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Xu Q, Jin L, Wang L, Tang Y, Wu H, Chen Q, Sun L. The role of gonadal hormones in regulating opioid antinociception. Ann Med 2024; 56:2329259. [PMID: 38738380 PMCID: PMC11095291 DOI: 10.1080/07853890.2024.2329259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 03/06/2024] [Indexed: 05/14/2024] Open
Abstract
Opioids are the most prescribed drugs for the alleviation of pain. Both clinical and preclinical studies have reported strong evidence for sex-related divergence regarding opioid analgesia. There is an increasing amount of evidence indicating that gonadal hormones regulate the analgesic efficacy of opioids. This review presents an overview of the importance of gonadal steroids in modulating opioid analgesic responsiveness and focuses on elaborating what is currently known regarding the underlyingmechanism. We sought to identify the link between gonadal hormones and the effect of oipiod antinociception.
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Affiliation(s)
- Qi Xu
- Department of Anesthesiology, Women’s Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang Province, China
| | - Lin Jin
- Department of Anesthesiology, Women’s Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang Province, China
| | - LuYang Wang
- Department of Anesthesiology, Women’s Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang Province, China
| | - YingYing Tang
- Department of Anesthesiology, Women’s Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang Province, China
| | - Hui Wu
- Department of Anesthesiology, Women’s Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang Province, China
| | - Qing Chen
- Department of Anesthesiology, Women’s Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang Province, China
| | - LiHong Sun
- Department of Anesthesiology, Women’s Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang Province, China
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2
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Baumgartner NE, McQuillen SM, Perry SF, Miller S, Maroteaux MJ, Gibbs RB, Daniel JM. History of Previous Midlife Estradiol Treatment Permanently Alters Interactions of Brain Insulin-like Growth Factor-1 Signaling and Hippocampal Estrogen Synthesis to Enhance Cognitive Aging in a Rat Model of Menopause. J Neurosci 2022; 42:7969-7983. [PMID: 36261268 PMCID: PMC9617614 DOI: 10.1523/jneurosci.0588-22.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 08/20/2022] [Accepted: 08/24/2022] [Indexed: 11/24/2022] Open
Abstract
Across species, including humans, elevated levels of brain estrogen receptor (ER) α are associated with enhanced cognitive aging, even in the absence of circulating estrogens. In rodents, short-term estrogen treatment, such as that commonly used in the menopausal transition, results in long-term increases in ERα levels in the hippocampus, leading to enhanced memory long after termination of estrogen treatment. However, mechanisms by which increased levels of brain ERα enhances cognitive aging remain unclear. Here we demonstrate in aging female rats that insulin-like growth factor-1 (IGF-1), which can activate ER via ligand-independent mechanisms, requires concomitant synthesis of brain-derived neuroestrogens to phosphorylate ERα via MAPK signaling, ultimately resulting in enhanced memory. In a rat model of menopause involving long-term ovarian hormone deprivation, hippocampal neuroestrogen activity decreases, altering IGF-1 activity and resulting in impaired memory. However, this process is reversed by short-term estradiol treatment. Forty days of estradiol exposure following ovariectomy results in maintenance of neuroestrogen levels that persist beyond the period of hormone treatment, allowing for continued interactions between IGF-1 and neuroestrogen signaling, elevated levels of hippocampal ERα, and ultimately enhanced memory. Collectively, results demonstrate that short-term estradiol use following loss of ovarian function has long-lasting effects on hippocampal function and memory by dynamically regulating cellular mechanisms that promote activity of ERα in the absence of circulating estrogens. Translational impacts of these findings suggest lasting cognitive benefits of short-term estrogen use near menopause and highlight the importance of hippocampal ERα, independent from the role of circulating estrogens, in regulating memory in aging females.SIGNIFICANCE STATEMENT Declines in ovarian hormones following menopause coincide with increased risk of cognitive decline. Because of potential health risks, current recommendations are that menopausal estrogen therapy be limited to a few years. Long-term consequences for the brain and memory of this short-term midlife estrogen therapy are unclear. Here, in a rodent model of menopause, we determined mechanisms by which short-term midlife estrogen exposure can enhance hippocampal function and memory with cognitive benefits and molecular changes enduring long after termination of estrogen exposure. Our model indicates long-lasting benefits of maintaining hippocampal estrogen receptor function in the absence of ongoing estrogen exposure and suggests potential strategies for combating age-related cognitive decline.
