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Inhibition of miR-181a protects female mice from transient focal cerebral ischemia by targeting astrocyte estrogen receptor-α. Mol Cell Neurosci 2017; 82:118-125. [PMID: 28522364 DOI: 10.1016/j.mcn.2017.05.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 05/03/2017] [Accepted: 05/08/2017] [Indexed: 02/03/2023] Open
Abstract
Whether the effect of miR-181a is sexually dimorphic in stroke is unknown. Prior work showed protection of male mice with miR-181a inhibition. Estrogen receptor-α (ERα) is an identified target of miR181 in endometrium. Therefore we investigated the separate and joint effects of miR-181a inhibition and 17β-estradiol (E2) replacement after ovariectomy. Adult female mice were ovariectomized and implanted with an E2- or vehicle-containing capsule for 14d prior to 1h middle cerebral artery occlusion (MCAO). Each group received either miR-181a antagomir or mismatch control by intracerebroventricular injection 24h before MCAO. After MCAO neurologic deficit and infarct volume were assessed. Primary male and female astrocyte cultures were subjected to glucose deprivation with miR-181a inhibitor or transfection control, and E2 or vehicle control, with/without ESRα knockdown with small interfering RNA. Cell death was assessed by propidium iodide staining, and lactate dehydrogenase assay. A miR-181a/ERα target site blocker (TSB), with/without miR-181a mimic, was used to confirm targeting of ERα by miR-181a in astrocytes. Individually, miR-181a inhibition or E2 decreased infarct volume and improved neurologic score in female mice, and protected male and female astrocyte cultures. Combined miR-181a inhibition plus E2 afforded greater protection of female mice and female astrocyte cultures, but not in male astrocyte cultures. MiR-181a inhibition only increased ERα levels in vivo and in female cultures, while ERα knockdown with siRNA increased cell death in both sexes. Treatment with ERα TSB was strongly protective in both sexes. In conclusion, the results of the present study suggest miR-181a inhibition enhances E2-mediated stroke protection in females in part by augmenting ERα production, a mechanism detected in female mice and female astrocytes. Sex differences were observed with combined miR-181a inhibition/E2 treatment, and miR-181a targeting of ERα.
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Uchoa MF, Moser VA, Pike CJ. Interactions between inflammation, sex steroids, and Alzheimer's disease risk factors. Front Neuroendocrinol 2016; 43:60-82. [PMID: 27651175 PMCID: PMC5123957 DOI: 10.1016/j.yfrne.2016.09.001] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 09/10/2016] [Accepted: 09/14/2016] [Indexed: 12/19/2022]
Abstract
Alzheimer's disease (AD) is an age-related neurodegenerative disorder for which there are no effective strategies to prevent or slow its progression. Because AD is multifactorial, recent research has focused on understanding interactions among the numerous risk factors and mechanisms underlying the disease. One mechanism through which several risk factors may be acting is inflammation. AD is characterized by chronic inflammation that is observed before clinical onset of dementia. Several genetic and environmental risk factors for AD increase inflammation, including apolipoprotein E4, obesity, and air pollution. Additionally, sex steroid hormones appear to contribute to AD risk, with age-related losses of estrogens in women and androgens in men associated with increased risk. Importantly, sex steroid hormones have anti-inflammatory actions and can interact with several other AD risk factors. This review examines the individual and interactive roles of inflammation and sex steroid hormones in AD, as well as their relationships with the AD risk factors apolipoprotein E4, obesity, and air pollution.
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Affiliation(s)
- Mariana F Uchoa
- Neuroscience Graduate Program, University of Southern California, Los Angeles, CA 90089, USA
| | - V Alexandra Moser
- Neuroscience Graduate Program, University of Southern California, Los Angeles, CA 90089, USA
| | - Christian J Pike
- Neuroscience Graduate Program, University of Southern California, Los Angeles, CA 90089, USA; Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA 90089, USA.
