsomedial nucleus (DMN), and paraventricular nucleus (PVN)). Immunostaining revealed that adiponectin and its receptors were also localized in the cytoplasm of cells in the adenohypophysis. In the ovaries, adiponectin was localized in the granulosa layer, in the theca externa of follicles and in basal cells, while AdipoR1 and AdipoR2 were localized in basal cells. In the double immunofluorescence labeling experiment, AdipoR1 and AdipoR2 were localized in GnRH neurons in the IN and DMN. These results suggest that adiponectin and its receptors may play major roles in the endocrine network, which integrates energy balance and reproduction.

Relative abundance of chemerin mRNA transcript and protein in pituitaries of pigs during the estrous cycle and early pregnancy and associations with LH and FSH secretion during the estrous cycle

Adipokines such as chemerin affect metabolic status and reproductive function in many species. The hypothesis in the present study was that there were chemerin mRNA transcript and protein in the pituitary of pigs and that relative abundances fluctuate during the estrous cycle and early pregnancy. Chemerin is thought to modulate luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretion during the estrous cycle. Changes in the relative abundance of chemerin mRNA transcript and protein in anterior (AP) and posterior (PP) pituitaries of pigs were investigated, for the first time in the present study, during four phases of the estrous cycle and four periods of early pregnancy. Chemerin protein was localized in gonadotrophs, thyrotrophs and somatotrophs during the estrous cycle and early gestation. Chemerin treatments affected both basal, GnRH- and/or insulin-induced LH and FSH production, with there being variations with phase of the estrous cycle when tissues were collected. These findings indicate chemerin may be produced locally in the pituitary and may affect female reproductive function by controlling the release of LH and FSH from AP cells.

Modulation of adiponectin system expression in the porcine uterus during early pregnancy by prostaglandin E2 and F2α

Studies have demonstrated that adiponectin could be a link between reproductive functions and energy metabolism in animals. The aim of the present study was to investigate the effects of prostaglandin (PG) E₂ and PGF_2α (10, 50, 100, 250 and 500ngmL^-1) on the expression and secretion of adiponectin and its receptor genes and proteins by cultured in vitro porcine endometrial and myometrial tissues on Days 10-28 of pregnancy and Days 10-11 of the oestrous cycle. The gene expression was analysed using the real-time PCR method. Adiponectin protein secretion was determined by ELISA, whereas the receptors proteins content was defined using Western Blot analysis. Both PGE₂ and PGF_2α modulated the expression of adiponectin system genes and proteins in the uterus during early pregnancy. PGE₂ and PGF_2α had similar effects on the adiponectin system, which differed between the stages of gestation and between pregnancy and the oestrous cycle. On Days 10-11 of gestation, PGE₂ and PGF_2α generally increased adiponectin secretion by endometrial and myometrial tissues. Both PGs decreased levels of endometrial adiponectin receptor type 1 (AdipoR1), whereas only PGF_2α decreased myometrial levels of AdipoR1. Both PGs increased myometrial adiponectin receptor type 2 (AdipoR2) levels. On Days 12-13 of gestation, PGE₂ decreased AdipoR1 concentrations in both tissues and AdipoR2 levels in the endometrium. PGF_2α decreased myometrial concentrations of both receptors. On Days 15-16 of gestation, both PGE₂ and PGF_2α increased concentrations of AdipoR1 and AdipoR2 in the endometrium and myometrium. PGE₂ stimulated the secretion of adiponectin in the endometrium, but not in the myometrium. On Days 27-28 of pregnancy, both PGE₂ and PGF_2α inhibited the expression of AdipoR1 and AdipoR2 in endometrial and myometrial tissues and decreased the secretion of endometrial adiponectin. Both PGE₂ and PGF_2α had tissue-specific and dose-dependent effects on the adiponectin system.

