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Grant AD, Kriegsfeld LJ. Neural substrates underlying rhythmic coupling of female reproductive and thermoregulatory circuits. Front Physiol 2023; 14:1254287. [PMID: 37753455 PMCID: PMC10518419 DOI: 10.3389/fphys.2023.1254287] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 08/30/2023] [Indexed: 09/28/2023] Open
Abstract
Coordinated fluctuations in female reproductive physiology and thermoregulatory output have been reported for over a century. These changes occur rhythmically at the hourly (ultradian), daily (circadian), and multi-day (ovulatory) timescales, are critical for reproductive function, and have led to the use of temperature patterns as a proxy for female reproductive state. The mechanisms underlying coupling between reproductive and thermoregulatory systems are not fully established, hindering the expansion of inferences that body temperature can provide about female reproductive status. At present, numerous digital tools rely on temperature to infer the timing of ovulation and additional applications (e.g., monitoring ovulatory irregularities and progression of puberty, pregnancy, and menopause are developed based on the assumption that reproductive-thermoregulatory coupling occurs across timescales and life stages. However, without clear understanding of the mechanisms and degree of coupling among the neural substrates regulating temperature and the reproductive axis, whether such approaches will bear fruit in particular domains is uncertain. In this overview, we present evidence supporting broad coupling among the central circuits governing reproduction, thermoregulation, and broader systemic physiology, focusing on timing at ultradian frequencies. Future work characterizing the dynamics of reproductive-thermoregulatory coupling across the lifespan, and of conditions that may decouple these circuits (e.g., circadian disruption, metabolic disease) and compromise female reproductive health, will aid in the development of strategies for early detection of reproductive irregularities and monitoring the efficacy of fertility treatments.
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Affiliation(s)
| | - Lance J. Kriegsfeld
- Department of Psychology, University of California, Berkeley, CA, United States
- The Helen Wills Neuroscience Institute, University of California, Berkeley, CA, United States
- Department of Integrative Biology, University of California, Berkeley, CA, United States
- Graduate Group in Endocrinology, University of California, Berkeley, CA, United States
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Liu T, Bowen RL, Wilson AC, Atwood CS. Estropause, Sex Hormones and Metal Homeostasis in the Mouse Brain. Front Neurol 2022; 13:841822. [PMID: 35645980 PMCID: PMC9130555 DOI: 10.3389/fneur.2022.841822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 02/07/2022] [Indexed: 12/02/2022] Open
Abstract
Alterations in brain metal ion homeostasis have been reported with aging and are implicated in the pathogenesis of neurodegenerative diseases. To assess whether age-related changes in hypothalamic-pituitary-gonadal (HPG) hormones might be involved in modulating brain metal ion homeostasis, we treated 7.5-month intact, sham-ovariecomized and ovariectomized C57B6SJL mice with vehicle or leuprolide acetate (for 9-months) to differentiate between whether sex steroids or gonadotropins might modulate brain metal ion concentrations. Unlike other aging mammals, there was no increase in plasma luteinizing hormone (LH) and follicle-stimulating hormone (FSH) concentrations following estropause in mice, suggesting there was sufficient residual production by the follicle depleted ovary, of sex steroids like estrogens and protein hormones like the inhibins, in order to suppress pituitary LH/FSH production. Castration on the other hand induced significant increases in circulating LH and FSH. Modulation of plasma sex steroid and gonadotropin levels did not significantly alter the concentrations of brain metals tested (Fe, Zn, Cu, Mn, Co, Ni, Al, Li), although there was a tendency for a decrease in all brain metals following ovariectomy (low estrogens and progesterone, high gonadotropins), a response that was reversed with leuprolide acetate treatment (low sex steroids, low gonadotropins). Brain Cu concentration was the only metal correlated with plasma LH (−0.37, n = 30, p < 0.05) and FSH (−0.42, n = 29, p < 0.01). This study demonstrates that sex hormones do not markedly alter brain metal ion homeostasis, unlike previously reported studies of circulating metal ion homeostasis. The role of gonadotropins in regulating metal ion homeostasis does however warrant further study.
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Affiliation(s)
- Tianbing Liu
- Institute of Pathology, Case Western Reserve University School of Medicine, Cleveland, OH, United States
- Department of Pathology and Laboratory Medicine, University of Wisconsin Madison School of Medicine and Public Health, Madison, WI, United States
| | | | - Andrea C. Wilson
- Institute of Pathology, Case Western Reserve University School of Medicine, Cleveland, OH, United States
- Department of Pathology and Laboratory Medicine, University of Wisconsin Madison School of Medicine and Public Health, Madison, WI, United States
| | - Craig S. Atwood
- Institute of Pathology, Case Western Reserve University School of Medicine, Cleveland, OH, United States
- Division of Geriatrics and Gerontology, Department of Medicine, University of Wisconsin Madison School of Medicine and Public Health, Madison, WI, United States
- Geriatric Research, Education and Clinical Center, Veterans Administration Hospital, Madison, WI, United States
- School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia
- *Correspondence: Craig S. Atwood
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Bacon ER, Brinton RD. Epigenetics of the developing and aging brain: Mechanisms that regulate onset and outcomes of brain reorganization. Neurosci Biobehav Rev 2021; 125:503-516. [PMID: 33657435 DOI: 10.1016/j.neubiorev.2021.02.040] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 02/17/2021] [Accepted: 02/23/2021] [Indexed: 12/11/2022]
Abstract
Brain development is a life-long process that encompasses several critical periods of transition, during which significant cognitive changes occur. Embryonic development, puberty, and reproductive senescence are all periods of transition that are hypersensitive to environmental factors. Rather than isolated episodes, each transition builds upon the last and is influenced by consequential changes that occur in the transition before it. Epigenetic marks, such as DNA methylation and histone modifications, provide mechanisms by which early events can influence development, cognition, and health outcomes. For example, parental environment influences imprinting patterns in gamete cells, which ultimately impacts gene expression in the embryo which may result in hypersensitivity to poor maternal nutrition during pregnancy, raising the risks for cognitive impairment later in life. This review explores how epigenetics induce and regulate critical periods, and also discusses how early environmental interactions prime a system towards a particular health outcome and influence susceptibility to disease or cognitive impairment throughout life.
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Affiliation(s)
- Eliza R Bacon
- Department of Neuroscience, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, CA, 90089, USA; The Center for Precision Medicine, Beckman Research Institute, City of Hope, Duarte, CA, 91010, USA
| | - Roberta Diaz Brinton
- Department of Neuroscience, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, CA, 90089, USA; Center for Innovation in Brain Science, School of Medicine, University of Arizona, Tucson, AZ, 85721, USA.
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Grant AD, Newman M, Kriegsfeld LJ. Ultradian rhythms in heart rate variability and distal body temperature anticipate onset of the luteinizing hormone surge. Sci Rep 2020; 10:20378. [PMID: 33230235 PMCID: PMC7683606 DOI: 10.1038/s41598-020-76236-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 10/20/2020] [Indexed: 11/13/2022] Open
Abstract
The menstrual cycle is characterized by predictable patterns of physiological change across timescales. Although patterns of reproductive hormones across the menstrual cycle, particularly ultradian rhythms, are well described, monitoring these measures repeatedly to predict the preovulatory luteinizing hormone (LH) surge is not practical. In the present study, we explored whether non-invasive measures coupled to the reproductive system: high frequency distal body temperature (DBT), sleeping heart rate (HR), sleeping heart rate variability (HRV), and sleep timing, could be used to anticipate the preovulatory LH surge in women. To test this possibility, we used signal processing to examine these measures in 45 premenopausal and 10 perimenopausal cycles alongside dates of supra-surge threshold LH and menstruation. Additionally, urinary estradiol and progesterone metabolites were measured daily surrounding the LH surge in 20 cycles. Wavelet analysis revealed a consistent pattern of DBT and HRV ultradian rhythm (2-5 h) power that uniquely enabled anticipation of the LH surge at least 2 days prior to its onset in 100% of individuals. Together, the present findings reveal fluctuations in distal body temperature and heart rate variability that consistently anticipate the LH surge, suggesting that automated ultradian rhythm monitoring may provide a novel and convenient method for non-invasive fertility assessment.
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Affiliation(s)
- Azure D Grant
- The Helen Wills Neuroscience Institute, University of California, 175 Li Ka Shing Center, MC # 3370, Berkeley, CA, 94720, USA
| | - Mark Newman
- Precision Analytical, McMinnville, OR, 97128, USA
| | - Lance J Kriegsfeld
- The Helen Wills Neuroscience Institute, University of California, 175 Li Ka Shing Center, MC # 3370, Berkeley, CA, 94720, USA.
- Department of Psychology, University of California, Berkeley, CA, 94720, USA.
- Department of Integrative Biology, University of California, Berkeley, CA, 94720, USA.
- Graduate Group in Endocrinology, University of California, Berkeley, CA, 94720, USA.
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Szeliga A, Czyzyk A, Podfigurna A, Genazzani AR, Genazzani AD, Meczekalski B. The role of kisspeptin/neurokinin B/dynorphin neurons in pathomechanism of vasomotor symptoms in postmenopausal women: from physiology to potential therapeutic applications. Gynecol Endocrinol 2018; 34:913-919. [PMID: 29902942 DOI: 10.1080/09513590.2018.1480711] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Women during perimenopausal period experience a range of symptoms, which interfere with physical, sexual, and social life. About 65-75% of symptoms connected with postmenopausal period are vasomotor symptoms (VMS), such as hot flushes and night sweats. Hot flushes are subjective sensation of heat associated with cutaneous vasodilatation and drop in core temperature. It is suspected that VMS are strongly correlated with pulsatile oversecretion of gonadotropin-releasing hormone (GnRH) and subsequently luteinizing hormone (LH). Evidence has accumulated in parallel showing that lack of negative feedback of steroid hormones synthesized in ovary causes overactivation of hypertrophied kisspeptin/neurokinin B/dynorphin (KNDy) neurons, located in infundibular nucleus. Oversecretion of both kisspeptin (KISS1) and neurokinin B (NKB), as well as downregulation of dynorphin, plays dominant role in creation of GnRH pulses. This in turn causes VMS. Administration of senktide, highly potent and selective NK3R agonist, resulted in increase of serum LH concentration, induction of VMS, increase in heart rate, and skin temperature in postmenopausal women. These finding suggest that modulation of KNDy neurons may become new therapeutic approach in the treatment of VMS.
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Affiliation(s)
- Anna Szeliga
- a Department of Gynecological Endocrinology , Poznan University of Medical Sciences , Poznan , Poland
| | - Adam Czyzyk
- a Department of Gynecological Endocrinology , Poznan University of Medical Sciences , Poznan , Poland
| | - Agnieszka Podfigurna
- a Department of Gynecological Endocrinology , Poznan University of Medical Sciences , Poznan , Poland
| | - Andrea R Genazzani
- b Department of Reproductive Medicine and Child Development, Division of Gynecology and Obstetrics , University of Pisa , Pisa , Italy
| | - Alessandro D Genazzani
- c Department of Obstetrics and Gynecology , Gynecological Endocrinology Center, University of Modena and Reggio Emilia , Modena , Italy
| | - Blazej Meczekalski
- a Department of Gynecological Endocrinology , Poznan University of Medical Sciences , Poznan , Poland
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6
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Grant AD, Wilsterman K, Smarr BL, Kriegsfeld LJ. Evidence for a Coupled Oscillator Model of Endocrine Ultradian Rhythms. J Biol Rhythms 2018; 33:475-496. [PMID: 30132387 DOI: 10.1177/0748730418791423] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Whereas long-period temporal structures in endocrine dynamics have been well studied, endocrine rhythms on the scale of hours are relatively unexplored. The study of these ultradian rhythms (URs) has remained nascent, in part, because a theoretical framework unifying ultradian patterns across systems has not been established. The present overview proposes a conceptual coupled oscillator network model of URs in which oscillating hormonal outputs, or nodes, are connected by edges representing the strength of node-node coupling. We propose that variable-strength coupling exists both within and across classic hormonal axes. Because coupled oscillators synchronize, such a model implies that changes across hormonal systems could be inferred by surveying accessible nodes in the network. This implication would at once simplify the study of URs and open new avenues of exploration into conditions affecting coupling. In support of this proposed framework, we review mammalian evidence for (1) URs of the gut-brain axis and the hypothalamo-pituitary-thyroid, -adrenal, and -gonadal axes, (2) UR coupling within and across these axes; and (3) the relation of these URs to body temperature. URs across these systems exhibit behavior broadly consistent with a coupled oscillator network, maintaining both consistent URs and coupling within and across axes. This model may aid the exploration of mammalian physiology at high temporal resolution and improve the understanding of endocrine system dynamics within individuals.