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Liu L, Liu L, Shi J, Tan M, Xiong J, Li X, Hu Q, Yi Z, Mao D. MicroRNA-34b mediates hippocampal astrocyte apoptosis in a rat model of recurrent seizures. BMC Neurosci 2016; 17:56. [PMID: 27514646 PMCID: PMC4981991 DOI: 10.1186/s12868-016-0291-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 07/21/2016] [Indexed: 01/03/2023] Open
Abstract
Background Recurrent convulsions can cause irreversible astrocyte death, impede neuron regeneration, and further aggravate brain damage. MicroRNAs have been revealed as players in the progression of numerous diseases including cancer and Alzheimer’s disease. Particularly, microRNA has been found linked to seizure-induced neuronal death. In this study, a rat model of recurrent convulsions induced by flurothyl treatments was utilised to assess the alterations of microRNA expressions in hippocampus tissues. We also applied an in vitro model in which primary astrocytes were exposed to kainic acid to verify the targets of miR-34b-5p identified in the animal model. Results We discovered that miR-34b-5p, a member of the miR-34 family, increased significantly in flurothyl-treated rat hippocampus tissue. More surprisingly, this upregulation occurred concurrently with accumulating astrocyte apoptosis, indicating the involvement of miR-34b-5p in seizures caused astrocyte apoptosis. Results from the in vitro experiments further demonstrated that miR-34b-5p directly targeted Bcl-2 mRNA, translationally repressed Bcl-2 protein, and thus modulated cell apoptosis by influencing Bcl-2, Bax, and Caspase-3. Conclusion Our findings prove microRNAs play a role in mediating recurrent convulsions-induced astrocyte death and further indicate that miR-34b-5p could acts as a regulator for astrocyte apoptosis induced by recurrent seizures. Electronic supplementary material The online version of this article (doi:10.1186/s12868-016-0291-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Liqun Liu
- Department of Pediatrics, The Second Xiangya Hospital of Central South University, 86 Renmin Middle Rd, Changsha, 410011, Hunan, People's Republic of China
| | - Lingjuan Liu
- Department of Pediatrics, The Second Xiangya Hospital of Central South University, 86 Renmin Middle Rd, Changsha, 410011, Hunan, People's Republic of China
| | - Jiayun Shi
- Department of Pediatrics, The Second Xiangya Hospital of Central South University, 86 Renmin Middle Rd, Changsha, 410011, Hunan, People's Republic of China
| | - Menglin Tan
- Department of Pediatrics, The Second Xiangya Hospital of Central South University, 86 Renmin Middle Rd, Changsha, 410011, Hunan, People's Republic of China
| | - Jie Xiong
- Department of Pediatrics, The Second Xiangya Hospital of Central South University, 86 Renmin Middle Rd, Changsha, 410011, Hunan, People's Republic of China
| | - Xingfang Li
- Department of Pediatrics, The Second Xiangya Hospital of Central South University, 86 Renmin Middle Rd, Changsha, 410011, Hunan, People's Republic of China
| | - Qingpeng Hu
- Department of Pediatrics, The Second Xiangya Hospital of Central South University, 86 Renmin Middle Rd, Changsha, 410011, Hunan, People's Republic of China
| | - Zhuwen Yi
- Department of Pediatrics, The Second Xiangya Hospital of Central South University, 86 Renmin Middle Rd, Changsha, 410011, Hunan, People's Republic of China
| | - Ding'an Mao
- Department of Pediatrics, The Second Xiangya Hospital of Central South University, 86 Renmin Middle Rd, Changsha, 410011, Hunan, People's Republic of China.
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4
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Wang C, Jie C, Dai X. Possible roles of astrocytes in estrogen neuroprotection during cerebral ischemia. Rev Neurosci 2014; 25:255-68. [PMID: 24566361 DOI: 10.1515/revneuro-2013-0055] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Accepted: 01/29/2014] [Indexed: 01/08/2023]
Abstract
17β-Estradiol (E2), one of female sex hormones, has well-documented neuroprotective effects in a variety of clinical and experimental disorders of the central cerebral ischemia, including stroke and neurodegenerative diseases. The cellular mechanisms that underlie these protective effects of E2 are uncertain because a number of different cell types express estrogen receptors in the central nervous system. Astrocytes are the most abundant cells in the central nervous system and provide structural and nutritive support of neurons. They interact with neurons by cross-talk, both physiologically and pathologically. Proper astrocyte function is particularly important for neuronal survival under ischemic conditions. Dysfunction of astrocytes resulting from ischemia significantly influences the responses of other brain cells to injury. Recent studies demonstrate that estrogen receptors are expressed in astrocytes, indicating that E2 may exert multiple regulatory actions on astrocytes. Cerebral ischemia induced changes in the expression of estrogen receptors in astrocytes. In the present review, we summarize the data in support of possible roles for astrocytes in the mediation of neuroprotection by E2 against cerebral ischemia.
