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Evans MC, Anderson GM. The Role of RFRP Neurons in the Allostatic Control of Reproductive Function. Int J Mol Sci 2023; 24:15851. [PMID: 37958834 PMCID: PMC10648169 DOI: 10.3390/ijms242115851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 10/30/2023] [Accepted: 10/30/2023] [Indexed: 11/15/2023] Open
Abstract
Reproductive function is critical for species survival; however, it is energetically costly and physically demanding. Reproductive suppression is therefore a physiologically appropriate adaptation to certain ecological, environmental, and/or temporal conditions. This 'allostatic' suppression of fertility enables individuals to accommodate unfavorable reproductive circumstances and safeguard survival. The mechanisms underpinning this reproductive suppression are complex, yet culminate with the reduced secretion of gonadotropin-releasing hormone (GnRH) from the hypothalamus, which in turn suppresses gonadotropin release from the pituitary, thereby impairing gonadal function. The focus of this review will be on the role of RFamide-related peptide (RFRP) neurons in different examples of allostatic reproductive suppression. RFRP neurons release the RFRP-3 peptide, which negatively regulates GnRH neurons and thus appears to act as a 'brake' on the neuroendocrine reproductive axis. In a multitude of predictable (e.g., pre-puberty, reproductive senescence, and seasonal or lactational reproductive quiescence) and unpredictable (e.g., metabolic, immune and/or psychosocial stress) situations in which GnRH secretion is suppressed, the RFRP neurons have been suggested to act as modulators. This review examines evidence for and against these roles.
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Affiliation(s)
| | - Greg M. Anderson
- Centre for Neuroendocrinology and Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin 9016, New Zealand;
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Zhao X, Si L, Niu L, Wei M, Wang F, Liu X, Chen Z, Qiao Y, Cheng L, Yang S. Effects of RFRP‑3 on an ovariectomized estrogen‑primed rat model and HEC‑1A human endometrial carcinoma cells. Exp Ther Med 2022; 25:76. [PMID: 36684658 PMCID: PMC9842939 DOI: 10.3892/etm.2022.11775] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2021] [Accepted: 11/10/2022] [Indexed: 12/24/2022] Open
Abstract
The hypothalamic peptide gonadotropin inhibitory hormone (GnIH) is a relatively novel hypothalamic neuropeptide, identified in 2000. It can influence the hypothalamic-pituitary-gonadal axis and reproductive function through various neuroendocrine systems. The present study aimed to explore the effects and potential underlying molecular mechanism of RFamide-related peptide-3 (RFRP-3) injection on the uterine fluid protein profile of ovariectomized estrogen-primed (OEP) rats using proteomics. In addition, the possible effects of RFRP-3 on the viability and apoptosis of the human endometrial cancer cell line HEC-1A and associated molecular mechanism were investigated. The OEP rat model was established through injection with GnIH/RFRP-3 through the lateral ventricle. At 6 h after injection, the protein components of uterine fluid of rats in the experimental and control groups were analyzed using liquid chromatography (LC)-tandem mass spectrometry (MS/MS). Differentially expressed proteins (DEPs) were analyzed using the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. Protein-protein interactions (PPI) were investigated using the STRING database. PPI networks were then established before hub proteins were selected using OmicsBean software. The expression of one of the hub proteins, Kras, was then detected using western blot analysis. Cell Counting Kit-8, Annexin V-FITC/PI, reverse transcription-quantitative PCR and western blotting were also performed to analyze cell viability and apoptosis. In total, 417 DEPs were obtained using LC-MS/MS, including 279 upregulated and 138 downregulated proteins. GO analysis revealed that the majority of the DEPs were secretory proteins. According to KEGG enrichment analysis, the DEPs found were generally involved in tumor-associated pathways. In particular, five hub proteins, namely G protein subunit α (Gna)13, Gnaq, Gnai3, Kras and MMP9, were obtained following PPI network analysis. Western blot analysis showed that expression of the hub protein Kras was downregulated following treatment with 10,000 ng/ml RFRP-3. RFRP-3 treatment (10,000 ng/ml) also suppressed HEC-1A cell viability, induced apoptosis, downregulated Bcl-2 and upregulated Bax protein expression, compared with those in the control group. In addition, compared with those in the control group, RFRP-3 significantly reduced the mRNA expression levels of PI3K, AKT and mTOR, while upregulating those of LC3-II. Compared with those in the control group, RFRP-3 significantly decreased the protein expression levels of PI3K, AKT, mTOR and p62, in addition to decreasing AKT phosphorylation. By contrast, RFRP-3 significantly increased the LC3-II/I ratio and G protein-coupled receptor 147 (GPR147) protein expression. In conclusion, the present data suggest that RFRP-3 can alter the protein expression profile of the uterine fluid of OEP rats by upregulating MMP9 expression whilst downregulating that of key hub proteins Gna13, GnaQ, Gnai3 and Kras. Furthermore, RFRP-3 can inhibit HEC-1A cell viability while promoting apoptosis. The underlying molecular mechanism may involve activation of GPR147 receptor by the direct binding of RFRP-3, which further downregulates the hub protein Kras to switch on the PI3K/AKT/mTOR pathway. This subsequently reduces the Bcl-2 expression and promotes Bax expression to induce autophagy.