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Affiliation(s)
- Azure D Grant
- The Helen Wills Neuroscience Institute, University of California, Berkeley, California
| | - Kathryn Wilsterman
- Department of Integrative Biology, University of California, Berkeley, California
| | - Benjamin L Smarr
- Department of Psychology, University of California, Berkeley, California
| | - Lance J Kriegsfeld
- The Helen Wills Neuroscience Institute, University of California, Berkeley, California.,Department of Psychology, University of California, Berkeley, California
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Barardo DG, Newby D, Thornton D, Ghafourian T, de Magalhães JP, Freitas AA. Machine learning for predicting lifespan-extending chemical compounds. Aging (Albany NY) 2017; 9:1721-1737. [PMID: 28783712 PMCID: PMC5559171 DOI: 10.18632/aging.101264] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 07/12/2017] [Indexed: 12/12/2022]
Abstract
Increasing age is a risk factor for many diseases; therefore developing pharmacological interventions that slow down ageing and consequently postpone the onset of many age-related diseases is highly desirable. In this work we analyse data from the DrugAge database, which contains chemical compounds and their effect on the lifespan of model organisms. Predictive models were built using the machine learning method random forests to predict whether or not a chemical compound will increase Caenorhabditis elegans' lifespan, using as features Gene Ontology (GO) terms annotated for proteins targeted by the compounds and chemical descriptors calculated from each compound's chemical structure. The model with the best predictive accuracy used both biological and chemical features, achieving a prediction accuracy of 80%. The top 20 most important GO terms include those related to mitochondrial processes, to enzymatic and immunological processes, and terms related to metabolic and transport processes. We applied our best model to predict compounds which are more likely to increase C. elegans' lifespan in the DGIdb database, where the effect of the compounds on an organism's lifespan is unknown. The top hit compounds can be broadly divided into four groups: compounds affecting mitochondria, compounds for cancer treatment, anti-inflammatories, and compounds for gonadotropin-releasing hormone therapies.
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Affiliation(s)
- Diogo G. Barardo
- Integrative Genomics of Ageing Group, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK
| | - Danielle Newby
- Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, UK
| | - Daniel Thornton
- Integrative Genomics of Ageing Group, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK
| | | | - João Pedro de Magalhães
- Integrative Genomics of Ageing Group, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK
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Atwood CS, Hayashi K, Meethal SV, Gonzales T, Bowen RL. Does the degree of endocrine dyscrasia post-reproduction dictate post-reproductive lifespan? Lessons from semelparous and iteroparous species. GeroScience 2017; 39:103-116. [PMID: 28271270 PMCID: PMC5352586 DOI: 10.1007/s11357-016-9955-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 12/23/2016] [Indexed: 12/16/2022] Open
Abstract
Post-reproductive lifespan varies greatly among species; human post-reproductive lifespan comprises ~30-50% of their total longevity, while semelparous salmon and dasyurid marsupials post-reproductive lifespan comprises <4% of their total longevity. To examine if the magnitude of hypothalamic-pituitary-gonadal (HPG) axis dyscrasia at the time of reproductive senescence determines post-reproductive lifespan, we examined the difference between pre- and post-reproductive (1) circulating sex hormones and (2) the ratio of sex steroids to gonadotropins (e.g., 17β-estradiol/follicle-stimulating hormone (FSH)), an index of the dysregulation of the HPG axis and the level of dyotic (death) signaling post-reproduction. Animals with a shorter post-reproductive lifespan (<4% total longevity) had a more marked decline in circulating sex steroids and corresponding elevation in gonadotropins compared to animals with a longer post-reproductive lifespan (30-60% total longevity). In semelparous female salmon of short post-reproductive lifespan (1%), these divergent changes in circulating hormone concentration post-reproduction equated to a 711-fold decrease in the ratio of 17β-estradiol/FSH between the reproductive and post-reproductive periods. In contrast, the decrease in the ratio of 17β-estradiol/FSH in iteroparous female mammals with long post-reproductive lifespan was significantly less (1.7-34-fold) post-reproduction. Likewise, in male semelparous salmon, the decrease in the ratio of testosterone/FSH (82-fold) was considerably larger than for iteroparous species (1.3-11-fold). These results suggest that (1) organisms with greater reproductive endocrine dyscrasia more rapidly undergo senescence and die, and (2) the contribution post-reproduction by non-gonadal (and perhaps gonadal) tissues to circulating sex hormones dictates post-reproductive tissue health and longevity. In this way, reproduction and longevity are coupled, with the degree of non-gonadal tissue hormone production dictating the rate of somatic tissue demise post-reproduction and the differences in post-reproductive lifespans between species.
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Affiliation(s)
- Craig S Atwood
- Division of Geriatrics and Gerontology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, William S. Middleton Memorial VA (GRECC 11G), 2500 Overlook Terrace, Madison, WI, 53705, USA.
- Geriatric Research, Education and Clinical Center, Veterans Administration Hospital, Madison, WI, 53705, USA.
- School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Joondalup, WA, 6027, Australia.
| | - Kentaro Hayashi
- Division of Geriatrics and Gerontology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, William S. Middleton Memorial VA (GRECC 11G), 2500 Overlook Terrace, Madison, WI, 53705, USA
| | - Sivan Vadakkadath Meethal
- Division of Geriatrics and Gerontology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, William S. Middleton Memorial VA (GRECC 11G), 2500 Overlook Terrace, Madison, WI, 53705, USA
| | - Tina Gonzales
- Division of Geriatrics and Gerontology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, William S. Middleton Memorial VA (GRECC 11G), 2500 Overlook Terrace, Madison, WI, 53705, USA
| | - Richard L Bowen
- Department of Psychiatry, Medical University of South Carolina, Charleston, SC, 29425, USA
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Chakraborty TR, Gore AC. Aging-Related Changes in Ovarian Hormones, Their Receptors, and Neuroendocrine Function. Exp Biol Med (Maywood) 2016; 229:977-87. [PMID: 15522833 DOI: 10.1177/153537020422901001] [Citation(s) in RCA: 129] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Ovarian steroid hormones exert a broad range of effects on the body and brain. In the nervous system, estrogen and progesterone have crucial feedback actions on the hypothalamic neurons that drive the reproductive axis. In addition, hormones exert a variety of actions on other traditionally nonreproductive functions such as cognition, learning and memory, neuroprotection, mood and affective behavior, and locomotor activity. The actions of hormones on the hypothalamus are largely mediated by their nuclear hormone receptors, the two estrogen receptors, ERα and ERβ, and the two progesterone receptor isoforms, PR-A and PR-B. Thus, changes in the circulating concentrations of estrogens and progestins during the life cycle can result in differential activation of their receptors. Furthermore, changes in the numbers, activity, and distribution of hypothalamic ERs and PRs can occur as a function of developmental age. The purpose of this article is to review the literature on the causes and consequences of alterations in steroid hormones, their neural receptors, and their interactions on reproductive senescence. We have also discussed several important experimental design considerations, focusing on rodent models in current use for understanding the mechanisms of menopause in women.
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Affiliation(s)
- Tandra R Chakraborty
- Fishberg Research Center for Neurobiology, Mount Sinai School of Medicine, New York, New York 10029, USA
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Abstract
The rhesus macaque (Macaca mulatta) is one of the most extensively used nonhuman primate models for human diseases. This article presents a literature review focusing on major organ systems and age-associated conditions in humans and primates, combined with information from the Wisconsin National Primate Research Center Electronic Health Record database to highlight and contrast age-associated lesions in geriatric rhesus macaques with younger cohorts. Rhesus macaques are excellent models for age-associated conditions, including diabetes, osteoarthritis, endometriosis, visual accommodation, hypertension, osteoporosis, and amyloidosis. Adenocarcinoma of the large intestine (ileocecocolic junction, cecum, and colon) is the most common spontaneous neoplasm in the rhesus macaque. A combination of cross-sectional and longitudinal studies is required to truly define mechanisms of maturation, aging, and the pathology of age-associated conditions in macaques and thus humans. The rhesus macaque is and will continue to be an appropriate and valuable model for investigation of the mechanisms and treatment of age-associated diseases.
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Affiliation(s)
- H A Simmons
- Wisconsin National Primate Research Center, University of Wisconsin-Madison, Madison, WI, USA
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Naugle MM, Lozano SA, Guarraci FA, Lindsey LF, Kim JE, Morrison JH, Janssen WG, Yin W, Gore AC. Age and Long-Term Hormone Treatment Effects on the Ultrastructural Morphology of the Median Eminence of Female Rhesus Macaques. Neuroendocrinology 2016; 103:650-64. [PMID: 26536204 PMCID: PMC4860175 DOI: 10.1159/000442015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 10/29/2015] [Indexed: 12/26/2022]
Abstract
The median eminence (ME) of the hypothalamus comprises the hypothalamic nerve terminals, glia (especially tanycytes) and the portal capillary vasculature that transports hypothalamic neurohormones to the anterior pituitary gland. The ultrastructure of the ME is dynamically regulated by hormones and undergoes organizational changes during development and reproductive cycles in adult females, but relatively little is known about the ME during aging, especially in nonhuman primates. Therefore, we used a novel transmission scanning electron microscopy technique to examine the cytoarchitecture of the ME of young and aged female rhesus macaques in a preclinical monkey model of menopausal hormone treatments. Rhesus macaques were ovariectomized and treated for 2 years with vehicle, estradiol (E2), or estradiol + progesterone (E2 + P4). While the overall cytoarchitecture of the ME underwent relatively few changes with age and hormones, changes to some features of neural and glial components near the portal capillaries were observed. Specifically, large neuroterminal size was greater in aged compared to young adult animals, an effect that was mitigated or reversed by E2 alone but not by E2 + P4 treatment. Overall glial size and the density and tissue fraction of the largest subset of glia were greater in aged monkeys, and in some cases reversed by E2 treatment. Mitochondrial size was decreased by E2, but not E2 + P4, only in aged macaques. These results contrast substantially with work in rodents, suggesting that the ME of aging macaques is less vulnerable to age-related disorganization, and that the effects of E2 on monkeys' ME are age specific.