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Liu MH, Lin YS, Sheu SY, Sun JS. Anti-inflammatory effects of daidzein on primary astroglial cell culture. Nutr Neurosci 2013; 12:123-34. [DOI: 10.1179/147683009x423274] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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Duncan KA, Walters BJ, Saldanha CJ. Traumatized and inflamed--but resilient: glial aromatization and the avian brain. Horm Behav 2013; 63:208-15. [PMID: 22414444 PMCID: PMC9366899 DOI: 10.1016/j.yhbeh.2012.02.026] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Revised: 02/26/2012] [Accepted: 02/27/2012] [Indexed: 01/08/2023]
Abstract
Steroids like estrogens have potent effects on the vertebrate brain, and are provided to neural targets from peripheral and central sources. Estradiol synthesized within the vertebrate CNS modulates neural structure and function, including the pathways involved in neuroprotection, and perhaps, neural repair. Specifically, aromatase; the enzyme responsible for the conversion of testosterone to estradiol, is upregulated in the avian and mammalian brain following disruption of the neuropil by multiple forms of perturbation including mechanical injury, ischemia and excitotoxicity. This injury induced aromatase expression is somewhat unique in that it occurs in astroglia rather than neurons, and is stimulated in response to factors associated with brain damage. In this review, we focus on the induction, expression and consequences of glial aromatization in the songbird brain. We begin with a review of the anatomical consequences of glial estrogen provision followed by a discussion of the cellular mechanisms whereby glial aromatization may affect injury-induced neuroplasticity. We then present the current status of our understanding regarding the inductive role of inflammatory processes in the transcription and translation of astrocytic aromatase. We consider the functional aspects of glial aromatization before concluding with unanswered questions and suggestions for future studies. Birds have long informed us about fundamental questions in endocrinology, immunology, and neuroplasticity; and their unique anatomical and physiological characteristics continue to provide an excellent system in which to learn about brain trauma, inflammation, and neuroprotection.
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Affiliation(s)
- Kelli A. Duncan
- Department of Biology, Vassar College, Poughkeepsie, NY 12604, USA
| | - Bradley J. Walters
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Colin J. Saldanha
- Department of Biology, American University, Washington DC, 20016, USA
- Department of Psychology, American University, Washington DC, 20016, USA
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Azcoitia I, Santos-Galindo M, Arevalo MA, Garcia-Segura LM. Role of astroglia in the neuroplastic and neuroprotective actions of estradiol. Eur J Neurosci 2010; 32:1995-2002. [DOI: 10.1111/j.1460-9568.2010.07516.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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8
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Actions of estrogens on glial cells: Implications for neuroprotection. Biochim Biophys Acta Gen Subj 2010; 1800:1106-12. [DOI: 10.1016/j.bbagen.2009.10.002] [Citation(s) in RCA: 148] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2009] [Revised: 09/29/2009] [Accepted: 10/01/2009] [Indexed: 01/21/2023]
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9
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Scott AL, Ramer MS. Differential regulation of dendritic plasticity by neurotrophins following deafferentation of the adult spinal cord is independent of p75NTR. Brain Res 2010; 1323:48-58. [DOI: 10.1016/j.brainres.2010.02.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2009] [Revised: 01/26/2010] [Accepted: 02/02/2010] [Indexed: 12/16/2022]
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Barker JM, Galea LAM. Males show stronger contextual fear conditioning than females after context pre-exposure. Physiol Behav 2010; 99:82-90. [PMID: 19879284 DOI: 10.1016/j.physbeh.2009.10.014] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2009] [Revised: 10/17/2009] [Accepted: 10/22/2009] [Indexed: 10/20/2022]
Abstract
Estradiol affects the structure and function of the hippocampus. We have found that repeated estradiol affects neurogenesis and cell death in the hippocampus of adult female, but not male rats. In the present study we sought to determine whether using the same regimen of estradiol would influence hippocampus-dependent behaviour. Adult male and female rats were given estradiol or sesame oil for 15 days, and then tested using a contextual pre-exposure paradigm in which performance depends on the hippocampus. The time spent freezing displayed by rats was scored on subsequent days in (1) the training context, (2) a novel context in which rats had never been shocked, and (3) the training context a second time. Irrespective of treatment, males showed stronger memory for the context by exhibiting greater freezing in both the training context exposures and the novel context. Previous estradiol treatment, in either sex, did not affect the ability to learn and retain information about the training context. However, female rats treated with estradiol and exposed to a novel context after fear conditioning exhibited less freezing behaviour than controls. Taken together, our results demonstrate that gonadectomized male rats outperform females, regardless of previous treatment with estradiol, on a hippocampus-contextual fear conditioning test, and that previous estradiol treatment has a subtle effect on performance in female but not male rats.