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Affiliation(s)
| | | | | | | | - Matthieu J Maroteaux
- Brain Institute
- Neuroscience Program
- Department of Psychology, Tulane University, New Orleans, Louisiana 70118
| | - Robert B Gibbs
- Department of Pharmaceutical Sciences, University of Pittsburgh School of Pharmacy, Pittsburgh, Pennsylvania 15261
| | - Jill M Daniel
- Brain Institute
- Neuroscience Program
- Department of Psychology, Tulane University, New Orleans, Louisiana 70118
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3
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Immunofluorescent Evidence for Nuclear Localization of Aromatase in Astrocytes in the Rat Central Nervous System. Int J Mol Sci 2022; 23:ijms23168946. [PMID: 36012212 PMCID: PMC9408820 DOI: 10.3390/ijms23168946] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 08/06/2022] [Accepted: 08/09/2022] [Indexed: 11/22/2022] Open
Abstract
Estrogens regulate a variety of neuroendocrine, reproductive and also non-reproductive brain functions. Estradiol biosynthesis in the central nervous system (CNS) is catalyzed by the enzyme aromatase, which is expressed in several brain regions by neurons, astrocytes and microglia. In this study, we performed a complex fluorescent immunocytochemical analysis which revealed that aromatase is colocalized with the nuclear stain in glial fibrillary acidic protein (GFAP) positive astrocytes in cell cultures. Confocal immunofluorescent Z-stack scanning analysis confirmed the colocalization of aromatase with the nuclear DAPI signal. Nuclear aromatase was also detectable in the S100β positive astrocyte subpopulation. When the nuclear aromatase signal was present, estrogen receptor alpha was also abundant in the nucleus. Immunostaining of frozen brain tissue sections showed that the nuclear colocalization of the enzyme in GFAP-positive astrocytes is also detectable in the adult rat brain. CD11b/c labelled microglial cells express aromatase, but the immunopositive signal was distributed only in the cytoplasm both in the ramified and amoeboid microglial forms. Immunostaining of rat ovarian tissue sections and human granulosa cells revealed that aromatase was present only in the cytoplasm. This novel observation suggests a new unique mechanism in astrocytes that may regulate certain CNS functions via estradiol production.
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Arbiters of endogenous opioid analgesia: role of CNS estrogenic and glutamatergic systems. Transl Res 2021; 234:31-42. [PMID: 33567346 PMCID: PMC8217383 DOI: 10.1016/j.trsl.2021.02.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 02/01/2021] [Accepted: 02/02/2021] [Indexed: 11/24/2022]
Abstract
Nociception and opioid antinociception in females are pliable processes, varying qualitatively and quantitatively over the reproductive cycle. Spinal estrogenic signaling via membrane estrogen receptors (mERs), in combination with multiple other signaling molecules [spinal dynorphin, kappa-opioid receptors (KOR), glutamate and metabotropic glutamate receptor 1 (mGluR1)], appears to function as a master coordinator, parsing functionality between pronociception and antinociception. This provides a window into pharmacologically accessing intrinsic opioid analgesic/anti-allodynic systems. In diestrus, membrane estrogen receptor alpha (mERα) signals via mGluR1 to suppress spinal endomorphin 2 (EM2) analgesia. Strikingly, in the absence of exogenous opioids, interfering with this suppression in a chronic pain model elicits opioid anti-allodynia, revealing contributions of endogenous opioid(s). In proestrus, robust spinal EM2 analgesia is manifest but this requires spinal dynorphin/KOR and glutamate-activated mGluR1. Furthermore, spinal mGluR1 blockade in a proestrus chronic pain animal (eliminating spinal EM2 analgesia) exacerbates mechanical allodynia, revealing tempering by endogenous opioid(s). A complex containing mu-opioid receptor, KOR, aromatase, mGluRs, and mERα are foundational to eliciting endogenous opioid anti-allodynia. Aromatase-mERα oligomers are also plentiful, in a central nervous system region-specific fashion. These can be independently regulated and allow estrogens to act intracellularly within the same signaling complex in which they are synthesized, explaining asynchronous relationships between circulating estrogens and central nervous system estrogen functionalities. Observations with EM2 highlight the translational relevance of extensively characterizing exogenous responsiveness to endogenous opioids and the neuronal circuits that mediate them along with the multiplicity of estrogenic systems that concomitantly function in phase and out-of-phase with the reproductive cycle.