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Affiliation(s)
| | - Sateria A. Lozano
- Division of Pharmacology & Toxicology, University of Texas at Austin, Austin, TX
| | - Fay A. Guarraci
- Department of Psychology, Southwestern University, Georgetown, TX
| | - Larry F. Lindsey
- Center for Learning and Memory, University of Texas at Austin, Austin, TX
| | - Ji E. Kim
- Division of Pharmacology & Toxicology, University of Texas at Austin, Austin, TX
| | - John H. Morrison
- Fishberg Department of Neuroscience and the Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - William G.M. Janssen
- Fishberg Department of Neuroscience and the Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Weiling Yin
- Division of Pharmacology & Toxicology, University of Texas at Austin, Austin, TX
| | - Andrea C. Gore
- Institute for Neuroscience, University of Texas at Austin, Austin, TX
- Division of Pharmacology & Toxicology, University of Texas at Austin, Austin, TX
- Institute for Cellular & Molecular Biology, University of Texas at Austin, Austin, TX
- Correspondence: Andrea C Gore, PhD, The University of Texas at Austin, 107 West Dean Keeton, C0875, Austin, TX, 78712, USA, ; Tel: +1-512-471-3669; Fax: +1-512-471-5002
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Atwood CS, Bowen RL. The endocrine dyscrasia that accompanies menopause and andropause induces aberrant cell cycle signaling that triggers re-entry of post-mitotic neurons into the cell cycle, neurodysfunction, neurodegeneration and cognitive disease. Horm Behav 2015; 76:63-80. [PMID: 26188949 PMCID: PMC4807861 DOI: 10.1016/j.yhbeh.2015.06.021] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 06/23/2015] [Accepted: 06/23/2015] [Indexed: 12/26/2022]
Abstract
This article is part of a Special Issue "SBN 2014". Sex hormones are physiological factors that promote neurogenesis during embryonic and fetal development. During childhood and adulthood these hormones support the maintenance of brain structure and function via neurogenesis and the formation of dendritic spines, axons and synapses required for the capture, processing and retrieval of information (memories). Not surprisingly, changes in these reproductive hormones that occur with menopause and during andropause are strongly correlated with neurodegeneration and cognitive decline. In this connection, much evidence now indicates that Alzheimer's disease (AD) involves aberrant re-entry of post-mitotic neurons into the cell cycle. Cell cycle abnormalities appear very early in the disease, prior to the appearance of plaques and tangles, and explain the biochemical, neuropathological and cognitive changes observed with disease progression. Intriguingly, a recent animal study has demonstrated that induction of adult neurogenesis results in the loss of previously encoded memories while decreasing neurogenesis after memory formation during infancy mitigated forgetting. Here we review the biochemical, epidemiological and clinical evidence that alterations in sex hormone signaling associated with menopause and andropause drive the aberrant re-entry of post-mitotic neurons into an abortive cell cycle that leads to neurite retraction, neuron dysfunction and neuron death. When the reproductive axis is in balance, gonadotropins such as luteinizing hormone (LH), and its fetal homolog, human chorionic gonadotropin (hCG), promote pluripotent human and totipotent murine embryonic stem cell and neuron proliferation. However, strong evidence supports menopausal/andropausal elevations in the LH:sex steroid ratio as driving aberrant mitotic events. These include the upregulation of tumor necrosis factor; amyloid-β precursor protein processing towards the production of mitogenic Aβ; and the activation of Cdk5, a key regulator of cell cycle progression and tau phosphorylation (a cardinal feature of both neurogenesis and neurodegeneration). Cognitive and biochemical studies confirm the negative consequences of a high LH:sex steroid ratio on dendritic spine density and human cognitive performance. Prospective epidemiological and clinical evidence in humans supports the premise that rebalancing the ratio of circulating gonadotropins:sex steroids reduces the incidence of AD. Together, these data support endocrine dyscrasia and the subsequent loss of cell cycle control as an important etiological event in the development of neurodegenerative diseases including AD, stroke and Parkinson's disease.
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Affiliation(s)
- Craig S Atwood
- Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53705, USA; Geriatric Research, Education and Clinical Center, Veterans Administration Hospital, Madison, WI 53705, USA; School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Joondalup, 6027 WA, Australia.
| | - Richard L Bowen
- OTB Research, 217 Calhoun St, Unit 1, Charleston, SC 29401, USA
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13
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Verdile G, Asih PR, Barron AM, Wahjoepramono EJ, Ittner LM, Martins RN. The impact of luteinizing hormone and testosterone on beta amyloid (Aβ) accumulation: Animal and human clinical studies. Horm Behav 2015; 76:81-90. [PMID: 26122291 DOI: 10.1016/j.yhbeh.2015.05.020] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 05/20/2015] [Accepted: 05/25/2015] [Indexed: 12/31/2022]
Abstract
This article is part of a Special Issue "SBN 2014". Hormonal changes associated with ageing have been implicated in the pathogenesis of Alzheimer's disease (AD), the most common form of dementia. Reductions in serum testosterone and increases in luteinizing hormone (LH) are established AD risk factors for dementia in men and have important roles in modulating AD pathogenesis. One of the defining features of AD is the accumulation of amyloid-beta (Aβ) in the brain, which has a key role in the neurodegenerative cascade. Both testosterone and LH have been shown to modulate CNS Aβ accumulation in animal studies, and associations with cerebral amyloid load in human studies have supported this. The underlying mechanisms by which these hormones modulate Aβ accumulation and contribute to neurodegeneration are not completely understood, however they have been shown to regulate Aβ metabolism, enhance its clearance and alter the processing of its parent molecule, the amyloid precursor protein. This review will discuss underlying mechanisms by which testosterone and LH modulate Aβ and provide an update on therapeutic approaches targeting these hormones.
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Affiliation(s)
- Giuseppe Verdile
- School of Biomedical Sciences, CHIRI Biosciences, Curtin University, Bentley, Western Australia 6102, Australia; Centre of Excellence for Alzheimer's Disease Research and Care, School of Medical Sciences, Edith Cowan University, Joondalup, Western Australia 6027, Australia; Sir James McCusker Alzheimer's disease Research Unit, School of Psychiatry and Clinical Neurosciences, University of Western Australia, Crawley, Western Australia 6009, Australia.
| | - Prita R Asih
- Centre of Excellence for Alzheimer's Disease Research and Care, School of Medical Sciences, Edith Cowan University, Joondalup, Western Australia 6027, Australia; Dementia Research Unit, Department of Anatomy, School of Medical Sciences, Faculty of Medicine, University of NSW, Kensington, NSW 2052, Australia
| | - Anna M Barron
- National Institute of Radiological Sciences, Chiba-shi, Chiba 263-8555, Japan
| | - Eka J Wahjoepramono
- Sir James McCusker Alzheimer's disease Research Unit, School of Psychiatry and Clinical Neurosciences, University of Western Australia, Crawley, Western Australia 6009, Australia; Medical Faculty, Pelita Harapan University - Neuroscience Centre, Siloam Hospital, Lippo Karawaci, Tangerang, Indonesia
| | - Lars M Ittner
- Dementia Research Unit, Department of Anatomy, School of Medical Sciences, Faculty of Medicine, University of NSW, Kensington, NSW 2052, Australia; Neuroscience Research Australia, Randwick, NSW 2036, Australia
| | - Ralph N Martins
- Centre of Excellence for Alzheimer's Disease Research and Care, School of Medical Sciences, Edith Cowan University, Joondalup, Western Australia 6027, Australia; Sir James McCusker Alzheimer's disease Research Unit, School of Psychiatry and Clinical Neurosciences, University of Western Australia, Crawley, Western Australia 6009, Australia; School of Biomedical Sciences, CHIRI Biosciences, Curtin University, Bentley, Western Australia 6102, Australia
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Phillips KA, Bales KL, Capitanio JP, Conley A, Czoty PW, ‘t Hart BA, Hopkins WD, Hu SL, Miller LA, Nader MA, Nathanielsz PW, Rogers J, Shively CA, Voytko ML. Why primate models matter. Am J Primatol 2014; 76:801-27. [PMID: 24723482 PMCID: PMC4145602 DOI: 10.1002/ajp.22281] [Citation(s) in RCA: 391] [Impact Index Per Article: 39.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Revised: 03/01/2014] [Accepted: 03/02/2014] [Indexed: 12/13/2022]
Abstract
Research involving nonhuman primates (NHPs) has played a vital role in many of the medical and scientific advances of the past century. NHPs are used because of their similarity to humans in physiology, neuroanatomy, reproduction, development, cognition, and social complexity-yet it is these very similarities that make the use of NHPs in biomedical research a considered decision. As primate researchers, we feel an obligation and responsibility to present the facts concerning why primates are used in various areas of biomedical research. Recent decisions in the United States, including the phasing out of chimpanzees in research by the National Institutes of Health and the pending closure of the New England Primate Research Center, illustrate to us the critical importance of conveying why continued research with primates is needed. Here, we review key areas in biomedicine where primate models have been, and continue to be, essential for advancing fundamental knowledge in biomedical and biological research.
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Affiliation(s)
- Kimberley A. Phillips
- Department of Psychology, Trinity University, San Antonio TX 78212
- Southwest National Primate Research Center, Texas Biomedical Research Institute, San Antonio TX
| | - Karen L. Bales
- Department of Psychology, University of California, Davis CA 95616
- California National Primate Research Center, Davis CA 95616
| | - John P. Capitanio
- Department of Psychology, University of California, Davis CA 95616
- California National Primate Research Center, Davis CA 95616
| | - Alan Conley
- Department of Population Health & Reproduction, School of Veterinary Medicine, University of California, Davis CA 95616
| | - Paul W. Czoty
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem NC 27157
| | - Bert A. ‘t Hart
- Department of Immunobiology, Biomedical Primate Research Center, Rijswick, The Netherlands
| | - William D. Hopkins
- Neuroscience Institute and Language Research Center, Georgia State University, Atlanta GA 30302
- Division of Cognitive and Developmental Neuroscience, Yerkes National Primate Research Center, Atlanta GA 30030
| | - Shiu-Lok Hu
- Department of Pharmaceutics and Washington National Primate Research Center, University of Washington, Seattle WA
| | - Lisa A. Miller
- California National Primate Research Center, Davis CA 95616
- Department of Anatomy, Physiology and Cell Biology, University of California, Davis CA 95616
| | - Michael A. Nader
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem NC 27157
| | - Peter W. Nathanielsz
- Center for Pregnancy and Newborn Research, University of Texas Health Science Center, San Antonio TX 78229
| | - Jeffrey Rogers
- Human Genome Sequencing Center, Baylor College of Medicine, Houston TX
- Wisconsin National Primate Research Center, Madison, WI
| | - Carol A. Shively
- Department of Pathology, Section on Comparative Medicine, Wake Forest University School of Medicine, Winston-Salem NC 27157
| | - Mary Lou Voytko
- Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, Winston-Salem NC 27157
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Kermath BA, Riha PD, Woller MJ, Wolfe A, Gore AC. Hypothalamic molecular changes underlying natural reproductive senescence in the female rat. Endocrinology 2014; 155:3597-609. [PMID: 24914937 PMCID: PMC4138577 DOI: 10.1210/en.2014-1017] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The role of the hypothalamus in female reproductive senescence is unclear. Here we identified novel molecular neuroendocrine changes during the natural progression from regular reproductive cycles to acyclicity in middle-aged female rats, comparable with the perimenopausal progression in women. Expression of 48 neuroendocrine genes was quantified within three hypothalamic regions: the anteroventral periventricular nucleus, the site of steroid positive feedback onto GnRH neurons; the arcuate nucleus (ARC), the site of negative feedback and pulsatile GnRH release; and the median eminence (ME), the site of GnRH secretion. Surprisingly, the majority of changes occurred in the ARC and ME, with few effects in anteroventral periventricular nucleus. The overall pattern was increased mRNA levels with chronological age and decreases with reproductive cycle status in middle-aged rats. Affected genes included transcription factors (Stat5b, Arnt, Ahr), sex steroid hormone receptors (Esr1, Esr2, Pgr, Ar), steroidogenic enzymes (Sts, Hsd17b8), growth factors (Igf1, Tgfa), and neuropeptides (Kiss1, Tac2, Gnrh1). Bionetwork analysis revealed region-specific correlations between genes and hormones. Immunohistochemical analyses of kisspeptin and estrogen receptor-α in the ARC demonstrated age-related decreases in kisspeptin cell numbers as well as kisspeptin-estrogen receptor-α dual-labeled cells. Taken together, these results identify unexpectedly strong roles for the ME and ARC during reproductive decline and highlight fundamental differences between middle-aged rats with regular cycles and all other groups. Our data provide evidence of decreased excitatory stimulation and altered hormone feedback with aging and suggest novel neuroendocrine pathways that warrant future study. Furthermore, these changes may impact other neuroendocrine systems that undergo functional declines with age.