Adiponectin: A New Regulator of Female Reproductive System

Adiponectin is the hormone that belongs to the group of adipokines, chemical agents mainly derived from the white adipose tissue. The hormone plays pleiotropic roles in the organism, but the most important function of adiponectin is the control of energy metabolism. The presence of adiponectin and its receptors in the structures responsible for the regulation of female reproductive functions, such as hypothalamic-pituitary-gonadal (HPG) axis, indicates that adiponectin may be involved in the female fertility regulation. The growing body of evidence suggests also that adiponectin action is dependent on the actual and hormonal status of the animal. Present study presents the current knowledge about the presence and role of adiponectin system (adiponectin and its receptors: AdipoR1 and AdipoR2) in the ovaries, oviduct, and uterus, as well as in the hypothalamus and pituitary, the higher branches of HPG axis, involved in the female fertility regulation.

Adiponectin, orexin A and orexin B concentrations in the serum and uterine luminal fluid during early pregnancy of pigs

Adiponectin is the most abundant adipose-released protein that circulates in human plasma at high concentrations. The neuropeptides orexin A (OXA, hypocretin-1) and orexin B (OXB, hypocretin-2) are derived from a common precursor peptide, prepro-orexin and are produced mainly by neurons located in the lateral hypothalamus. It has been demonstrated that the peptides such as adiponectin and orexins have an important role in the regulation of energy metabolism and neuroendocrine functions. These hormones appear to be implicated in both normal and disturbed pregnancy. The objectives of this study were to determine adiponectin and orexin concentrations in the plasma and uterine luminal fluid (ULF) of pigs during early gestation and to explore the relationships between hormone concentrations and stages of pregnancy. The greatest plasma concentrations of adiponectin were observed on days 15-16 and 27-28 of pregnancy, and the least concentrations were on days 30-32 of gestation and on days 10-11 of the oestrous cycle. In ULF, adiponectin concentrations were greater on days 15-16 of pregnancy and on days 10-11 of the oestrous cycle than on days 10-11 and days 12-13 of pregnancy. The greatest OXA concentrations in the blood plasma were noted on days 10-16 of gestation, and the least OXA concentrations were on days 27-32 of pregnancy and on days 10-11 of the oestrous cycle. Orexin A concentrations in ULF were greater on days 10-11 of the cycle than throughout pregnancy. Serum OXB concentrations were greatest on days 10-11 and 30-32 of pregnancy, and least on days 12-28 of gestation. The greatest OXB concentrations in ULF were on days 10-13 of gestation, and the least OXB concentrations were on days 15-16 of pregnancy. This is first study to demonstrate the presence of adiponectin and orexins in the serum and ULF during early pregnancy of pigs as well as the relationships between adiponectin and orexin concentrations and the stage of pregnancy. The fluctuations in adiponectin and orexin concentrations in the plasma and ULF suggest that the hormones present in ULF are mostly of local origin and that these hormones participate in the processes that accompany early pregnancy.

The effect of estrone and estradiol on the expression of the adiponectin system in the porcine uterus during early pregnancy

Adiponectin is secreted by the white adipose tissue and is one of the most important hormones that regulate metabolic homeostasis. The expression of adiponectin and adiponectin receptor genes and proteins in reproductive organs, such as the testes, ovaries, and uterus, suggests that adiponectin is also involved in the regulation of reproductive functions. Changes in the expression of adiponectin and adiponectin receptor genes and proteins in the porcine uterus during the estrous cycle and early pregnancy imply that adiponectin activity may be controlled by the local hormonal milieu. Estrone (E1) and estradiol (E2) are the key steroid hormones that regulate reproductive functions, including the early recognition of pregnancy and implantation. We hypothesize that E1 and E2 may regulate the expression of the adiponectin system in a pregnant uterus. The aim of this study was to investigate the influence of E1 and E2 on the expression of adiponectin and its receptor genes and proteins by porcine endometrial and myometrial explants harvested from gilts (n = 5 per group) 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 estrous cycle. The expression of adiponectin and AdipoRs genes was examined with the real-time polymerase chain reaction, adiponectin secretion was evaluated with the ELISA method, and the expression of receptor proteins was determined using the Western blotting method. The results revealed that both E1 and E2 significantly influenced the expression of the adiponectin gene, hormone secretion in vitro, and the expression of AdipoRs genes and proteins. The influence of E1 and E2 on the expression of the adiponectin system varied in the early gestation, during the estrous cycle and between different stages of gestation. The examined steroids had a tissue-specific and a dose-dependent effect. This is the first ever study to describe the modulatory effect of E1 and E2 on the expression of the adiponectin system in the porcine uterus during early gestation.