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Affiliation(s)
- Xueying Zhao
- Department of Immunology, Chengde Medical University, Chengde, Hebei 067000, P.R. China
| | - Lina Si
- Department of Human Anatomy, Chengde Medical University, Chengde, Hebei 067000, P.R. China
| | - Lin Niu
- Department of Human Anatomy, Chengde Medical University, Chengde, Hebei 067000, P.R. China
| | - Meng Wei
- Department of Human Anatomy, Chengde Medical University, Chengde, Hebei 067000, P.R. China
| | - Fengxia Wang
- Department of Human Anatomy, Chengde Medical University, Chengde, Hebei 067000, P.R. China
| | - Xiaochao Liu
- Department of Human Anatomy, Chengde Medical University, Chengde, Hebei 067000, P.R. China
| | - Zhihong Chen
- Department of Human Anatomy, Chengde Medical University, Chengde, Hebei 067000, P.R. China
| | - Yuebing Qiao
- Department of Human Anatomy, Chengde Medical University, Chengde, Hebei 067000, P.R. China
| | - Luyang Cheng
- Department of Immunology, Chengde Medical University, Chengde, Hebei 067000, P.R. China,Correspondence to: Mrs. Luyang Cheng, Department of Immunology, Chengde Medical University, Anyuan Road, Shuangqiao, Chengde, Hebei 067000, P.R. China
| | - Songhe Yang
- Department of Human Anatomy, Chengde Medical University, Chengde, Hebei 067000, P.R. China,Correspondence to: Mrs. Luyang Cheng, Department of Immunology, Chengde Medical University, Anyuan Road, Shuangqiao, Chengde, Hebei 067000, P.R. China
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Bulut F, Kacar E, Bilgin B, Hekim MG, Keleştemur MM, Sahin Z, Ayar A, Ozcan M. Crosstalk between kisspeptin and gonadotropin-inhibitory hormone in the silence of puberty: preclinical evidence from a calcium signaling study. J Recept Signal Transduct Res 2022; 42:608-613. [PMID: 36137227 DOI: 10.1080/10799893.2022.2125014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Kisspeptin and gonadotropin-inhibitory hormone (GnIH) are among suggested neuroendocrine modulators of reproductive function. Intracellular calcium signaling is a critical component in the regulation of a variety of physiological and pathological processes including neurotransmitter release, and, therefore, can be used as signaling indicator for investigating the involvement of kisspeptin, GnIH, and gonadotropin-releasing hormone (GnRH) release. Hence, this study investigated the effects of kisspeptin and GnIH on calcium signaling using immortalized hypothalamic cells (rHypoE-8) as a model. Kisspeptin neurons were loaded with the ratiometric calcium dye (Fura-2 AM, 1 μmol) and intracellular free calcium ([Ca2+]i) responses were quantified using digital fluorescence imaging system. Kisspeptin-10 (100, 300, and 1000 nM) caused a significant increase in [Ca2+]i in rHypoE-8 cells (n = 58, n = 64, and n = 49, respectively, p < 0.001). The kisspeptin receptor antagonist, P234, inhibited the calcium responses to kisspeptin (p < 0.001, n = 32). GnIH (100 and 1000 nM), alone, did not cause any significant change in the mean basal [Ca2+]i levels in kisspeptin cells, but GnIH attenuated the kisspeptin-evoked [Ca2+]i transients (n = 47, p < 0.001). This novel findings of [Ca2+]i signaling in in vitro setting implicate that kisspeptin and GnIH may exert their effects on hypothalamus-pituitary-gonadal (HPG) axis by modulating kisspeptin neurons. These results also implicate that kisspeptin neurons may have an autocrine regulation.