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Affiliation(s)
- Bailey A Kermath
- Institute for Neuroscience (B.A.K., A.C.G.), Division of Pharmacology and Toxicology (P.D.R., A.C.G.), and Institute for Cell and Molecular Biology (A.C.G.), The University of Texas at Austin, Austin, Texas 78712; Department of Biology (M.J.W.), University of Wisconsin-Whitewater, Whitewater, Wisconsin 53190; and Department of Pediatrics (A.W.), Johns Hopkins University School of Medicine, Baltimore Maryland 21287
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16
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Naugle MM, Nguyen LT, Merceron TK, Filardo E, Janssen WGM, Morrison JH, Rapp PR, Gore AC. G-protein coupled estrogen receptor, estrogen receptor α, and progesterone receptor immunohistochemistry in the hypothalamus of aging female rhesus macaques given long-term estradiol treatment. ACTA ACUST UNITED AC 2014; 321:399-414. [PMID: 24862737 DOI: 10.1002/jez.1871] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 04/28/2014] [Indexed: 12/15/2022]
Abstract
Steroid hormone receptors are widely and heterogeneously expressed in the brain, and are regulated by age and gonadal hormones. Our goal was to quantify effects of aging, long-term estradiol (E2 ) treatment, and their interactions, on expression of G protein-coupled estrogen receptor (GPER), estrogen receptor α (ERα) and progesterone receptor (PR) immunoreactivity in two hypothalamic regions, the arcuate (ARC) and the periventricular area (PERI) of rhesus monkeys as a model of menopause and hormone replacement. Ovariectomized (OVX) rhesus macaques were young (∼ 11 years) or aged (∼ 25 years), given oil (vehicle) or E2 every 3 weeks for 2 years. Immunohistochemistry and stereologic analysis of ERα, PR, and GPER was performed. More effects were detected for GPER than the other two receptors. Specifically, GPER cell density in the ARC and PERI, and the percent of GPER-immunoreactive cells in the PERI, were greater in aged than in young monkeys. In addition, we mapped the qualitative distribution of GPER in the monkey hypothalamus and nearby regions. For ERα, E2 treated monkeys tended to have higher cell density than vehicle monkeys in the ARC. The percent of PR density in the PERI tended to be higher in E2 than vehicle monkeys of both ages. This study shows that the aged hypothalamus maintains expression of hormone receptors with age, and that long-term cyclic E2 treatment has few effects on their expression, although GPER was affected more than ERα or PR. This result is surprising in light of evidence for E2 regulation of the receptors studied here, and differences may be due to the selected regions, long-term nature of E2 treatment, among other possibilities.
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Affiliation(s)
- Michelle M Naugle
- Institute for Neuroscience, University of Texas at Austin, Austin, Texas
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Naugle MM, Gore AC. GnRH neurons of young and aged female rhesus monkeys co-express GPER but are unaffected by long-term hormone replacement. Neuroendocrinology 2014; 100:334-46. [PMID: 25428637 PMCID: PMC4329056 DOI: 10.1159/000369820] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 11/05/2014] [Indexed: 12/18/2022]
Abstract
Menopause is caused by changes in the function of the hypothalamic-pituitary-gonadal axis that controls reproduction. Hypophysiotropic gonadotropin-releasing hormone (GnRH) neurons in the hypothalamus orchestrate the activity of this axis and are regulated by hormonal feedback loops. The mechanisms by which GnRH responds to the primary regulatory sex steroid hormone, estradiol (E2), are still poorly understood in the context of menopause. Our goal was to determine whether the G protein-coupled estrogen receptor (GPER) is co-expressed in adult primate GnRH neurons and whether this changes with aging and/or E2 treatment. We used immunofluorescence double-labeling to characterize the co-expression of GPER in GnRH perikarya and terminals in the hypothalamus. Young and aged rhesus macaques were ovariectomized and given long-term (~2-year) hormone treatments (E2, E2 + progesterone, or vehicle) selected to mimic currently prescribed hormone replacement therapies used for the alleviation of menopausal symptoms in women. We found that about half of GnRH perikarya co-expressed GPER, while only about 12% of GnRH processes and terminals in the median eminence (ME) were double-labeled. Additionally, many GPER-labeled processes were in direct contact with GnRH neurons, often wrapped around the perikarya and processes and in close proximity in the ME. These results extend prior work by showing robust co-localization of GPER in GnRH in a clinically relevant model, and they support the possibility that GPER-mediated E2 regulation of GnRH occurs both in the soma and terminals in nonhuman primates.
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Affiliation(s)
- Michelle M. Naugle
- Institute for Neuroscience, University of Texas at Austin, Austin, TX, 78712
| | - Andrea C. Gore
- Institute for Neuroscience, University of Texas at Austin, Austin, TX, 78712
- Pharmacology & Toxicology, College of Pharmacy, University of Texas at Austin, Austin, TX, 78712
- Institute for Cellular & Molecular Biology, University of Texas at Austin, Austin, TX, 78712
- Correspondence: Andrea C Gore, PhD, The University of Texas at Austin, 107 West Dean Keeton, C0875, Austin, TX, 78712, USA, ; Tel: +1-512-471-3669; Fax: +1-512-471-5002
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18
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Dehydroepiandrosterone sulfate levels reflect endogenous luteinizing hormone production and response to human chorionic gonadotropin challenge in older female macaque (Macaca fascicularis). Menopause 2013; 20:329-35. [PMID: 23435031 DOI: 10.1097/gme.0b013e3182698f80] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE We propose that the adrenal gland of an older higher primate female animal model will respond to human chorionic gonadotropin (hCG) hormone challenge by secreting additional dehydroepiandrosterone sulfate (DHEAS). Such a response in surgically and chemically castrated animals will provide proof of concept and a validated animal model for future studies to explore the rise in DHEAS during the menopausal transition of women. METHODS Twenty-four 18- to 26-year-old female cynomolgus monkeys were screened for ovarian function and then either ovariectomized (n = 4) or treated with a gonadotropin-releasing hormone agonist (GnRHa; n = 20) to block ovarian steroid production. After a recovery period from surgical procedure or down-regulation, a single-dose challenge (1,000 IU/animal, IM) of hCG was then administered to determine if luteinizing hormone (LH)/chorionic gonadotropin could accelerate circulating DHEAS production. Serum DHEAS, bioactive LH, and urinary metabolites of ovarian sex steroids were monitored before, during, and after these treatments. RESULTS Circulating LH bioactivity and immunoreactive DHEAS concentrations were suppressed in all animals 14 days postadministration of GnRHa. Urinary metabolites of estradiol and progesterone remained low after the surgical procedure or a flare reaction to GnRHa. Circulating DHEAS levels were increased after hCG administration, and the increase in individual animals was proportional to the pretreatment DHEAS at baseline. Circulating DHEAS concentrations were positively correlated to endogenous LH bioactive concentrations prior to hCG challenge and were subsequently further elevated by the hCG challenge while no concomitant change in ovarian steroid hormone excretion was observed. CONCLUSIONS These data demonstrate a positive adrenal androgen response to LH/chorionic gonadotropin in older female higher primates and suggest a mechanism for the rise in adrenal androgen production during the menopausal transition in women. These results also illustrate that the nonhuman primate animal model can be effectively used to investigate this phenomenon.
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19
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Rance NE, Dacks PA, Mittelman-Smith MA, Romanovsky AA, Krajewski-Hall SJ. Modulation of body temperature and LH secretion by hypothalamic KNDy (kisspeptin, neurokinin B and dynorphin) neurons: a novel hypothesis on the mechanism of hot flushes. Front Neuroendocrinol 2013; 34:211-27. [PMID: 23872331 PMCID: PMC3833827 DOI: 10.1016/j.yfrne.2013.07.003] [Citation(s) in RCA: 201] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Revised: 07/09/2013] [Accepted: 07/12/2013] [Indexed: 12/31/2022]
Abstract
Despite affecting millions of individuals, the etiology of hot flushes remains unknown. Here we review the physiology of hot flushes, CNS pathways regulating heat-dissipation effectors, and effects of estrogen on thermoregulation in animal models. Based on the marked changes in hypothalamic kisspeptin, neurokinin B and dynorphin (KNDy) neurons in postmenopausal women, we hypothesize that KNDy neurons play a role in the mechanism of flushes. In the rat, KNDy neurons project to preoptic thermoregulatory areas that express the neurokinin 3 receptor (NK3R), the primary receptor for NKB. Furthermore, activation of NK₃R in the median preoptic nucleus, part of the heat-defense pathway, reduces body temperature. Finally, ablation of KNDy neurons reduces cutaneous vasodilatation and partially blocks the effects of estrogen on thermoregulation. These data suggest that arcuate KNDy neurons relay estrogen signals to preoptic structures regulating heat-dissipation effectors, supporting the hypothesis that KNDy neurons participate in the generation of flushes.
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Affiliation(s)
- Naomi E Rance
- Department of Pathology and the Evelyn F. McKnight Brain Research Institute, University of Arizona College of Medicine, Tucson, AZ 85724, USA.
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20
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Franceschini I, Desroziers E. Development and Aging of the Kisspeptin-GPR54 System in the Mammalian Brain: What are the Impacts on Female Reproductive Function? Front Endocrinol (Lausanne) 2013; 4:22. [PMID: 23543285 PMCID: PMC3610010 DOI: 10.3389/fendo.2013.00022] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Accepted: 02/22/2013] [Indexed: 11/13/2022] Open
Abstract
The prominent role of the G protein coupled receptor GPR54 and its peptide ligand kisspeptin in the progression of puberty has been extensively documented in many mammalian species including humans. Kisspeptins are very potent gonadotropin-releasing hormone secretagogues produced by two main populations of neurons located in two ventral forebrain regions, the preoptic area and the arcuate nucleus. Within the last 2 years a substantial amount of data has accumulated concerning the development of these neuronal populations and their timely regulation by central and peripheral factors during fetal, neonatal, and peripubertal stages of development. This review focuses on the development of the kisspeptin-GPR54 system in the brain of female mice, rats, sheep, monkeys, and humans. We will also discuss the notion that this system represents a major target through which signals from the environment early in life can reprogram reproductive function.
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Affiliation(s)
- Isabelle Franceschini
- UMR85 Physiologie de la Reproduction et des Comportements, Institut National de Recherche AgronomiqueNouzilly, France
- UMR7247, Centre National de la Recherche ScientifiqueNouzilly, France
- Université François Rabelais de ToursTours, France
- Institut Français du Cheval et de l’EquitationNouzilly, France
- *Correspondence: Isabelle Franceschini, Centre INRA de Tours, Unité de Physiologie de la Reproduction et des Comportements, UMR 7247 INRA/CNRS/Univ. Tours/IFCE, 37380 Nouzilly, France. e-mail:
| | - Elodie Desroziers
- UMR85 Physiologie de la Reproduction et des Comportements, Institut National de Recherche AgronomiqueNouzilly, France
- UMR7247, Centre National de la Recherche ScientifiqueNouzilly, France
- Université François Rabelais de ToursTours, France
- Institut Français du Cheval et de l’EquitationNouzilly, France
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Kermath BA, Gore AC. Neuroendocrine control of the transition to reproductive senescence: lessons learned from the female rodent model. Neuroendocrinology 2012; 96:1-12. [PMID: 22354218 PMCID: PMC3574559 DOI: 10.1159/000335994] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Accepted: 12/06/2011] [Indexed: 01/19/2023]
Abstract
The natural transition to reproductive senescence is an important physiological process that occurs with aging, resulting in menopause in women and diminished or lost fertility in most mammalian species. This review focuses on how rodent models have informed our knowledge of age-related changes in gonadotropin-releasing hormone (GnRH) neurosecretory function and the subsequent loss of reproductive capacity. Studies in rats and mice have shown molecular, morphological and functional changes in GnRH cells. Furthermore, during reproductive aging altered sex steroid feedback to the hypothalamus contributes to a decrease of stimulatory signaling and increase in inhibitory tone onto GnRH neurons. At the site of the GnRH terminals where the peptide is released into the portal vasculature, the cytoarchitecture of the median eminence becomes disorganized with aging, and mechanisms of glial-GnRH neuronal communication may be disrupted. These changes can result in the dysregulation of GnRH secretion with reproductive decline. Interestingly, reproductive aging effects on the GnRH circuitry are observed in middle age even prior to any obvious physiological changes in cyclicity. We speculate that the hypothalamus may play a critical role in this mid-life transition. Because there are substantial species differences in these aging processes, we also compare and contrast rodent aging to that in primates. Work discussed herein shows that in order to understand neuroendocrine mechanisms of reproductive senescence, further research needs to be conducted in ovarian-intact models.