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Abstract
This paper is the fortieth consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2017 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, CUNY, 65-30 Kissena Blvd., Flushing, NY, 11367, United States.
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6
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Xu Q, Sun L, Zhang W, Chen S, Wu H, Jiao C, Fu F, Feng Y, Yao H, Chen Q, Chen X. Effect of chronic pretreatment with 17β-estradiol and/or progesterone on the nociceptive response to uterine cervical distension in a rat model. Eur J Pharmacol 2019; 865:172791. [PMID: 31712057 DOI: 10.1016/j.ejphar.2019.172791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 11/05/2019] [Accepted: 11/07/2019] [Indexed: 10/25/2022]
Abstract
It is widely known that visceral pain is more prevalent in women than in men, and this phenomenon is interpreted as a consequence of the gonadal hormone modulation of pain perception and transduction. Uterine cervical distension might cause obstetric and gynecologic pain with clinical relevance to visceral pain. In this study, we focused on the roles of 17β-estradiol and progesterone in visceral nociception with the use of a rat model of uterine cervical distension. Female ovariectomized rats were injected with 17β-estradiol (E2) or progesterone (P4) for 21 days, after which visceral pain-induced spinal c-fos expression and visceromotor reflex changes were compared between ovariectomized and hormone-substituted groups. We found that uterine cervical distension induced a drastic increase in spinal c-fos expression and visceromotor reflex activity, and ovariectomy inhibited the increase in c-fos expression induced by visceral pain; this inhibition was reversed by estrogen but not progesterone replacement. This study demonstrates that estrogen is involved in uterine cervical nociception, while progesterone plays less of a significant role.
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Affiliation(s)
- Qi Xu
- Department of Anesthesia, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Lihong Sun
- Department of Anesthesia, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Wenxin Zhang
- Department of Anesthesia, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Sheng Chen
- Department of Anesthesia, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Hui Wu
- Department of Anesthesia, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Cuicui Jiao
- Department of Anesthesia, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Feng Fu
- Department of Anesthesia, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Ying Feng
- Department of Anesthesia, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Huaqi Yao
- Department of Anesthesia, Maternity and Child Care Hospital, Huzhou, China
| | - Qing Chen
- Department of Anesthesia, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Xinzhong Chen
- Department of Anesthesia, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
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Balthazart J. New concepts in the study of the sexual differentiation and activation of reproductive behavior, a personal view. Front Neuroendocrinol 2019; 55:100785. [PMID: 31430485 PMCID: PMC6858558 DOI: 10.1016/j.yfrne.2019.100785] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Revised: 08/13/2019] [Accepted: 08/16/2019] [Indexed: 01/09/2023]
Abstract
Since the beginning of this century, research methods in neuroendocrinology enjoyed extensive refinements and innovation. These advances allowed collection of huge amounts of new data and the development of new ideas but have not led to this point, with a few exceptions, to the development of new conceptual advances. Conceptual advances that took place largely resulted from the ingenious insights of several investigators. I summarize here some of these new ideas as they relate to the sexual differentiation and activation by sex steroids of reproductive behaviors and I discuss how our research contributed to the general picture. This selective review clearly demonstrates the importance of conceptual changes that have taken place in this field since beginning of the 21st century. The recent technological advances suggest that our understanding of hormones, brain and behavior relationships will continue to improve in a very fundamental manner over the coming years.