Monomeric adiponectin modulates nitric oxide release and calcium movements in porcine aortic endothelial cells in normal/high glucose conditions

AIMS

Perivascular adipose tissue can be involved in the process of cardiovascular pathology through the release of adipokines, namely adiponectins. Monomeric adiponectin has been shown to increase coronary blood flow in anesthetized pigs through increased nitric oxide (NO) release and the involvement of adiponectin receptor 1 (AdipoR1). The present study was therefore planned to examine the effects of monomeric adiponectin on NO release and Ca(2+) transients in porcine aortic endothelial cells (PAEs) in normal/high glucose conditions and the related mechanisms.

MAIN METHODS

PAEs were treated with monomeric adiponectin alone or in the presence of intracellular kinases blocker, AdipoR1 and Ca(2+)-ATPase pump inhibitors. The role of Na(+)/Ca(2+) exchanger was examined in experiments performed in zero Na(+) medium. NO release and intracellular Ca(2+) were measured through specific probes.

KEY FINDINGS

In PAE cultured in normal glucose conditions, monomeric adiponectin elevated NO production and [Ca(2+)]c. Similar effects were observed in high glucose conditions, although the response was lower and not transient. The Ca(2+) mobilized by monomeric adiponectin originated from an intracellular pool thapsigargin- and ATP-sensitive and from the extracellular space. Moreover, the effects of monomeric adiponectin were prevented by kinase blockers and AdipoR1 inhibitor. Finally, in normal glucose condition, a role for Na(+)/Ca(2+) exchanger and Ca(2+)-ATPase pump in restoring Ca(2+) was found.

SIGNIFICANCE

Our results add new information about the control of endothelial function elicited by monomeric adiponectin, which would be achieved by modulation of NO release and Ca(2+) transients. A signalling related to Akt, ERK1/2 and p38MAPK downstream AdipoR1 would be involved.

Impact of Food Restriction on the Expression of the Adiponectin System and Genes in the Hypothalamic-Pituitary-Ovarian Axis of Pre-Pubertal Ewes

Adiponectin, a cytokine secreted typically by adipocytes, has been implicated as a molecular switch between female reproduction and energy balance. The present study was undertaken to investigate the expression of adiponectin system and patterns of genes in the hypothalamic-pituitary-ovary (HPO) axis of food-restricted pre-pubertal ewes. Eighteen 2-month-old female ewes were assigned to 3 groups after a pre-feeding ad libitum for 10 days (six in each group): the control group (C), the low-food-restricted group (LR) and the high-food-restricted group (HR), which were fed with 100%, 70% and 50% of ad libitum food intake, respectively. The hypothalamus, pituitary, ovary and serum were collected after food restriction for 2 months. Results by ELISA showed that food restriction increased serum adiponectin concentrations. Quantitative real-time PCR showed that the gene transcriptions for adiponectin receptor 1 (AdipoR1) and 2 (AdipoR2) were enhanced in the hypothalamic-pituitary-ovarian (HPO) axis, while KISS-1/GPR-54 and gonadotropin-releasing hormone (GnRH) in the hypothalamus and luteinizing hormone β-subunit (LHβ) and follicle-stimulating hormone β-subunit (FSHβ) in the pituitary were reduced after food restriction. Immunohistochemistry results demonstrated that AdipoR1 localized in the oocytes of follicles in the ovary. These results suggest that the alterations in the expression of adiponectin and its receptors in response to food restriction might negatively influence the HPO axis.