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Affiliation(s)
- Bailey A. Kermath
- Institute for Neurosciences; The University of Texas at Austin, Austin, TX, 78712, USA
| | - Andrea C. Gore
- Institute for Neurosciences; The University of Texas at Austin, Austin, TX, 78712, USA
- Division of Pharmacology & Toxicology; The University of Texas at Austin, Austin, TX, 78712, USA
- Institute for Cellular & Molecular Biology; The University of Texas at Austin, Austin, TX, 78712, USA
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Navarro VM. New insights into the control of pulsatile GnRH release: the role of Kiss1/neurokinin B neurons. Front Endocrinol (Lausanne) 2012; 3:48. [PMID: 22649420 PMCID: PMC3355984 DOI: 10.3389/fendo.2012.00048] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Accepted: 03/12/2012] [Indexed: 11/24/2022] Open
Abstract
Gonadotropin-releasing hormone (GnRH) is the ultimate output signal of an intricate network of neuroendocrine factors that, acting on the pituitary, trigger gonadotropin release. In turn, gonadotropins exert their trophic action on the gonads to stimulate the synthesis of sex steroids thus completing the gonadotropic axis through feedback regulatory mechanisms of GnRH release. These feedback loops are predominantly inhibitory in both sexes, leading to tonic pulsatile release of GnRH from puberty onward. However, in the female, rising levels of estradiol along the estrous cycle evoke an additional positive feedback that prompts a surge-like pattern of GnRH release prior to ovulation. Kisspeptins, secreted from hypothalamic Kiss1 neurons, are poised as major conduits to regulate this dual secretory pathway. Kiss1 neurons are diverse in origin, nature, and function, convening distinct neuronal populations in two main hypothalamic nuclei: the arcuate nucleus (ARC) and the anteroventral periventricular nucleus. Recent studies from our group and others point out Kiss1 neurons in the ARC as the plausible generator of GnRH pulses through a system of pulsatile kisspeptin release shaped by the coordinated action of neurokinin B (NKB) and dynorphin A (Dyn) that are co-expressed in Kiss1 neurons (so-called KNDy neurons). In this review, we aim to document the recent findings and working models directed toward the identification of the Kiss1-dependent mechanisms of GnRH release through a synoptic overview of the state-of-the-art in the field.
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Affiliation(s)
- Víctor M Navarro
- Department of Cell Biology, Physiology and Immunology, University of Córdoba Córdoba, Spain.
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Keenan DM, Clarke IJ, Veldhuis JD. Noninvasive analytical estimation of endogenous GnRH drive: analysis using graded competitive GnRH-receptor antagonism and a calibrating pulse of exogenous GnRH. Endocrinology 2011; 152:4882-93. [PMID: 22028450 PMCID: PMC3230048 DOI: 10.1210/en.2011-1461] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Homeostatic control of endocrine systems proceeds via feedforward (agonistic, stimulatory) and feedback (antagonistic, inhibitory) interactions mediated via implicit dose-response functions. However, neither the feedback/feedforward pathways nor the dose-response interfaces are directly observed in vivo. Thus, the goal was to formulate and estimate an ensemble construct of time-varying feedback/feedforward interactions among GnRH, LH, and testosterone (T) in the male gonadal axis. The new analytical model revises and extends an earlier construct by: 1) allowing systemic T concentrations to inhibit hypothalamic GnRH output; 2) estimating GnRH outflow after injection of a calibrating pulse of biosynthetic GnRH; 3) framing the pituitary response to GnRH as a secretory burst, rather than continuous LH release; and 4) regressing feedback and feedforward ensemble parameters on age, rather than evaluating age dichotomously. Application of this methodology in 21 men aged 23-72 yr unveiled age-related 1) diminution of GnRH efficacy normalized for the decline in free T with age (P = 0.016), 2) potentiation of maximal T feedback onto (inhibition of) GnRH secretion (P = 0.006), and 3) accentuation of hypothalamic GnRH's sensitivity to T repression (P = 0.003). Outcomes were specific, because injected GnRH agonist and antagonist concentrations were invariant of age. We conclude that combining experimental and analytical strategies may provide a noninvasive means to investigate and decipher feedback determinants of unobserved endocrine signal(s).
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Affiliation(s)
- Daniel M Keenan
- Department of Statistics, University of Virginia, Charlottesville, Virginia 22904, USA
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Gore AC, Walker DM, Zama AM, Armenti AE, Uzumcu M. Early life exposure to endocrine-disrupting chemicals causes lifelong molecular reprogramming of the hypothalamus and premature reproductive aging. Mol Endocrinol 2011; 25:2157-68. [PMID: 22016562 DOI: 10.1210/me.2011-1210] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Gestational exposure to the estrogenic endocrine disruptor methoxychlor (MXC) disrupts the female reproductive system at the molecular, physiological, and behavioral levels in adulthood. The current study addressed whether perinatal exposure to endocrine disruptors re-programs expression of a suite of genes expressed in the hypothalamus that control reproductive function and related these molecular changes to premature reproductive aging. Fischer rats were exposed daily for 12 consecutive days to vehicle (dimethylsulfoxide), estradiol benzoate (EB) (1 mg/kg), and MXC (low dose, 20 μg/kg or high dose, 100 mg/kg), beginning on embryonic d 19 through postnatal d 7. The perinatally exposed females were aged to 16-17 months and monitored for reproductive senescence. After euthanasia, hypothalamic regions [preoptic area (POA) and medial basal hypothalamus] were dissected for real-time PCR of gene expression or pyrosequencing to assess DNA methylation of the Esr1 gene. Using a 48-gene PCR platform, two genes (Kiss1 and Esr1) were significantly different in the POA of endocrine-disrupting chemical-exposed rats compared with vehicle-exposed rats after Bonferroni correction. Fifteen POA genes were up-regulated by at least 50% in EB or high-dose MXC compared with vehicle. To understand the epigenetic basis of the increased Esr1 gene expression, we performed bisulfite conversion and pyrosequencing of the Esr1 promoter. EB-treated rats had significantly higher percentage of methylation at three CpG sites in the Esr1 promoter compared with control rats. Together with these molecular effects, perinatal MXC and EB altered estrous cyclicity and advanced reproductive senescence. Thus, early life exposure to endocrine disruptors has lifelong effects on neuroendocrine gene expression and DNA methylation, together with causing the advancement of reproductive senescence.
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Affiliation(s)
- Andrea C Gore
- Institute for Neuroscience, The University of Texas at Austin, Austin, Texas 78712, USA.
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Boulware MI, Kent BA, Frick KM. The impact of age-related ovarian hormone loss on cognitive and neural function. Curr Top Behav Neurosci 2011; 10:165-84. [PMID: 21533680 DOI: 10.1007/7854_2011_122] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
On average, women now live one-third of their lives after menopause. Because menopause has been associated with an elevated risk of dementia, an increasing body of research has studied the effects of reproductive senescence on cognitive function. Compelling evidence from humans, nonhuman primates, and rodents suggests that ovarian sex-steroid hormones can have rapid and profound effects on memory, attention, and executive function, and on regions of the brain that mediate these processes, such as the hippocampus and prefrontal cortex. This chapter will provide an overview of studies in humans, nonhuman primates, and rodents that examine the effects of ovarian hormone loss and hormone replacement on cognitive functions mediated by the hippocampus and prefrontal cortex. For humans and each animal model, we outline the effects of aging on reproductive function, describe how ovarian hormones (primarily estrogens) modulate hippocampal and prefrontal physiology, and discuss the effects of both reproductive aging and hormone treatment on cognitive function. Although this review will show that much has been learned about the effects of reproductive senescence on cognition, many critical questions remain for future investigation.
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Affiliation(s)
- Marissa I Boulware
- Department of Psychology, University of Wisconsin-Milwaukee, 2441 E. Hartford Ave, Milwaukee, WI 53211, USA
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Peng J, Xu H, Yang B, Hu J, Zhang BP, Zou L, Kuang HB. Plasma levels of kisspeptins in postmenopausal Chinese women do not show substantial elevation. Peptides 2010; 31:2255-8. [PMID: 20833219 DOI: 10.1016/j.peptides.2010.09.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Revised: 09/01/2010] [Accepted: 09/01/2010] [Indexed: 10/19/2022]
Abstract
The menopause, defined as the permanent cessation of menstruation resulting from ovarian failure, is characterized by elevated levels of serum gonadotropins. Recent studies have demonstrated that the gonadotropin hypersecretion in postmenopausal women is secondary to increase of KiSS-1 mRNA from the hypothalamus neurons, which encoded kisspeptin peptides. The present study was designed to determine whether plasma kisspeptins levels are altered in postmenopausal women. Blood samples were taken from 145 postmenopausal women, 35 young women and 30 pregnant women control in the first trimester. The plasma concentration of kisspeptins, follicle-stimulating hormone (FSH), luteinizing hormone (LH) and estradiol (E₂) was measured using immunoassay kits. Results indicated that plasma kisspeptins levels in postmenopausal women had higher than those in young women (5.25±0.36; 4.48±0.34 pmol/L), but no significant difference was found between the two groups (p=0.179). Plasma FSH and LH levels were significantly higher in postmenopausal women (124.67±12.78, 57.14±3.57 mIu/mL) than those in young women (9.23±2.78, 7.56±2.71 mIu/mL, p<0.001). However, Plasma kisspeptins levels were not significantly correlated to FSH and LH in postmenopausal women (r=-0.23, 0.324; p=0.927, 0.176, respectively), and also there was no any correlation between plasma kisspeptins and E₂ in postmenopausal women (r=-0.065; p=0.792). Collectively, there was no significant difference in plasma kisspeptins levels between postmenopausal and young women. Our result suggested that kisspeptins' role during menopause might mainly act in central rather than peripheral system and it could not be currently used as a clinical marker for menopause.
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Affiliation(s)
- Jing Peng
- Department of Physiology, School of Medicine, Nanchang University, Nanchang, Jiangxi, China
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Wang L, Chadwick W, Park SS, Zhou Y, Silver N, Martin B, Maudsley S. Gonadotropin-releasing hormone receptor system: modulatory role in aging and neurodegeneration. CNS & NEUROLOGICAL DISORDERS DRUG TARGETS 2010; 9:651-60. [PMID: 20632963 PMCID: PMC2967575 DOI: 10.2174/187152710793361559] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2010] [Accepted: 02/25/2010] [Indexed: 12/15/2022]
Abstract
Receptors for hormones of the hypothalamic-pituitary-gonadal axis are expressed throughout the brain. Age-related decline in gonadal reproductive hormones cause imbalances of this axis and many hormones in this axis have been functionally linked to neurodegenerative pathophysiology. Gonadotropin-releasing hormone (GnRH) plays a vital role in both central and peripheral reproductive regulation. GnRH has historically been known as a pituitary hormone; however, in the past few years, interest has been raised in GnRH actions at non-pituitary peripheral targets. GnRH ligands and receptors are found throughout the brain where they may act to control multiple higher functions such as learning and memory function and feeding behavior. The actions of GnRH in mammals are mediated by the activation of a unique rhodopsin-like G protein-coupled receptor that does not possess a cytoplasmic carboxyl terminal sequence. Activation of this receptor appears to mediate a wide variety of signaling mechanisms that show diversity in different tissues. Epidemiological support for a role of GnRH in central functions is evidenced by a reduction in neurodegenerative disease after GnRH agonist therapy. It has previously been considered that these effects were not via direct GnRH action in the brain, however recent data has pointed to a direct central action of these ligands outside the pituitary. We have therefore summarized the evidence supporting a central direct role of GnRH ligands and receptors in controlling central nervous physiology and pathophysiology.