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Gintzler AR, Storman EM, Liu NJ. Estrogens as arbiters of sex-specific and reproductive cycle-dependent opioid analgesic mechanisms. VITAMINS AND HORMONES 2019; 111:227-246. [PMID: 31421702 PMCID: PMC7136895 DOI: 10.1016/bs.vh.2019.06.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The organization of estrogenic signaling in the CNS is exceedingly complex. It is comprised of peripherally and centrally synthesized estrogens, and a plethora of types of estrogen receptor that can localize to both the nucleus and the plasma membrane. Moreover, CNS estrogen receptors can exist independent of aromatase (aka estrogen synthase) as well as oligomerize with it, along with a host of other membrane signaling proteins. This ability of CNS estrogen receptors to either to physically pair or exist separately enables locally produced estrogens to act on multiple spatial levels, with a high degree of gradated regulation and plasticity, signaling either in-phase or out-of phase with circulating estrogens. This complexity explains the numerous contradictory findings regarding sex-dependent pain processing and sexually dimorphic opioid antinociception. This review highlights the increasing awareness that estrogens are major endogenous arbiters of both opioid analgesic actions and the mechanisms used to achieve them. This behooves us to understand, and possibly intercede at, the points of intersection of estrogenic signaling and opioid functionality. Factors that integrate estrogenic actions at subcellular, synaptic, and CNS regional levels are likely to be prime drug targets for novel pharmacotherapies designed to modulate CNS estrogen-dependent opioid functionalities and possibly circumvent the current opioid epidemic.
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MESH Headings
- Analgesia
- Analgesics, Opioid/pharmacology
- Animals
- Aromatase
- Brain/physiology
- Dynorphins/physiology
- Estrogens/physiology
- Female
- Humans
- Male
- Neurosecretory Systems/physiology
- Nociception/drug effects
- Nociception/physiology
- Receptors, Estrogen/physiology
- Receptors, Opioid, kappa/drug effects
- Receptors, Opioid, kappa/physiology
- Receptors, Opioid, mu/drug effects
- Receptors, Opioid, mu/physiology
- Reproduction/physiology
- Sex Characteristics
- Signal Transduction/physiology
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Affiliation(s)
- Alan R Gintzler
- Department of Obstetrics and Gynecology, State University of New York, Downstate Medical Center, Brooklyn, NY, United States.
| | - Emiliya M Storman
- Department of Obstetrics and Gynecology, State University of New York, Downstate Medical Center, Brooklyn, NY, United States
| | - Nai-Jiang Liu
- Department of Obstetrics and Gynecology, State University of New York, Downstate Medical Center, Brooklyn, NY, United States
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Gintzler AR, Liu NJ, Storman EM, Wessendorf MW. Exploiting endogenous opioids: Lessons learned from endomorphin 2 in the female rat. Peptides 2019; 112:133-138. [PMID: 30557590 PMCID: PMC7173356 DOI: 10.1016/j.peptides.2018.12.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 11/30/2018] [Accepted: 12/03/2018] [Indexed: 02/06/2023]
Abstract
Effective management of chronic pain is demanded by ethical as well as medical considerations. Although opioid analgesics remain among the most effective pharmacotherapies for ameliorating many types of pain, their use is clouded by concerns regarding their addictive properties, underscored by the current epidemic of prescription opioid abuse and attendant deaths. Medicinal harnessing of endogenous opioid antinociception could provide a strategy for continuing to take advantage of the powerful antinociceptive properties of opioids while avoiding their abuse potential. Based on our studies of endogenous mechanism that suppress and facilitate spinal endomorphin 2 antinociception over the rat reproductive cycle, we identified multiple signaling molecules that could serve as targets for activating endogenous opioid analgesia for chronic pain management in women. Our findings emphasize the need for a precision medicine approach that includes stage of menstrual cycle as an important determinant of drug targets for (activating/harnessing) endogenous opioid antinociceptive systems/ capabilities. Utilization of drugs that harness endogenous opioid antinociception in accordance with varying physiological states represents a novel approach for effective pain management.