The Deep Correlation between Energy Metabolism and Reproduction: A View on the Effects of Nutrition for Women Fertility

In female mammals, mechanisms have been developed, throughout evolution, to integrate environmental, nutritional and hormonal cues in order to guarantee reproduction in favorable energetic conditions and to inhibit it in case of food scarcity. This metabolic strategy could be an advantage in nutritionally poor environments, but nowadays is affecting women's health. The unlimited availability of nutrients, in association with reduced energy expenditure, leads to alterations in many metabolic pathways and to impairments in the finely tuned inter-relation between energy metabolism and reproduction, thereby affecting female fertility. Many energetic states could influence female reproductive health being under- and over-weight, obesity and strenuous physical activity are all conditions that alter the profiles of specific hormones, such as insulin and adipokines, thus impairing women fertility. Furthermore, specific classes of nutrients might affect female fertility by acting on particular signaling pathways. Dietary fatty acids, carbohydrates, proteins and food-associated components (such as endocrine disruptors) have per se physiological activities and their unbalanced intake, both in quantitative and qualitative terms, might impair metabolic homeostasis and fertility in premenopausal women. Even though we are far from identifying a "fertility diet", lifestyle and dietary interventions might represent a promising and invaluable strategy to manage infertility in premenopausal women.

In vitro interaction between resistin and peroxisome proliferator-activated receptor γ in porcine ovarian follicles

In the present study, using real-time polymerase chain reaction and immunoblotting methods, we quantified the expression of peroxisome proliferator-activated receptor (PPAR) γ, PPARα and PPARβ in different sized ovarian follicles (small (SF), medium (MF) and large (LF) follicles) in prepubertal and adult pigs. In prepubertal pigs, PPARγ and PPARα expression was highest in LF; however, PPARβ expression did not differ among SF, MF and LF. In mature pigs, only protein expression of PPARγ and PPARα increased during ovarian follicle development. Following identification of very high levels of PPARγ expression in LF in prepubertal and adult pigs, using in vitro culture of ovarian follicles, we determined the effect of resistin at 0.1, 1 and 10 ng mL–1 on PPARγ mRNA and protein expression and the effect of rosiglitazone at 25 and 50 µM (a PPARγ agonist) on resistin mRNA and protein expression. Resistin increased PPARγ expression in ovarian follicles in both prepubertal and adult pigs, whereas rosiglitazone had an inhibitory effect on resistin expression. The role of PPARγ in regulating the effects of resistin on ovarian steroidogenesis was investigated using GW9662 (a PPARγ antagonist at dose of 1 μM). In these studies, GW9662 reversed the effect of resistin on steroid hormone secretion. The data suggest that there is local cooperation between resistin and PPARγ expression in the porcine ovary. Resistin significantly increased the expression of PPARγ, whereas PPARγ decreased resistin expression; thus, PPARγ is a new key regulator of resistin expression and function.

Molecular cloning and expression analysis of adiponectin and its receptors (AdipoR1 and AdipoR2) in the hypothalamus of the Huoyan goose during different stages of the egg-laying cycle

BACKGROUND

Adiponectin and its receptors (AdipoR1 and AdipoR2) are novel endocrine systems that act at various levels to regulate metabolic homeostasis and reproductive processes. We cloned and characterized the cDNA of adiponectin and its receptors from the hypothalamus of the Huoyan goose to reveal the influence of these factors on the process of goose egg-laying. We also determined the mRNA and protein expression profiles during different stages of the egg-laying cycle.

METHODS

Hypothalamus tissues were obtained from 36 Huoyan geese in the pre-laying, early-laying, peak-laying, and ceased periods. The cDNA sequences of goose adiponectin and its receptors (AdipoR1 and AdipoR2) were cloned and characterized using the 5'-RACE and 3'-RACE methods. Multiple alignments and phylogenetic analyses of the deduced amino acid sequence were conducted using bioinformatics tools. The expression profiles of mRNA and protein in the hypothalamus during the pre-laying, early-laying, peak-laying and ceased periods were examined using real-time PCR (qRT-PCR) and Western blotting techniques.

RESULTS

The cDNA of adiponectin, AdipoR1 and AdipoR2 consisted of 738, 1131 and 1161 bp open reading frame encoding 245, 376 and 386 amino acids, respectively. The deduced amino acid sequence of goose adiponectin, as well as AdipoR1 and AdipoR2 showed a closer genetic relationship to the avian species than to other mammal species. The expression level of adiponectin mRNA and protein increased from the pre-laying period to the peak-laying period, reached its peak in the peak-laying period, and then decreased during the ceased period. Conversely, the expression levels of AdipoR1 and AdipoR2 mRNA and protein decreased in the early-laying period, peak-laying period, and ceased period compared with the pre-laying period.