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Affiliation(s)
- Liyun Wang
- Receptor Pharmacology Unit, National Institute on Aging, National Institutes of Health, Biomedical Research Center, 251 Bayview Boulevard, Baltimore MD 21224
| | - Wayne Chadwick
- Receptor Pharmacology Unit, National Institute on Aging, National Institutes of Health, Biomedical Research Center, 251 Bayview Boulevard, Baltimore MD 21224
| | - Soo-Sung Park
- Receptor Pharmacology Unit, National Institute on Aging, National Institutes of Health, Biomedical Research Center, 251 Bayview Boulevard, Baltimore MD 21224
| | - Yu Zhou
- Receptor Pharmacology Unit, National Institute on Aging, National Institutes of Health, Biomedical Research Center, 251 Bayview Boulevard, Baltimore MD 21224
| | - Nathan Silver
- Receptor Pharmacology Unit, National Institute on Aging, National Institutes of Health, Biomedical Research Center, 251 Bayview Boulevard, Baltimore MD 21224
| | - Bronwen Martin
- Metabolism Unit, Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Biomedical Research Center, 251 Bayview Boulevard, Baltimore MD 21224
| | - Stuart Maudsley
- Receptor Pharmacology Unit, National Institute on Aging, National Institutes of Health, Biomedical Research Center, 251 Bayview Boulevard, Baltimore MD 21224
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Abstract
The median eminence at the base of the hypothalamus serves as an interface between the neural and peripheral endocrine systems. It releases hypothalamic-releasing hormones into the portal capillary bed for transport to the anterior pituitary, which provides further signals to target endocrine systems. Of specific relevance to reproduction, a group of about 1000 neurons in mammals release the gonadotropin-releasing hormone (GnRH) peptide from neuroterminals in the median eminence. During the life cycle, there are dramatic changes in reproductive demands, and we focus this review on how GnRH terminals in the median eminence change during reproductive senescence. We discuss morphological and functional properties of the median eminence, and how relationships among GnRH terminals and their microenvironment of nerve terminals, glial cells, and the portal capillary vasculature determine the ability of GnRH peptide to be secreted and to reach its target in the anterior pituitary gland.
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Affiliation(s)
- Weiling Yin
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Austin, Texas 78712, USA
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Appt SE, Ethun KF. Reproductive aging and risk for chronic disease: Insights from studies of nonhuman primates. Maturitas 2010; 67:7-14. [PMID: 20430541 PMCID: PMC2941880 DOI: 10.1016/j.maturitas.2010.03.028] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Revised: 03/30/2010] [Accepted: 03/31/2010] [Indexed: 01/08/2023]
Abstract
Reproductive aging and ovarian senescence have considerable public health relevance because they are associated with increased risk for coronary heart disease (CHD), osteoporosis and other degenerative conditions including cognitive decline and potentially the metabolic syndrome. It has been suggested that the hormonal dysregulation that occurs during the perimenopausal transition may play a role in the initiation of pathobiological changes (e.g., adverse lipid profiles, atherosclerotic plaques) that will increase risk for chronic disease (e.g., CHD) during the postmenopausal years. Moreover, these early changes are suspected to establish a trajectory of disease progression that may be difficult to alter if interventions are not begun until after menopause. Even a slight increase in the rate of disease progression during the pre- or perimenopausal years could have substantial consequences for health and quality of life over the postmenopausal lifespan. Thus, the years leading up to menopause may offer a "critical window" for interventions aimed at reducing the postmenopausal disease burden. The relationship between perimenopausal hormonal dysregulation and the risk for chronic disease is poorly understood due, in large part, to the lack of appropriate animal models of the perimenopausal transition and natural menopause. In this review we assesses studies of nonhuman primates (NHPs) evaluated in various reproductive stages (naturally pre-, peri- and postmenopausal, surgically menopausal) and their contribution to our understanding about risk factors for chronic disease. Finally, because large numbers of naturally perimenopausal and menopausal NHPs are not available for research at present, experimental approaches that have the potential to hasten the onset of the perimenopausal transition will be described.
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Affiliation(s)
- Susan E Appt
- Wake Forest University School of Medicine, Department of Pathology (Comparative Medicine), Wake Forest University Primate Center, Winston-Salem, NC 27157-1040, USA.
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Rance NE, Krajewski SJ, Smith MA, Cholanian M, Dacks PA. Neurokinin B and the hypothalamic regulation of reproduction. Brain Res 2010; 1364:116-28. [PMID: 20800582 DOI: 10.1016/j.brainres.2010.08.059] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2010] [Revised: 08/17/2010] [Accepted: 08/19/2010] [Indexed: 10/19/2022]
Abstract
Loss-of-function mutations in the genes encoding either neurokinin B (NKB) or its receptor, NK3 (NK3R), result in hypogonadotropic hypogonadism, characterized by an absence of pubertal development and low circulating levels of LH and gonadal steroids. These studies implicate NKB and NK3R as essential elements of the human reproductive axis. Studies over the last two decades provide evidence that a group of neurons in the hypothalamic infundibular/arcuate nucleus form an important component of this regulatory circuit. These neurons are steroid-responsive and coexpress NKB, kisspeptin, dynorphin, NK3R, and estrogen receptor α (ERα) in a variety of mammalian species. Compelling evidence in the human indicates these neurons function in the hypothalamic circuitry regulating estrogen negative feedback on gonadotropin-releasing hormone (GnRH) secretion. Moreover, in the rat, they form a bilateral, interconnected network that projects to NK3R-expressing GnRH terminals in the median eminence. This network provides an anatomical framework to explain how coordination among NKB/kisspeptin/dynorphin/NK3R/ERα neurons could mediate feedback information from the gonads to modulate pulsatile GnRH secretion. There is substantial (but indirect) evidence that this network may be part of the neural circuitry known as the "GnRH pulse generator," with NK3R signaling as an important component. This theory provides a compelling explanation for the occurrence of hypogonadotropic hypogonadism in patients with inactivating mutations in the TAC3 or TACR3 genes. Future studies will be needed to determine whether NKB signaling plays a permissive role in the onset of puberty or is part of the driving force initiating the maturation of reproductive function.
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Affiliation(s)
- Naomi E Rance
- Department of Pathology, and the Evelyn F. McNight Brain Research Institute, University of Arizona College of Medicine, Tucson, AZ 85724, USA.
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Eghlidi DH, Haley GE, Noriega NC, Kohama SG, Urbanski HF. Influence of age and 17beta-estradiol on kisspeptin, neurokinin B, and prodynorphin gene expression in the arcuate-median eminence of female rhesus macaques. Endocrinology 2010; 151:3783-94. [PMID: 20519367 PMCID: PMC2940528 DOI: 10.1210/en.2010-0198] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Accepted: 05/06/2010] [Indexed: 11/19/2022]
Abstract
The neuropeptides kisspeptin, neurokinin B, and dynorphin A (collectively abbreviated as KNDy) are, respectively, encoded by KiSS-1, NKB, and PDYN and are coexpressed by neurons of the hypothalamic arcuate nucleus (ARC). Here, using quantitative real-time PCR, we examined age-related changes in the expression of genes encoding KNDy and associated receptors G protein-coupled receptor 54 (encoded by GPR54), neurokinin 3 receptor (encoded by NK3), and kappa-opioid receptor (encoded by KOR), in the female rhesus macaque ARC-median eminence (ARC-ME). Expression of KiSS-1 and NKB was highly elevated in old perimenopausal compared with young or middle-aged premenopausal animals. To test whether these age-related changes could be attributed to perimenopausal loss of sex steroids, we then examined KNDy, GPR54, NK3, and KOR expression changes in response to ovariectomy (OVX) and exposure to 17beta-estradiol (E(2)). Short-term (7 months) OVX (with or without 1 month of estrogen replacement) failed to modulate the expression of any of the KNDy-related genes. In contrast, long-term ( approximately 4 yr) OVX significantly increased KiSS-1 and NKB expression, and this was reversed by E(2) administration. Finally, we examined the expression of KNDy-related genes in young adult females during the early follicular, late follicular, or midluteal phases of their menstrual cycle but found no difference. Together, the results suggest that short-term alterations in circulating E(2) levels, such as those occurring during the menstrual cycle, may have little effect on the ARC-ME expression of KNDy and associated receptors. Nevertheless, they clearly demonstrate that loss of ovarian steroid negative feedback that occurs during perimenopause plays a major role in modulating the activity of KNDy circuits of the aging primate ARC-ME.
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Affiliation(s)
- Dominique H Eghlidi
- Division of Neuroscience, Oregon National Primate Research Center, Beaverton, Oregon 97006, USA
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Neal-Perry G, Nejat E, Dicken C. The neuroendocrine physiology of female reproductive aging: An update. Maturitas 2010; 67:34-8. [PMID: 20570066 DOI: 10.1016/j.maturitas.2010.04.016] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2010] [Revised: 04/24/2010] [Accepted: 04/26/2010] [Indexed: 11/16/2022]
Abstract
The transition into menopause is a complex process that affects fertility and increases the risk for a number of health problems in aging women that include, but are not limited to osteoporosis, heart disease, diabetes mellitus and cognitive dysfunction. Improved nutrition and enhanced access to medical care have increased the average lifespan for women in developed countries, and many will spend more than one-third of their life in a post-menopausal state. Epidemiological studies indicate that a delayed natural menopause confers longevity and decelerates the appearance of much age-related morbidity, suggesting that developing treatments to delay menopause would significantly improve quality of life for women. Although menopause is ultimately defined by ovarian follicular exhaustion, several lines of scientific evidence in humans and animals now suggest that dysregulation of estradiol feedback mechanisms and hypothalamic-pituitary dysfunction contributes to the onset and progression of reproductive senescence, independent of ovarian failure. This article provides a brief update on our current understanding of the role of the hypothalamic-pituitary axis in the onset of and transition into female reproductive senescence.
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Affiliation(s)
- Genevieve Neal-Perry
- Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, Montefiore Medical Center and Albert Einstein College of Medicine and Yeshiva University, Bronx, NY, USA.
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Age- and sex-specific changes in naloxone-induced luteinizing hormone secretion and Fos expression in gonadotropin-releasing hormone neurons of gonadectomized rats. Neurosci Lett 2010; 471:157-61. [DOI: 10.1016/j.neulet.2010.01.032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2009] [Revised: 12/29/2009] [Accepted: 01/15/2010] [Indexed: 11/23/2022]
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34
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Age-dependent changes in fecal 17beta-estradiol and progesterone concentrations in female spider monkeys (Ateles geoffroyi). Theriogenology 2010; 73:468-73. [PMID: 19963259 DOI: 10.1016/j.theriogenology.2009.09.029] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2009] [Revised: 09/22/2009] [Accepted: 09/29/2009] [Indexed: 11/20/2022]
Abstract
The objective of this study was to investigate whether sex steroids decreased with age in female black-handed spider monkeys (Ateles geoffroyi). Fecal concentrations of 17beta-estradiol and progesterone (five samples/wk) and the number of ovulatory and anovulatory cycles were compared between adult (n=3) and aged females (n=2). All animals (regardless of age) had higher 17beta-estradiol concentrations during the fertile than the nonfertile phases. However, during the fertile phase, concentrations of this hormone were significantly higher in adult females. Conversely, progesterone concentrations varied normally throughout the menstrual cycle in both adult and aged animals, with no significant difference between age classes. Similarly, there was no significant effect of age on the number of ovulatory and anovulatory cycles. In conclusion, we inferred that the aged female spider monkeys did not reach menopause, instead they remained in a perimenopausal period characterized by changes in fecal concentrations of ovarian steroids and hypothalamus-hypophysis-ovary axis activity, as well as irregular menstrual flows, for prolonged intervals.