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Affiliation(s)
- Alan R Gintzler
- Department of Obstetrics and Gynecology, State University of New York, Downstate Medical Center, 450 Clarkson Ave, Brooklyn, NY, 11203, USA.
| | - Nai-Jiang Liu
- Department of Obstetrics and Gynecology, State University of New York, Downstate Medical Center, 450 Clarkson Ave, Brooklyn, NY, 11203, USA
| | - Emiliya M Storman
- Department of Obstetrics and Gynecology, State University of New York, Downstate Medical Center, 450 Clarkson Ave, Brooklyn, NY, 11203, USA
| | - Martin W Wessendorf
- Department of Neuroscience, School of Medicine, University of Minnesota, Minneapolis, MN 55455, USA
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Gintzler AR, Liu NJ. Harnessing endogenous opioids for pain relief: Fantasy vs reality. J Opioid Manag 2019; 16:67-72. [PMID: 32091619 PMCID: PMC8244826 DOI: 10.5055/jom.2020.0552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
OBJECTIVE To review evidence demonstrating efficacy and feasibility of harnessing the activity of endogenous opioid analgesic systems for pain management. METHODS The authors sought to summarize a wealth of data that establish proof of concept that the analgesic activity of endogenous opioids can be exploited to clinically benefit from the enormous pain-relieving abilities of these peptides without contributing to the current crisis of death by synthetic opioid overdose. RESULTS There is a plethora of studies demonstrating that not only can endogenous opioids mediate placebo-induced antinociception but they are also active in modulating clinical pain. Earlier studies convincingly demonstrate the effec-tiveness of psychological strategies to coopt endogenous opioid analgesic systems to produce pain relief. The challenge is to define pharmacological targets for activating endogenous opioid analgesia reliably in a clinical setting. Based on insights gleaned from mechanisms underlying the ebb and flow of analgesic responsiveness to the spinal application of endomorphin 2, multiple signaling proteins were identified that activate endogenous spinal opioid analgesia. Notably, this was achieved in the absence of any exogenous synthetic opioid. CONCLUSIONS Utilization of drugs that harness endogenous opioid antinociception in accordance with varying physiological states represents a novel approach for effective pain management while mitigating the present epidemic of death by synthetic opioid overdose.
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Affiliation(s)
- Alan R Gintzler
- Department of Obstetrics and Gynecology, State University of New York, Downstate Medical Center, Brooklyn, New York
| | - Nai-Jiang Liu
- Department of Obstetrics and Gynecology, State University of New York, Downstate Medical Center, Brooklyn, New York
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11
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Liu NJ, Storman EM, Gintzler AR. Pharmacological Modulation of Endogenous Opioid Activity to Attenuate Neuropathic Pain in Rats. THE JOURNAL OF PAIN 2018; 20:235-243. [PMID: 30366152 DOI: 10.1016/j.jpain.2018.10.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 09/12/2018] [Accepted: 10/17/2018] [Indexed: 12/23/2022]
Abstract
We showed previously that spinal metabotropic glutamate receptor 1 (mGluR1) signaling suppresses or facilitates (depending on the stage of estrous cycle) analgesic responsiveness to intrathecal endomorphin 2, a highly mu-opioid receptor-selective endogenous opioid. Spinal endomorphin 2 antinociception is suppressed during diestrus by mGluR1 when it is activated by membrane estrogen receptor alpha (mERα) and is facilitated during proestrus when mGluR1 is activated by glutamate. In the current study, we tested the hypothesis that in female rats subjected to spinal nerve ligation (SNL), the inhibition of spinal estrogen synthesis or blockade of spinal mERα/mGluR1 would be antiallodynic during diestrus, whereas during proestrus, mGluR1 blockade would worsen the mechanical allodynia. As postulated, following SNL, aromatase inhibition or mERα/mGluR1 blockade during diestrus markedly lessened the mechanical allodynia. This was observed only on the paw ipsilateral to SNL and was eliminated by naloxone, implicating endogenous opioid mediation. In contrast, during proestrus, mGluR1 blockade worsened the SNL-induced mechanical allodynia of the ipsilateral paw. Findings suggest menstrual cycle stage-specific drug targets for and the putative clinical utility of harnessing endogenous opioids for chronic pain management in women, as well as the value of, if not the necessity for, considering menstrual cycle stage in clinical trials thereof. PERSPECTIVE: Intrathecal treatments that enhance spinal endomorphin 2 analgesic responsiveness under basal conditions lessen mechanical allodynia in a chronic pain model. Findings provide a foundation for developing drugs that harness endogenous opioid antinociception for chronic pain relief, lessening the need for exogenous opioids and thus prescription opioid abuse.