CONCLUSIONS

This study is the first to obtain full-length cDNA sequences of goose adiponectin and the genes of its receptors from the hypothalamus, and demonstrate that the egg-laying cycle affects the expression of the goose adiponectin system. Our results suggest the potential role of adiponectin as a key neuromodulator of reproductive functions.

Resistin is a survival factor for porcine ovarian follicular cells

Previously, we demonstrated the expression of resistin in the porcine ovary, the regulation of its expression and its direct effect on ovarian steroidogenesis. The objective of this study was to examine the effect of resistin on cell proliferation and apoptosis in a co-culture model of porcine granulosa and theca cells. First, we analysed the effect of resistin at 1 and 10  ng/ml alone or in combination with FSH- and IGF1 on ovarian cell proliferation with an alamarBlue assay and protein expression of cyclins A and B using western blot. Next, the mRNA and protein expression of selected pro-apoptotic and pro-survival regulators of cell apoptosis, caspase-9, -8 and -3 activity and DNA fragmentation using real time PCR, western blot, fluorescent assay and an ELISA kit, respectively, were analysed after resistin treatment. Furthermore, we determined the effect of resistin on the protein expression of ERK1/2, Stat and Akt kinase. Using specific inhibitors of these kinases, we also checked caspase-3 activity and protein expression. We found that resistin, at both doses, has no effect on cell proliferation. The results showed that resistin decreased pro-apoptotic genes, which was confirmed on protein expression of selected factors. We demonstrate an inhibitory effect of resistin on caspase activity and DNA fragmentation. Finally, resistin stimulated phosphorylation of the ERK1/2, Stat and Akt and kinases inhibitors reversed resistin action on caspase-3 activity and protein expression to control. All of these results showed that resistin has an inhibitory effect on porcine ovarian cell apoptosis by activation of the MAPK/ERK, JAK/Stat and Akt/PI3 kinase signalling pathways.

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

Female reproductive success is closely associated with nutritional status and energy balance. In this context, adiponectin appears to be a key hormone connecting reproductive system function and metabolism regulation. It is hypothesized that adiponectin expression in the pituitary depends on the phase of the estrous cycle. The effect of adiponectin on luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretion is also postulated. Changes in the adiponectin gene and protein expression in the porcine anterior (AP) and posterior (NP) pituitaries as well as the effect of in vitro administration of adiponectin on basal and gonadotropin-releasing hormone (GnRH)- and/or insulin-stimulated LH and FSH secretion were investigated on days 2-3, 10-12, 14-16, and 17-19 of the estrous cycle. Adiponectin gene was more pronounced on days 2-3 in AP but on days 10-12 in NP. Protein concentration in AP was the highest on days 10-12 and in NP on days 10-12 and 17-19 of the cycle. In vitro, adiponectin did not affect basal LH secretion but increased FSH release by AP cells. Adiponectin administration affected GnRH- and/or insulin-induced LH and FSH output in a manner dependent on the phase of the estrous cycle. In this study we indicated for the first time adiponectin expression in the porcine AP and NP that was dependent on the phase of the estrous cycle. In vitro studies indicated that adiponectin may affect gonadotropin secretion. The above suggests that the studied adipokine may influence female reproductive functions via its effect on LH and FSH secretion by gonadotrophs, but the cellular mechanism of its action remains unknown.

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

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.