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35
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Abstract
OBJECTIVE Menopausal hot flashes compromise the quality of life for most women. The physiological mechanisms underlying hot flashes remain poorly understood, and the absence of an animal model to investigate hot flashes hinders investigations in this field. METHODS We first developed the sheep as a model to study peripheral skin temperature changes using fever-inducing lipopolysaccharide (LPS; 200 microg/kg) administered to ovary-intact ewes. Because a strong correlation between luteinizing hormone pulses and hot flashes has previously been reported, we then determined whether intravenous gonadotropin-releasing hormone (GnRH; 1 mg), a dose sufficient to elevate cerebrospinal fluid-GnRH concentrations, could modulate ear skin temperature in both ovariectomized and low-estrogen-replaced ovariectomized ewes. RESULTS Some ewes responded to LPS in heart rate and abdominal temperature, but there was no significant effect on either parameter or cheek temperature for the group. In contrast, LPS injection caused a significant (P < 0.001) change in skin temperature at the ear. Ear temperature showed no significant change in response to GnRH relative to control injections in both ovariectomized and low estrogen ewes. CONCLUSIONS We developed a model animal system in the ewe that can accurately detect small changes in peripheral skin temperature. This system has the potential to be extremely useful in future studies investigating the pathology of hot flashes and holds several advantages over previous model systems developed for this research. GnRH per se does not seem to be involved in thermoregulatory events.
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36
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Williams WP, Gibson EM, Wang C, Tjho S, Khattar N, Bentley GE, Tsutsui K, Kriegsfeld LJ. Proximate mechanisms driving circadian control of neuroendocrine function: Lessons from the young and old. Integr Comp Biol 2009; 49:519-37. [PMID: 21665838 PMCID: PMC7190900 DOI: 10.1093/icb/icp041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Circadian rhythms impact a variety of behavioral and physiological functions contributing to longevity and successful reproduction. In their natural environments, individuals of a species are faced with a multitude of challenges and the coordination of internal processes and behavior with external pressures has been hypothesized to be an important target of natural selection. Several lines of evidence from cyanobacteria, Drosophila, and plants provide strong support for an important role of the circadian clock in survival and reproductive success. Similarly in mammals, disruptions in circadian function markedly impact reproduction and lifespan. The present review discusses research outlining the proximate and ultimate mechanisms responsible for the central and peripheral control of the reproductive axis. Because precise temporal coordination of the endocrine system is particularly crucial for reproduction by females, the present overview focuses on the role of circadian timing in this sex.
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Affiliation(s)
- Wilbur P Williams
- *Department of Psychology, University of California, Berkeley, CA;Department of Integrative Biology, University of California, Berkeley, CA, 94720 USA;Helen Wills Neuroscience Institute, University of California, Berkeley, CA, 94720 USA;Laboratory of Integrative Brain Sciences, Department of Biology, Waseda University, Tokyo 162-8480, Japan
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37
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Meethal SV, Liu T, Chan HW, Ginsburg E, Wilson AC, Gray DN, Bowen RL, Vonderhaar BK, Atwood CS. Identification of a regulatory loop for the synthesis of neurosteroids: a steroidogenic acute regulatory protein-dependent mechanism involving hypothalamic-pituitary-gonadal axis receptors. J Neurochem 2009; 110:1014-27. [PMID: 19493163 DOI: 10.1111/j.1471-4159.2009.06192.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Brain sex steroids are derived from both peripheral (primarily gonadal) and local (neurosteroids) sources and are crucial for neurogenesis, neural differentiation and neural function. The mechanism(s) regulating the production of neurosteroids is not understood. To determine whether hypothalamic-pituitary-gonadal axis components previously detected in the extra-hypothalamic brain comprise a feedback loop to regulate neuro-sex steroid (NSS) production, we assessed dynamic changes in expression patterns of steroidogenic acute regulatory (StAR) protein, a key regulator of steroidogenesis, and key hypothalamic-pituitary-gonadal endocrine receptors, by modulating peripheral sex hormone levels in female mice. Ovariectomy (OVX; high serum gonadotropins, low serum sex steroids) had a differential effect on StAR protein levels in the extrahypothalamic brain; increasing the 30- and 32-kDa variants but decreasing the 37-kDa variant and is indicative of cholesterol transport into mitochondria for steroidogenesis. Treatment of OVX animals with E(2), P(4), or E(2) + P(4) for 3 days, which decreases OVX-induced increases in GnRH/gonadotropin production, reversed this pattern. Suppression of gonadotropin levels in OVX mice using the GnRH agonist leuprolide acetate inhibited the processing of the 37-kDa StAR protein into the 30-kDa StAR protein, confirming that the differential processing of brain StAR protein is regulated by gonadotropins. OVX dramatically suppressed extra-hypothalamic brain gonadotropin-releasing hormone 1 receptor expression, and was further suppressed in E(2)- or P(4)-treated OVX mice. Together, these data indicate the existence of endocrine and autocrine/paracrine feedback loops that regulate NSS synthesis. Further delineation of these feedback loops that regulate NSS production will aid in developing therapies to maintain brain sex steroid levels and cognition.
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Affiliation(s)
- Sivan Vadakkadath Meethal
- Department of Medicine, University of Wisconsin and Geriatric Research, Education and Clinical Center, Veterans Administration Hospital, Madison, Wisconsin 53705, USA
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Skinner DC, Albertson AJ, Navratil A, Smith A, Mignot M, Talbott H, Scanlan-Blake N. Effects of gonadotrophin-releasing hormone outside the hypothalamic-pituitary-reproductive axis. J Neuroendocrinol 2009; 21:282-92. [PMID: 19187469 PMCID: PMC2669307 DOI: 10.1111/j.1365-2826.2009.01842.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Gonadotrophin-releasing hormone (GnRH) is a hypothalamic decapeptide with an undisputed role as a primary regulator of gonadal function. It exerts this regulation by controlling the release of gonadotrophins. However, it is becoming apparent that GnRH may have a variety of other vital roles in normal physiology. A reconsideration of the potential widespread action that this traditional reproductive hormone exerts may lead to the generation of novel therapies and provide insight into seemingly incongruent outcomes from current treatments using GnRH analogues to combat diseases such as prostate cancer.
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Affiliation(s)
- D C Skinner
- Neurobiology Program and Department of Zoology and Physiology, University of Wyoming, Laramie, WY 82071, USA.
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Downs JL, Wise PM. The role of the brain in female reproductive aging. Mol Cell Endocrinol 2009; 299:32-8. [PMID: 19063938 PMCID: PMC2692385 DOI: 10.1016/j.mce.2008.11.012] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2008] [Revised: 11/08/2008] [Accepted: 11/12/2008] [Indexed: 11/19/2022]
Abstract
In middle-aged women, follicular depletion is a critical factor mediating the menopausal transition; however, all levels of the hypothalamic-pituitary-gonadal (HPG) axis contribute to the age-related decline in reproductive function. To help elucidate the complex interactions between the ovary and brain during middle-age that lead to the onset of the menopause, we utilize animal models which share striking similarities in reproductive physiology. Our results show that during middle-age, prior to any overt irregularities in estrous cyclicity, the ability of 17beta-estradiol (E(2)) to modulate the cascade of neurochemical events required for preovulatory gonadotropin-releasing hormone (GnRH) release and a luteinizing hormone (LH) surge is diminished. Middle-aged female rats experience a delay in and an attenuation of LH release in response to E(2). Additionally, although we do not observe a decrease in GnRH neuron number until a very advanced age, E(2)-mediated GnRH neuronal activation declines during the earliest stages of age-related reproductive decline. Numerous hypothalamic neuropeptides and neurochemical stimulatory inputs (i.e., glutamate, norepinephrine (NE), and vasoactive intestinal peptide (VIP)) that drive the E(2)-mediated GnRH/LH surge appear to dampen with age or lack the precise temporal coordination required for a specific pattern of GnRH secretion, while inhibitory signals such as gamma-aminobutyric acid (GABA) and opioid peptides remain unchanged or elevated during the afternoon of proestrus. These changes, occurring at the level of the hypothalamus, lead to irregular estrous cycles and, ultimately, the cessation of reproductive function. Taken together, our studies indicate that the hypothalamus is an important contributor to age-related female reproductive decline.
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Affiliation(s)
- Jodi L Downs
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA.
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40
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Maffucci JA, Gore AC. Chapter 2: hypothalamic neural systems controlling the female reproductive life cycle gonadotropin-releasing hormone, glutamate, and GABA. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2009; 274:69-127. [PMID: 19349036 DOI: 10.1016/s1937-6448(08)02002-9] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The hypothalamic-pituitary-gonadal (HPG) axis undergoes a number of changes throughout the reproductive life cycle that are responsible for the development, puberty, adulthood, and senescence of reproductive systems. This natural progression is dictated by the neural network controlling the hypothalamus including the cells that synthesize and release gonadotropin-releasing hormone (GnRH) and their regulatory neurotransmitters. Glutamate and GABA are the primary excitatory and inhibitory neurotransmitters in the central nervous system, and as such contribute a great deal to modulating this axis throughout the lifetime via their actions on receptors in the hypothalamus, both directly on GnRH neurons as well as indirectly through other hypothalamic neural networks. Interactions among GnRH neurons, glutamate, and GABA, including the regulation of GnRH gene and protein expression, hormone release, and modulation by estrogen, are critical to age-appropriate changes in reproductive function. Here, we present evidence for the modulation of GnRH neurosecretory cells by the balance of glutamate and GABA in the hypothalamus, and the functional consequences of these interactions on reproductive physiology across the life cycle.
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41
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Kim W, Jessen HM, Auger AP, Terasawa E. Postmenopausal increase in KiSS-1, GPR54, and luteinizing hormone releasing hormone (LHRH-1) mRNA in the basal hypothalamus of female rhesus monkeys. Peptides 2009; 30:103-10. [PMID: 18619506 PMCID: PMC2612733 DOI: 10.1016/j.peptides.2008.06.005] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/29/2008] [Revised: 06/10/2008] [Accepted: 06/12/2008] [Indexed: 10/21/2022]
Abstract
The G-protein coupled receptor, GPR54, and its ligand, kisspeptin-54 (a KiSS-1 derived peptide) have been reported to be important players in control of LHRH-1 release. However, the role of the GPR54 signaling in primate reproductive senescence is still unclear. In the present study we investigated whether KiSS-1, GPR54, and LHRH-1 mRNA in the brain change after menopause in female rhesus monkeys using quantitative real-time PCR. Results indicate that KiSS-1, GPR54, and LHRH-1 mRNA levels in the medial basal hypothalamus (MBH) in postmenopausal females (28.3+/-1.1 years of age, n=5) were all significantly higher than that in eugonadal adult females (14.7+/-2.1 years of age, n=9), whereas KiSS-1, GPR54, and LHRH-1 mRNA levels in the preoptic area (POA) did not have any significant changes between the two age groups. To further determine the potential contribution by the absence of ovarian steroids, we compared the changes in KiSS-1, GPR54, and LHRH-1 mRNA levels in young adult ovarian intact vs. young ovariectomized females. Results indicate that KiSS-1 and LHRH-1 mRNA levels in the MBH, not POA, in ovariectomized females were significantly higher than those in ovarian intact females, whereas GPR54 mRNA levels in ovariectomized females had a tendency to be elevated in the MBH, although the values were not quite statistically significant. Collectively, in the primate the reduction in the negative feedback control by ovarian steroids appears to be responsible for the aging changes in kisspeptin-GPR54 signaling and the elevated state of the LHRH-1 neuronal system.