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Affiliation(s)
- Ferah Bulut
- Department of Biophysics, Faculty of Medicine, Firat University, Elazig, Turkey
| | - Emine Kacar
- Department of Physiology, Faculty of Medicine, Firat University, Elazig, Turkey
| | - Batuhan Bilgin
- Department of Biophysics, Faculty of Medicine, Firat University, Elazig, Turkey
| | | | | | - Zafer Sahin
- Department of Physiology, Faculty of Medicine, Karadeniz Technical University, Trabzon, Turkey
| | - Ahmet Ayar
- Department of Physiology, Faculty of Medicine, Karadeniz Technical University, Trabzon, Turkey
| | - Mete Ozcan
- Department of Biophysics, Faculty of Medicine, Firat University, Elazig, Turkey
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Khan S, Batool B, Zubair H, Bano R, Ahmad S, Shahab M. Expression and co-localization of RFRP-3 and kisspeptin during breeding and non-breeding season in the hypothalamus of male rhesus monkey ( Macaca mulatta). Reprod Med Biol 2022; 21:e12479. [PMID: 35847413 PMCID: PMC9270642 DOI: 10.1002/rmb2.12479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 06/12/2022] [Accepted: 06/21/2022] [Indexed: 12/01/2022] Open
Abstract
Propose The mechanism that underpins how RFRP‐3 and kisspeptin interacts are not fully understood in higher primates. This study therefore set out to assess RFRP‐3 and kisspeptin expression and their morphological interactions in the breeding, and in the non‐breeding period in monkey hypothalamus. Methods Eight mature male macaques (Macaca mulatta) in the breeding season (February; n = 4) and non‐breeding season (June; n = 4) were used. To reveal the expression and co‐localization of RFRP‐3 and kisspeptin, double‐labeled immunohistochemistry was performed. Testicular volume, sperm count, and plasma testosterone level were also measured to validate the breeding and non‐breeding paradigms. Results Testicular volume, plasma testosterone level, and sperm count showed a significant reduction during non‐breeding season. The number of kisspeptin‐positive cells was significantly increased during the breeding season (p < 0.05), whereas more RFRP‐3‐positive cell bodies were seen in the non‐breeding season (p < 0.01). Close contacts of RFRP‐3 fibers with kisspeptin cells showed no significant difference (p > 0.05) across seasons. However, co‐localization of RFRP‐3‐ir cell bodies onto kisspeptin IR cell bodies showed a statistical increase (p < 0.01) in non‐breeding season. Conclusion In higher primates, RFRP‐3 decreases kisspeptin drives from the same cells to GnRH neurons in an autocrine manner causing suppression of the reproductive axis during the non‐breeding period.
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Affiliation(s)
- Safdar Khan
- Department of Zoology, Laboratory of Reproductive Neuroendocrinology, Faculty of Biological Sciences Quaid-i-Azam University Islamabad Pakistan
| | - Bakhtwar Batool
- Department of Zoology, Laboratory of Reproductive Neuroendocrinology, Faculty of Biological Sciences Quaid-i-Azam University Islamabad Pakistan
| | - Hira Zubair
- Department of Zoology, Laboratory of Reproductive Neuroendocrinology, Faculty of Biological Sciences Quaid-i-Azam University Islamabad Pakistan
| | - Riffat Bano
- Department of Zoology, Laboratory of Reproductive Neuroendocrinology, Faculty of Biological Sciences Quaid-i-Azam University Islamabad Pakistan
| | - Shakil Ahmad
- Department of Zoology, Laboratory of Reproductive Neuroendocrinology, Faculty of Biological Sciences Quaid-i-Azam University Islamabad Pakistan
| | - Muhammad Shahab
- Department of Zoology, Laboratory of Reproductive Neuroendocrinology, Faculty of Biological Sciences Quaid-i-Azam University Islamabad Pakistan.,Shaheed Benazir Bhutto University, Sheringal Dir Upper Pakistan
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