Expression of adiponectin and adiponectin receptors 1 and 2 in the porcine uterus, conceptus, and trophoblast during early pregnancy

Adiponectin, one of the several adipocytokines secreted mainly by the adipose tissue, plays an important role in regulating energy homeostasis and controls female fertility. Female reproductive functions are closely associated with nutritional status, and adiponectin seems to be an important factor linking the regulation of metabolic homeostasis with reproductive processes. The biological activity of adiponectin is mediated by two distinct receptors, adiponectin receptor 1 (AdipoR1) and adiponectin receptor 2 (AdipoR2). The objective of this study was to determine the presence of and changes in the gene and protein expression pattern of adiponectin and its receptors in the porcine uterus during early pregnancy and on Days 10 to 11 of the estrous cycle and in the conceptus and trophoblast. The highest level of adiponectin transcript was observed on Days 15 to 16 of gestation, Days 10 to 11 of the cycle in the endometrium, and Days 15 to 16 of gestation in the myometrium. The highest expression of AdipoR1 and AdipoR2 genes was detected on Days 10 to 11 of gestation in the endometrium, and Days 12 to 13 in the myometrium. The highest content of adiponectin protein was noted on Days 12 to 13 and 30 to 32 of gestation in the endometrium and Days 10 to 11 of the cycle in the myometrium. The expression of adiponectin protein was higher on Days 27 to 28 and 30 to 32 in the conceptuses. AdipoR1 protein content in the myometrium was highest on Days 12 to 13 and 30 to 32. In contrast, in the endometrium, it was more constant. The highest content of AdipoR2 protein was detected on Days 15 to 16 and 30 to 32 of gestation, Days 10 to 11 of the cycle in the endometrium, and Days 10 to 11 of gestation in the myometrium. In the conceptuses, the highest AdipoR1 protein content was observed on Days 15 to 16, and the highest AdipoR2 protein expression was determined on Days 15 to 16 and 27 to 28. In the trophoblasts, AdipoR1 protein content was higher on Days 27 to 28 than on Days 30 to 32, whereas the expression of AdipoR2 was higher on Days 30 to 32. This study demonstrated the presence of adiponectin and its receptors in the uteri, conceptuses, and trophoblasts of pregnant pigs and that the local adiponectin system is dependent on the stage of pregnancy.

Effect of monomeric adiponectin on cardiac function and perfusion in anesthetized pig

Adiponectin, the most abundant adipokine released by adipose tissue, appears to play an important role in the regulation of vascular endothelial and cardiac function. To date, however, the physiological effects of human monomeric adiponectin on the coronary vasculature and myocardial systo-diastolic function, as well as on parasympathetic/sympathetic involvement and nitric oxide (NO) release, have not yet been investigated. Thus, we planned to determine the primary in vivo effects of human monomeric adiponectin on coronary blood flow and cardiac contractility/relaxation and the related role of autonomic nervous system, adiponectin receptors, and NO. In 30 anesthetized pigs, human monomeric adiponectin was infused into the left anterior descending coronary artery at constant heart rate and arterial blood pressure, and the effects on coronary blood flow, left ventricular systo-diastolic function, myocardial oxygen metabolism, and NO release were examined. The mechanisms of the observed hemodynamic responses were also analyzed by repeating the highest dose of human monomeric adiponectin infusion after autonomic nervous system and NO blockade, and after specific adiponectin 1 receptor antagonist administration. Intracoronary human monomeric adiponectin caused dose-related increases of coronary blood flow and cardiac function. Those effects were accompanied by increased coronary NO release and coronary adiponectin levels. Moreover, the vascular effects of the peptide were prevented by blockade of β2-adrenoceptors and NO synthase, whereas all effects of human monomeric adiponectin were prevented by adiponectin 1 receptor inhibitor. In conclusion, human monomeric adiponectin primarily increased coronary blood flow and cardiac systo-diastolic function through the involvement of specific receptors, β2-adrenoceptors, and NO release.

Adipose tissue as an endocrine organ

Obesity is one of the most important health challenges faced by developed countries and is increasingly affecting adolescents and children. Obesity is also a considerable risk factor for the development of numerous other chronic diseases, such as insulin resistance, type 2 diabetes, heart disease and nonalcoholic fatty liver disease. The epidemic proportions of obesity and its numerous comorbidities are bringing into focus the highly complex and metabolically active adipose tissue. Adipose tissue is increasingly being considered as a functional endocrine organ. This article discusses the endocrine effects of adipose tissue during obesity and the systemic impact of this signaling.