GPR30 mediates estrone, estriol, and estradiol to suppress gonadotropin-releasing hormone-induced luteinizing hormone secretion in the anterior pituitary of heifers

Mechanism difference of ginseng medicines with different natures on hyperthyroidism

ETHNOPHARMACOLOGICAL RELEVANCE

Medicinal nature is a unique index in traditional Chinese medicine (TCM) to measure the efficacy of Chinese medicines. Hyperthyroidism, qi-Yin deficiency syndrome in TCM was regarded as the classic heat syndrome category in Chinese medicine. Moreover, it is extensively employed to evaluate the medicinal nature of herbs within the framework of the 'hot/cold' nature theory. Ginseng, red and black ginseng (GS, RG, and BG, respectively), and ginseng leaves (GL) are qi-tonifying herbs with different medicinal natures and were just right used to examine the underlying mechanisms between the nature of ginseng medicines and their tonifying effect.

AIM OF THE STUDY

To examine the different mechanisms between different natures of ginseng medicines and their qi-tonifying action by comparison of their effects on hyperthyroidism and elucidate the nature of BG.

MATERIALS AND METHODS

The hyperthyroidism model was induced through the oral administration of Euthyrox. Steroids belonging to hypothalamus pituitary adrenal (HPA) and hypothalamic pituitary gonadal (HPG) axes were determined with an ultra-performance liquid chromatography-triple quadrupole tandem mass spectrometry (UPLC-QqQ-MS/MS) method. Furthermore, the biochemical indexes associated with energy metabolism, including the serum cyclic nucleotide system and phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt) signaling pathways were examined. Additionally, the gut microbiota was subjected to 16 S rDNA sequencing, followed by gas chromatography-mass spectrometry (GC-MS) analysis of short-chain fatty acids (SCFAs).

RESULTS

GS, RG, and BG could treat hyperthyroidism rats by regulating the hypothalamus pituitary thyroid (HPT) axis. The RG also had a strong regulatory effect on the HPA and HPG axis. The BG has a regulatory effect on the HPG axis. GL had a strong regulatory effect on HPA, HPG, and HPT axes. GS had the ability to regulate Firmicutes/Bacteroides of the intestinal flora, and GS, RG, and BG ameliorated the decrease of SCFAs induced by hyperthyroidism. According to PCA, BG is similar to GS, indicating a mild-warm nature.

CONCLUSION

The nature of BG was attributable to mild-warm and the GL with cold nature is best for the treatment of hyperthyroidism based on PCA analysis with all the bio-indices. In addition, the mechanism study indicated that the qi-tonifying effects of ginseng medicines are involved in HPT, HPA, and HPG axes to alleviate hyperthyroidism. In addition, the primary indexes reflected different natures of ginseng medicines are cyclic adenosine monophosphate (cAMP)/cyclic guanosine monophosphate (cGMP), AchE, and substance metabolism associated with Na+-K+-ATPase and PI3K/AKT signaling pathways, which are potential biomarkers for evaluation on the natures of qi-tonifying medicines.

Exploring genome-wide differentiation and signatures of selection in Italian and North American Holstein populations

Among Italian dairy cattle, the Holstein is the most reared breed for the production of Parmigiano Reggiano protected designation of origin cheese, which represents one of the most renowned products in the entire Italian dairy industry. In this work, we used a medium-density genome-wide data set consisting of 79,464 imputed SNPs to study the genetic structure of Italian Holstein breed, including the population reared in the area of Parmigiano Reggiano cheese production, and assessing its distinctiveness from the North American population. Multidimensional scaling and ADMIXTURE approaches were used to explore the genetic structure among populations. We also investigated putative genomic regions under selection among these 3 populations by combining 4 different statistical methods based either on allele frequencies (single marker and window-based) or extended haplotype homozygosity (EHH; standardized log-ratio of integrated EHH and cross-population EHH). The genetic structure results allowed us to clearly distinguish the 3 Holstein populations; however, the most remarkable difference was observed between Italian and North American stock. Selection signature analyses identified several significant SNPs falling within or closer to genes with known roles in several traits such as milk quality, resistance to disease, and fertility. In particular, a total of 22 genes related to milk production have been identified using the 2 allele frequency approaches. Among these, a convergent signal has been found in the VPS8 gene which resulted to be involved in milk traits, whereas other genes (CYP7B1, KSR2, C4A, LIPE, DCDC1, GPR20, and ST3GAL1) resulted to be associated with quantitative trait loci related to milk yield and composition in terms of fat and protein percentage. In contrast, a total of 7 genomic regions were identified combining the results of standardized log-ratio of integrated EHH and cross-population EHH. In these regions candidate genes for milk traits were also identified. Moreover, this was also confirmed by the enrichment analyses in which we found that the majority of the significantly enriched quantitative trait loci were linked to milk traits, whereas the gene ontology and pathway enrichment analysis pointed to molecular functions and biological processes involved in AA transmembrane transport and methane metabolism pathway. This study provides information on the genetic structure of the examined populations, showing that they are distinguishable from each other. Furthermore, the selection signature analyses can be considered as a starting point for future studies in the identification of causal mutations and consequent implementation of more practical application.