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Affiliation(s)
- Nai-Jiang Liu
- Department of Obstetrics and Gynecology, State University of New York, Downstate Medical Center, Brooklyn, New York
| | - Emiliya M Storman
- Department of Obstetrics and Gynecology, State University of New York, Downstate Medical Center, Brooklyn, New York
| | - Alan R Gintzler
- Department of Obstetrics and Gynecology, State University of New York, Downstate Medical Center, Brooklyn, New York..
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Brocca ME, Garcia-Segura LM. Non-reproductive Functions of Aromatase in the Central Nervous System Under Physiological and Pathological Conditions. Cell Mol Neurobiol 2018; 39:473-481. [PMID: 30084008 DOI: 10.1007/s10571-018-0607-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 07/25/2018] [Indexed: 02/07/2023]
Abstract
The modulation of brain function and behavior by steroid hormones was classically associated with their secretion by peripheral endocrine glands. The discovery that the brain expresses the enzyme aromatase, which produces estradiol from testosterone, expanded this traditional concept. One of the best-studied roles of brain estradiol synthesis is the control of reproductive behavior. In addition, there is increasing evidence that estradiol from neural origin is also involved in a variety of non-reproductive functions. These include the regulation of neurogenesis, neuronal development, synaptic transmission, and plasticity in brain regions not directly related with the control of reproduction. Central aromatase is also involved in the modulation of cognition, mood, and non-reproductive behaviors. Furthermore, under pathological conditions aromatase is upregulated in the central nervous system. This upregulation represents a neuroprotective and likely also a reparative response by increasing local estradiol levels in order to maintain the homeostasis of the neural tissue. In this paper, we review the non-reproductive functions of neural aromatase and neural-derived estradiol under physiological and pathological conditions. We also consider the existence of sex differences in the role of the enzyme in both contexts.
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Affiliation(s)
- Maria Elvira Brocca
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain.
| | - Luis Miguel Garcia-Segura
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
- Centro de Investigación Biomédica en Red Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
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13
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Storman EM, Liu NJ, Wessendorf MW, Gintzler AR. Physical Linkage of Estrogen Receptor α and Aromatase in Rat: Oligocrine and Endocrine Actions of CNS-Produced Estrogens. Endocrinology 2018; 159:2683-2697. [PMID: 29771302 PMCID: PMC6692873 DOI: 10.1210/en.2018-00319] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 05/08/2018] [Indexed: 12/11/2022]
Abstract
Rapid-signaling membrane estrogen receptors (mERs) and aromatase (Aro) are present throughout the central nervous system (CNS), enabling acute regulation of CNS estrogenic signaling. We previously reported that spinal membrane Aro (mAro) and mERα oligomerize (1). As their organizational relationship would likely influence functions of locally produced estrogens, we quantified the mAro and mERα that are physically associated and nonassociated in two functionally different regions of rat CNS: the spinal cord, which has predominantly neural functionalities, and the hypothalamus, which has both neural and endocrine capabilities. Quantitative immunoprecipitation (IP), coimmunoprecipitation, and Western blot analysis were used to quantify the associated and nonassociated subpopulations of mAro and mERα. Regardless of estrous-cycle stage, virtually all mAro was oligomerized with mERα in the spinal cord, whereas only ∼15% was oligomerized in the hypothalamus. The predominance of nonassociated mAro in the hypothalamus, in combination with findings that many hypothalamic Aro-immunoreactive neurons could be retrogradely labeled with peripherally injected Fluoro-Gold, suggests that a portion of hypothalamic estrogens is secreted, potentially regulating pituitary function. Moreover, circulating estrogens increased hypothalamic Aro activity (quantified by the tritiated water-release assay) in the absence of increased Aro protein, revealing nongenomic regulation of Aro activity in the mammalian CNS. The demonstrated presence of associated and nonassociated mAro and mERα subpopulations in the CNS suggests that their selective targeting could restore impaired estrogen-dependent CNS functionalities while minimizing unwanted effects. The full physiological ramifications of brain-secreted estrogens remain to be explored.