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Affiliation(s)
- Wooram Kim
- Wisconsin National Primate Research Center, University of Wisconsin, 1223 Capitol Court, Madison, WI 53715-1299, USA
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42
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Rance NE. Menopause and the human hypothalamus: evidence for the role of kisspeptin/neurokinin B neurons in the regulation of estrogen negative feedback. Peptides 2009; 30:111-22. [PMID: 18614256 PMCID: PMC2632595 DOI: 10.1016/j.peptides.2008.05.016] [Citation(s) in RCA: 148] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/29/2008] [Revised: 05/01/2008] [Accepted: 05/05/2008] [Indexed: 10/22/2022]
Abstract
Menopause is characterized by depletion of ovarian follicles, a reduction of ovarian hormones to castrate levels and elevated levels of serum gonadotropins. Rather than degenerating, the reproductive neuroendocrine axis in postmenopausal women is intact and responds robustly to the removal of ovarian hormones. Studies in both human and non-human primates provide evidence that the gonadotropin hypersecretion in postmenopausal women is secondary to increased gonadotropin-releasing hormone (GnRH) secretion from the hypothalamus. In addition, menopause is accompanied by hypertrophy of neurons in the infundibular (arcuate) nucleus expressing KiSS-1, neurokinin B (NKB), substance P, dynorphin and estrogen receptor alpha (ERalpha) mRNA. Ovariectomy in experimental animals induces nearly identical findings, providing evidence that these changes are a compensatory response to ovarian failure. The anatomical site of the hypertrophied neurons, as well as the extensive data implicating kisspeptin, NKB and dynorphin in the regulation of GnRH secretion, provide compelling evidence that these neurons are part of the neural network responsible for the increased levels of serum gonadotropins in postmenopausal women. We propose that neurons expressing KiSS-1, NKB, substance P, dynorphin and ERalpha mRNA in the infundibular nucleus play an important role in sex-steroid feedback on gonadotropin secretion in the human.
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Affiliation(s)
- Naomi E Rance
- Departments of Pathology, Cell Biology and Anatomy and Neurology and the Evelyn F. McKnight Brain Institute, University of Arizona College of Medicine, 1501 N. Campbell Avenue, Tucson, AZ 85724, USA.
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Weinbauer GF, Niehoff M, Niehaus M, Srivastav S, Fuchs A, Van Esch E, Cline JM. Physiology and Endocrinology of the Ovarian Cycle in Macaques. Toxicol Pathol 2008; 36:7S-23S. [PMID: 20852722 PMCID: PMC2939751 DOI: 10.1177/0192623308327412] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Macaques provide excellent models for preclinical testing and safety assessment of female reproductive toxicants. Currently, cynomolgus monkeys are the predominant species for (reproductive) toxicity testing. Marmosets and rhesus monkeys are being used occasionally. The authors provide a brief review on physiology and endocrinology of the cynomolgus monkey ovarian cycle, practical guidance on assessment and monitoring of ovarian cyclicity, and new data on effects of social housing on ovarian cyclicity in toxicological studies. In macaques, cycle monitoring is achieved using daily vaginal smears for menstruation combined with cycle-timed frequent sampling for steroid and peptide hormone analysis. Owing to requirements of frequent and timed blood sampling, it is not recommended to incorporate these special evaluations into a general toxicity study design. Marmosets lack external signs of ovarian cyclicity, and cycle monitoring is done by regular determinations of progesterone. Cynomolgus and marmoset monkeys do not exhibit seasonal variations in ovarian activity, whereas such annual rhythm is pronounced in rhesus monkeys. Studies on pair- and group-housed cynomolgus monkeys revealed transient alterations in the duration and endocrinology of the ovarian cycle followed by return to normal cyclicity after approximately six months. This effect is avoided if the animals had contact with each other prior to mingling. These experiments also demonstrated that synchronization of ovarian cycles did not occur.
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Walker ML, Herndon JG. Menopause in nonhuman primates? Biol Reprod 2008; 79:398-406. [PMID: 18495681 PMCID: PMC2553520 DOI: 10.1095/biolreprod.108.068536] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2008] [Revised: 04/06/2008] [Accepted: 05/02/2008] [Indexed: 11/01/2022] Open
Abstract
A gradual alteration in the mechanisms underlying reproduction and fertility characterizes the aging process in human females. These changes culminate in menopause, conventionally defined as a cessation of menstrual cycles that marks the end of reproductive capacity. In fact, a central and defining event in menopause is the discontinuation of ovulation, which is correlated with a number of structural and functional changes in the reproductive axis. Despite several decades of research, a degree of uncertainty remains as to whether nonhuman primates undergo menopause, and whether they are suitable models of human reproductive senescence. We review some of the controversies that have clouded our understanding of reproductive aging in nonhuman primates, including issues of definition, timing, comparability of data from wild versus captive populations, and cross-species comparisons. The existing data support the view that menopause occurs in a number of primate species and is not unique to humans.
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Affiliation(s)
- Margaret L. Walker
- Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30322
| | - James G. Herndon
- Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30322
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Wilson AC, Clemente L, Liu T, Bowen RL, Meethal SV, Atwood CS. Reproductive hormones regulate the selective permeability of the blood-brain barrier. Biochim Biophys Acta Mol Basis Dis 2008; 1782:401-7. [DOI: 10.1016/j.bbadis.2008.02.011] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2007] [Revised: 02/21/2008] [Accepted: 02/25/2008] [Indexed: 10/22/2022]
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46
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Albertson AJ, Navratil A, Mignot M, Dufourny L, Cherrington B, Skinner DC. Immunoreactive GnRH type I receptors in the mouse and sheep brain. J Chem Neuroanat 2008; 35:326-33. [PMID: 18439800 DOI: 10.1016/j.jchemneu.2008.03.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2007] [Revised: 03/11/2008] [Accepted: 03/13/2008] [Indexed: 11/19/2022]
Abstract
Gonadotropin Releasing Hormone-I (GnRH) has been implicated in an array of functions outside the neuroendocrine reproductive axis. Previous investigations have reported extensive GnRH binding in numerous sites and this has been supported by in situ hybridization studies reporting GnRH receptor mRNA distribution. The present study on mice and sheep supports and extends these earlier investigations by revealing the distribution of cells immunoreactive for the GnRH receptor. In addition to sites previously shown to express GnRH receptors such as the hippocampus, amygdala and the arcuate nucleus, the improved resolution afforded by immunocytochemistry detected cells in the mitral cell lay of the olfactory bulb as well as the central grey of the mesencephalon. In addition, GnRH receptor immunoreactive neurons in the hippocampus and mesencephalon of the sheep were shown to colocalize with estrogen receptor beta. Although GnRH may act at some of these sites to regulate reproductive processes, evidence is accumulating to support an extra-reproductive role for this hypothalamic decapeptide.
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Affiliation(s)
- Asher J Albertson
- Department of Zoology and Physiology & Neurobiology Program, University of Wyoming, Dept 3166, 1000 E University Avenue, Laramie, WY 82071, USA
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Sherwin BB, Henry JF. Brain aging modulates the neuroprotective effects of estrogen on selective aspects of cognition in women: a critical review. Front Neuroendocrinol 2008; 29:88-113. [PMID: 17980408 DOI: 10.1016/j.yfrne.2007.08.002] [Citation(s) in RCA: 223] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2007] [Revised: 07/17/2007] [Accepted: 08/14/2007] [Indexed: 11/28/2022]
Abstract
Although there is now a substantial literature on the putative neuroprotective effects of estrogen on cognitive functioning in postmenopausal women, it is replete with inconsistencies. The critical period hypothesis, posited several years ago, attempts to account for the discrepancies in this literature by positing that estrogen treatment (ET) will protect aspects of cognition in older women only when treatment is initiated soon after the menopause. Indeed, evidence from basic neuroscience and from the animal and human literature reviewed herein provides compelling support for the critical period hypothesis. Although it is not known with certainty why estrogen does not protect cognition and may even cause harm when administered to women over the age of 65years, it is likely that the events that characterize brain aging, such as a reduction in brain volume and in neuronal size, alterations in neurotransmitter systems, and a decrease in dendritic spine numbers, form an unfavorable background that precludes a neuroprotective effects of exogenous estrogen on the brain. Other factors that have likely contributed to the discrepancies in the estrogen-cognition literature include differences in the estrogen compounds used, their route of administration, cyclic versus continuous regimens, and the concomitant use of progestins. This critical analysis attempts to define conditions under which ET may protect aspects of cognition in aging women while also considering the cost/benefit ratio for the treatment of women aged 50-59years. Suggestions for specific future research questions are also addressed.
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Affiliation(s)
- Barbara B Sherwin
- McGill University, Department of Psychology, 1205 Dr. Penfield Avenue, Montreal, Que., Canada.
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Morrison JH, Brinton RD, Schmidt PJ, Gore AC. Estrogen, menopause, and the aging brain: how basic neuroscience can inform hormone therapy in women. J Neurosci 2006; 26:10332-48. [PMID: 17035515 PMCID: PMC6674699 DOI: 10.1523/jneurosci.3369-06.2006] [Citation(s) in RCA: 237] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2006] [Revised: 08/31/2006] [Accepted: 09/04/2006] [Indexed: 12/30/2022] Open
Affiliation(s)
- John H Morrison
- Fishberg Department of Neuroscience, Kastor Neurobiology of Aging Laboratories, New York, New York 10029, USA.
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Downs JL, Urbanski HF. Neuroendocrine changes in the aging reproductive axis of female rhesus macaques (Macaca mulatta). Biol Reprod 2006; 75:539-46. [PMID: 16837643 DOI: 10.1095/biolreprod.106.051839] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Femalerhesus macaques show monthly menstrual cycles and eventually enter menopause at approximately 25 yr of age. To help identify early biomarkers of menopause in this nonhuman primate, we monitored reproductive hormones longitudinally from aged female macaques during the transitions from premenopause to perimenopause and postmenopause and found that, indeed, elevated plasma FSH was a better predictive factor of menopause onset than age. In a second experiment, we compared reproductive hormone profiles of young adult macaques (8-10 yr old) with those of regularly cycling old macaques (approximately 24 yr old). Indwelling vascular catheters were used for remote blood collection for at least 100 consecutive days, thereby covering three complete menstrual cycles in each macaque. Plasma levels of estradiol, progesterone, LH, FSH, follicular phase inhibin B, and anti-müllerian hormone (AMH) were determined during each menstrual cycle and were averaged for each animal; group mean differences were analyzed using one-way ANOVA. Old premenopausal macaques showed regular menstrual cycles that were qualitatively indistinguishable from those of young macaques; peak plasma levels of estradiol, progesterone, and LH were not significantly different. In marked contrast, peak plasma FSH concentrations were significantly higher, while inhibin B and AMH levels were generally lower, in the old premenopausal macaques compared with those in the young macaques. These data provide further evidence that rhesus macaques serve as an excellent model to study underlying mechanisms of human menopause. Furthermore, the data suggest that an age-related change in FSH, inhibin B, and AMH secretion may be the first endocrine manifestation of the transition into perimenopause, potentially having value in predicting the onset of the perimenopausal transition.
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Affiliation(s)
- Jodi L Downs
- Division of Neuroscience, Oregon National Primate Research Center, Beaverton, Oregon 97006, USA
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Sohrabji F. Estrogen: a neuroprotective or proinflammatory hormone? Emerging evidence from reproductive aging models. Ann N Y Acad Sci 2006; 1052:75-90. [PMID: 16024752 DOI: 10.1196/annals.1347.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Estrogen or hormone (estrogen + progestin) replacement is typically prescribed to women for relief from vasomotor symptoms at menopause. Observational studies have shown that such replacement also decreases the risk for Alzheimer's disease. Experimental data from a variety of animal models also suggest that estrogen replacement given to ovariectomized animals is largely neuroprotective. However, the recent intervention trial (Women's Health Initiative Memory Study; WHIMS) concluded that estrogen replacement and hormone replacement prescribed to postmenopausal women increased the risk for global cognitive impairment and dementia, respectively. This paper will examine evidence that the disparity in the human and animal data can be reconciled by consideration of the "reproductive" age of the individual receiving estrogen or hormone replacement. Our recent studies comparing the effects of estrogen replacement on young adult animals with those of estrogen replacement to reproductive senescent animals suggest that the estrogen replacement is beneficial when given to "surgically menopausal" (ovariectomized) animals. However, estrogen replacement appears to be deleterious to acyclic reproductive senescent animals, where target organs such as the brain have been in a prolonged estrogen-deficient state. The paper will also review aging and reproductive age-related changes in the estrogen receptor (ER) systems, specifically ER-alpha, as a potential mechanism for estrogen's deleterious effects in the reproductive senescent animal.
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Affiliation(s)
- Farida Sohrabji
- Department of Human Anatomy and Medical Neurobiology, College of Medicine, Texas A&M University Health Science Center, College Station, TX 77843, USA.
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