Ethanolamine plasmalogens derived from whale brain stimulate both follicle-stimulating hormone and luteinizing hormone secretion by bovine gonadotrophs

Ethanolamine plasmalogens (EPls) are the only known ligands of a novel receptor, G protein-coupled receptor 61, and bovine brain EPls stimulate follicle-stimulating hormone (FSH) but not luteinizing hormone (LH), secreted by bovine gonadotrophs. We hypothesized that the brain EPls of whales (Balaenoptera edeni), another Cetartiodactyla with at least twice the lifespan of bovines, could stimulate FSH secretion by gonadotrophs. To test this hypothesis, bovine gonadotrophs (from approximately 2-year-old Japanese Black heifers) were cultured for 3.5 days and treated with increasing concentrations of brain EP1s from whales (approximately 22 years old). FSH and LH secretion was stimulated by all tested concentrations of whale EPls (p < 0.05). To clarify the important differences between bovine and whale EPls, we utilized two-dimensional liquid chromatography-mass spectrometry, which revealed 35 peaks. Among them, we observed significant differences between 12 EPl molecular species. Additionally, we identified differentially expressed genes for enzymes involved in EPl synthesis or degradation in the hypothalamus of young heifers and old cows (approximately 10 years old) as compared to whales (approximately 28 years old) via deep sequencing of the transcriptome. We conclude that whale brains contain unique EPls that stimulate both FSH and LH secretion by bovine gonadotrophs.

Ethanolamine plasmalogens derived from scallops stimulate both follicle-stimulating hormone and luteinizing hormone secretion by bovine gonadotrophs

Brain ethanolamine plasmalogens (EPls) are the only known ligands of G-protein-coupled receptor 61, a novel receptor that stimulates follicle-stimulating hormone (FSH), but not luteinizing hormone (LH), secretion by bovine gonadotrophs. We hypothesized that the recently developed neuroprotective EPls extracted from scallop (Pecten yessoensis) (scallop EPls) could stimulate FSH secretion by gonadotrophs. To test this hypothesis, bovine gonadotrophs were cultured for 3.5 days and treated with increasing concentrations of scallop EPls. FSH secretion was stimulated by all tested concentrations of scallop EPls (P < 0.05). Surprisingly, LH secretion was stimulated by both 0.5 (P < 0.05) and 5 (P < 0.01) ng/mL of scallop EPls. To clarify the important differences between bovine brain and scallop EPls, we utilized two-dimensional liquid chromatography–mass spectrometry, which revealed 44 peaks, including 10 large peaks. Among them, eight were scallop-specific EPl molecular species, occupying approximately 58% of the total area percentage of scallop EPls. Almost all large peaks contained 4, 5, or 6 unsaturated double bonds in the carbon chain at the sn-2 position of the glycerol backbone. Our results showed that EPls from scallops, lacking pituitary glands, stimulated both FSH and LH secretion by bovine gonadotrophs.

Estrogens and the regulation of glucose metabolism

The main estrogens: estradiol, estrone, and their acyl-esters have been studied essentially related to their classical estrogenic and pharmacologic functions. However, their main effect in the body is probably the sustained control of core energy metabolism. Estrogen nuclear and membrane receptors show an extraordinary flexibility in the modulation of metabolic responses, and largely explain gender and age differences in energy metabolism: part of these mechanisms is already sufficiently known to justify both. With regard to energy, the estrogen molecular species act essentially through four key functions: (1) Facilitation of insulin secretion and control of glucose availability; (2) Modulation of energy partition, favoring the use of lipid as the main energy substrate when more available than carbohydrates; (3) Functional protection through antioxidant mechanisms; and (4) Central effects (largely through neural modulation) on whole body energy management. Analyzing the different actions of estrone, estradiol and their acyl esters, a tentative classification based on structure/effects has been postulated. Either separately or as a group, estrogens provide a comprehensive explanation that not all their quite diverse actions are related solely to specific molecules. As a group, they constitute a powerful synergic action complex. In consequence, estrogens may be considered wardens of energy homeostasis.