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Affiliation(s)
- Emiliya M Storman
- Department of Obstetrics and Gynecology, State University of New York, Downstate Medical Center, Brooklyn, New York
| | - Nai-Jiang Liu
- Department of Obstetrics and Gynecology, State University of New York, Downstate Medical Center, Brooklyn, New York
| | - Martin W Wessendorf
- Department of Neuroscience, School of Medicine, University of Minnesota, Minneapolis, Minnesota
| | - Alan R Gintzler
- Department of Obstetrics and Gynecology, State University of New York, Downstate Medical Center, Brooklyn, New York
- Correspondence: Alan R. Gintzler, PhD, SUNY Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, New York 11203. E-mail:
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Plasticity of Signaling by Spinal Estrogen Receptor α, κ-Opioid Receptor, and Metabotropic Glutamate Receptors over the Rat Reproductive Cycle Regulates Spinal Endomorphin 2 Antinociception: Relevance of Endogenous-Biased Agonism. J Neurosci 2017; 37:11181-11191. [PMID: 29025923 DOI: 10.1523/jneurosci.1927-17.2017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 09/06/2017] [Accepted: 10/02/2017] [Indexed: 01/22/2023] Open
Abstract
We previously showed that intrathecal application of endomorphin 2 [EM2; the highly specific endogenous μ-opioid receptor (MOR) ligand] induces antinociception that varies with stage of the rat estrous cycle: minimal during diestrus and prominent during proestrus. Earlier studies, however, did not identify proestrus-activated signaling strategies that enable spinal EM2 antinociception. We now report that in female rats, increased spinal dynorphin release and κ-opioid receptor (KOR) signaling, as well as the emergence of glutamate-activated metabotropic glutamate receptor 1 (mGluR1) signaling, are critical to the transition from an EM2 nonresponsive state (during diestrus) to an analgesically responsive state (during proestrus). Differential signaling by mGluR1, depending on its activation by membrane estrogen receptor α (mERα; during diestrus) versus glutamate (during proestrus), concomitant with the ebb and flow of spinal dynorphin/KOR signaling, functions as a switch, preventing or promoting, respectively, spinal EM2 antinociception. Importantly, EM2 and glutamate-containing varicosities appose spinal neurons that express MOR along with mGluRs and mERα, suggesting that signaling mechanisms regulating analgesic effectiveness of intrathecally applied EM2 also pertain to endogenous EM2. Regulation of spinal EM2 antinociception by both the nature of the endogenous mGluR1 activator (i.e., endogenous biased agonism at mGluR1) and changes in spinal dynorphin/KOR signaling represent a novel mechanism for modulating analgesic responsiveness to endogenous EM2 (and perhaps other opioids). This points the way for developing noncanonical pharmacological approaches to pain management by harnessing endogenous opioids for pain relief.SIGNIFICANCE STATEMENT The current prescription opioid abuse epidemic underscores the urgency to develop alternative pharmacotherapies for managing pain. We find that the magnitude of spinal endomorphin 2 (EM2) antinociception not only varies with stage of reproductive cycle, but is also differentially regulated during diestrus and proestrus. This finding highlights the need for sex-specific and cycle-specific approaches to pain management. Additionally, our finding that spinal EM2 antinociception in female rats is regulated by both the ebb and flow of spinal dynorphin/κ-opioid receptor signaling over the estrous cycle, as well as the nature of the endogenous mGluR1 activator, could encourage noncanonical pharmacological approaches to pain management, such as harnessing endogenous opioids for pain relief.
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