Integrative Analysis of Vaginal Microorganisms and Serum Metabolomics in Rats With Estrous Cycle Disorder Induced by Long-Term Heat Exposure Based on 16S rDNA Gene Sequencing and LC/MS-Based Metabolomics

Long term heat exposure (HE) leads to estrous cycle disorder (ECD) in female rats and damages reproductive function. However, the regulation mechanism of vaginal microorganisms and serum metabolomics remains unclear. This study aimed to explore the effects of microbes on the vaginal secretions of rats with ECD and describe the serum metabolomics characteristics and their relationship with vaginal microorganisms. The alterations in the serum levels of neurotransmitters were used to verify the possible regulatory pathways. The relative abundance, composition, and colony interaction network of microorganisms in the vaginal secretions of rats with ECD changed significantly. The metabolomics analysis identified 22 potential biomarkers in the serum including lipid metabolism, amino acid metabolism, and mammalian target of rapamycin and gonadotropin-releasing hormone (GnRH) signaling pathways. Further, 52 pairs of vaginal microbiota–serum metabolites correlations (21 positive and 31 negative) were determined. The abundance of Gardnerella correlated positively with the metabolite L-arginine concentration and negatively with the oleic acid concentration. Further, a negative correlation was found between the abundance of Pseudomonas and the L-arginine concentration and between the metabolite benzoic acid concentration and the abundance of Adlercreutzia. These four bacteria–metabolite pairs had a direct or indirect relationship with the estrous cycle and reproduction. The glutamine, glutamate, and dopamine levels were significantly uncontrolled. The former two were closely related to GnRH signaling pathways involved in the development and regulation of HE-induced ECD in rats. Serum neurotransmitters partly reflected the regulatory effect of vaginal microorganisms on the host of HE-induced ECD, and glutamatergic neurotransmitters might be closely related to the alteration in vaginal microorganisms. These findings might help comprehend the mechanism of HE-induced ECD and propose a new intervention based on vaginal microorganisms.

Discovery of new receptors regulating luteinizing hormone and follicle-stimulating hormone secretion by bovine gonadotrophs to explore a new paradigm for mechanisms regulating reproduction

Previous studies in the 1960s and 1970s have reported that both gonadotropin-releasing hormone (GnRH) and estradiol-activated nuclear estrogen receptors regulate gonadotropin secretion in women. However, I had previously reported that gonadotroph function is regulated by complex crosstalk between several membrane receptors. RNA-seq had previously revealed 259 different receptor genes expressed in the anterior pituitary of heifers. However, the biological roles of most of these receptors remain unknown. I identified four new receptors of interest: G protein-coupled receptor 30 (GPR30), anti-Mullerian hormone (AMH) receptor type 2 (AMHR2), and G protein-coupled receptors 61 and 153 (GPR61 and GPR153). GPR30 rapidly (within a few minutes) mediates picomolar, but not nanomolar, levels of estradiol to suppress GnRH-induced luteinizing hormone (LH) secretion from bovine gonadotrophs, without decreasing mRNA expressions of the LHα, LHβ, or follicle-stimulating hormone (FSH) β subunits. GPR30 is activated by other endogenous estrogens, estrone and estriol. Moreover, GPR30 activation by zearalenone, a nonsteroidal mycoestrogen, suppresses LH secretion. AMHR2, activated by AMH, stimulates LH and FSH secretion, thus regulating gonadotrophs, where other TGF-β family members, including inhibin and activin, potentially affect FSH secretion. I also show that GPR61, activated by its ligand (recently discovered) significantly alters LH and FSH secretion. GPR61, GPR153, and AMHR2 co-localize with the GnRH receptor in unevenly dispersed areas of the bovine gonadotroph cell surface, probably lipid rafts. The findings summarized in this review reveal a new paradigm regarding the mechanisms regulating reproduction via novel receptors expressed on bovine gonadotrophs.

Is the membrane estrogen receptor, GPER1, a promiscuous receptor that modulates nuclear estrogen receptor-mediated functions in the brain?

Contribution to Special Issue on Fast effects of steroids. Estrogen signals both slowly to regulate transcription and rapidly to activate kinases and regulate calcium levels. Both rapid, non-genomic signaling as well as genomic transcriptional signaling via intracellular estrogen receptors (ER)s can change behavior. Rapid non-genomic signaling is initiated from the plasma membrane by a G-protein coupled receptor called GPER1 that binds 17β-estradiol. GPER1 or GPR30 is one of the candidates for a membrane ER (mER) that is not only highly expressed in pathology i.e. cancers but also in several behaviorally-relevant brain regions. In the brain, GPER1 signaling, in response to estrogen, facilitates neuroprotection, social behaviors and cognition. In this review, we describe several notable characteristics of GPER1 such as the ability of several endogenous steroids as well as artificially synthesized molecules to bind the GPER1. In addition, GPER1 is localized to the plasma membrane in breast cancer cell lines but may be present in the endoplasmic reticulum or the Golgi apparatus in the hippocampus. Unusually, GPER1 can also translocate to the perinuclear space from the plasma membrane. We explore the idea that subcellular localization and ligand promiscuity may determine the varied downstream signaling cascades of the activated GPER1. Lastly, we suggest that GPER1 can act as a modulator of ERα-mediated action on a convergent target, spinogenesis, in neurons that in turn drives female social behaviors such as lordosis and social learning.

Influence of brain plasmalogen changes on gonadotropin secretion from the cultured bovine anterior pituitary cells

We recently discovered that the orphan G-protein-coupled receptor (GPR) 61 colocalized with GnRH receptors (GnRHRs) on the surface of most of bovine gonadotrophs. A recent study suggested that ethanolamine plasmalogen (PI) is a ligand for GPR61 in mouse neuroblastoma. Therefore, this study evaluated the hypothesis that PI alters LH and FSH secretion from cultured bovine anterior pituitary (AP) cells. We prepared bovine AP cells from postpubertal heifers (26 mo old) and cultured the cells for 3.5 d. We treated the cells with increasing concentrations (0, 5, 50, 500, 5,000, 50,000, or 500,000 pg/mL) of phosphoethanolamine PI (PEPI) extracted from the bovine brain, or l-α-lysophosphatidylethanolamine PI (LEPI) extracted from the bovine brain, for 5 min before either no treatment or GnRH stimulation. The medium samples were harvested 2 h after culture for LH and FSH assays. Phosphoethanolamine PI (50-500 pg/mL) stimulated (P < 0.05) the basal secretion of FSH but not LH. Phosphoethanolamine PI at 50 pg/mL also enhanced (P < 0.05) GnRH-induced FSH secretion. However, higher doses (500-500,000 pg/mL) of PEPI suppressed GnRH-induced FSH secretion. Moreover, 50 to 500,000 pg/mL PEPI suppressed GnRH-induced LH secretion. None of the tested concentrations of LEPI showed any effect on basal or GnRH-induced LH or FSH secretion. Pretreatment with Sma and Mad pathway inhibitors suppressed FSH secretion induced by PEPI, whereas an extracellular signal-regulated kinase pathway inhibitor blocked the PEPI-induced suppression of GnRH-stimulated LH secretion. Therefore, PEPI, but not LEPI, extracted from the bovine brain, alters FSH and LH secretion from cultured AP cells. Further studies are required to decide whether PEPI binds to GPR61 and whether PEPI plays an important role in the control of gonadotropin secretion from gonadotrophs.

Reconsidering the roles of endogenous estrogens and xenoestrogens: the membrane estradiol receptor G protein-coupled receptor 30 (GPR30) mediates the effects of various estrogens

Estrone (E1) and estriol (E3) are considered “weak” estrogens, which exert suppressive effects through estrogen receptors α and β. However, recent studies have demonstrated that E1 and E3, as well as estradiol (E2), suppress gonadotropin-releasing hormone-induced luteinizing hormone secretion from bovine gonadotrophs via G-protein-coupled receptor 30, which is expressed in various reproductive organs. Currently, there is a lack of fundamental knowledge regarding E1 and E3, including their blood levels. In addition, xenoestrogens may remain in the body over long time periods because of enterohepatic circulation. Therefore, it is time to reconsider the roles of endogenous estrogens and xenoestrogens for reproduction.