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Affiliation(s)
- Jennifer M Barker
- Graduate Program in Neuroscience, Brain Research Centre, Department of Psychology, University of British Columbia, Vancouver, British Columbia, Canada
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11
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Küst BM, Brouwer N, Mantingh IJ, Boddeke HWGM, Copray JCVM. Reduced p75NTRexpression delays disease onset only in female mice of a transgenic model of familial amyotrophic lateral sclerosis. ACTA ACUST UNITED AC 2009. [DOI: 10.1080/14660820310012745] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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12
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Kimoto H, Eto R, Abe M, Kato H, Araki T. Alterations of Glial Cells in the Mouse Hippocampus During Postnatal Development. Cell Mol Neurobiol 2009; 29:1181-9. [DOI: 10.1007/s10571-009-9412-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2009] [Accepted: 05/07/2009] [Indexed: 12/21/2022]
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13
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Spencer JL, Waters EM, Romeo RD, Wood GE, Milner TA, McEwen BS. Uncovering the mechanisms of estrogen effects on hippocampal function. Front Neuroendocrinol 2008; 29:219-37. [PMID: 18078984 PMCID: PMC2440702 DOI: 10.1016/j.yfrne.2007.08.006] [Citation(s) in RCA: 306] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Accepted: 08/14/2007] [Indexed: 01/06/2023]
Abstract
Estrogens have direct effects on the brain areas controlling cognition. One of the most studied of these regions is the dorsal hippocampal formation, which governs the formation of spatial and episodic memories. In laboratory animals, most investigators report that estrogen enhances synaptic plasticity and improves performance on hippocampal-dependent cognitive behaviors. This review summarizes work conducted in our laboratory and others toward identifying estrogen's actions in the hippocampal formation, and the mechanisms for these actions. Physiologic and pharmacologic estrogen affects cognitive behavior in mammals, which may be applicable to human health and disease. The effects of estrogen in the hippocampal formation that lead to modulation of hippocampal function include effects on cell morphology, synapse formation, signaling, and excitability that have been studied in laboratory mice, rats, and primates. Finally, estrogen may signal through both nuclear and extranuclear hippocampal estrogen receptors to achieve its downstream effects.
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Affiliation(s)
- Joanna L Spencer
- Harold and Margaret Milliken Hatch Laboratory of Neuroendocrinology, The Rockefeller University, 1300 York Avenue, New York, NY 10065, USA
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14
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Repeated estradiol administration alters different aspects of neurogenesis and cell death in the hippocampus of female, but not male, rats. Neuroscience 2008; 152:888-902. [PMID: 18353559 DOI: 10.1016/j.neuroscience.2007.10.071] [Citation(s) in RCA: 153] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2007] [Revised: 09/20/2007] [Accepted: 10/08/2007] [Indexed: 02/07/2023]
Abstract
Estradiol has been shown to have neuroprotective effects, and acute estradiol treatment enhances hippocampal neurogenesis in the female brain. However, little is known about the effects of repeated administration of estradiol on the female brain, or about the effects of estradiol on the male brain. Gonadectomized male and female adult rats were injected with 5-bromo-2-deoxyuridine (BrdU) (200 mg/kg), and then 24 h later were given subcutaneous injections of either estradiol benzoate (33 mug/kg) or vehicle daily for 15 days. On day 16, animals were perfused and the brains processed to examine cells expressing Ki-67 (cell proliferation), BrdU (cell survival), doublecortin (young neuron production), pyknotic morphology (cell death), activated caspase-3 (apoptosis), and Fluoro-Jade B (degenerating neurons) in the dentate gyrus. In female rats, repeated administration of estradiol decreased the survival of new neurons (independent of any effects on initial cell proliferation), slightly increased cell proliferation, and decreased overall cell death in the dentate gyrus. In male rats, repeated administration of estradiol had no significant effect on neurogenesis or cell death. We therefore demonstrate a clear sex difference in the response to estradiol of hippocampal neurogenesis and apoptosis in adult rats, with adult females being more responsive to the effects of estradiol than males.
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Lovekamp-Swan T, Glendenning ML, Schreihofer DA. A high soy diet enhances neurotropin receptor and Bcl-XL gene expression in the brains of ovariectomized female rats. Brain Res 2007; 1159:54-66. [PMID: 17582385 PMCID: PMC1995131 DOI: 10.1016/j.brainres.2007.05.026] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2006] [Revised: 04/25/2007] [Accepted: 05/20/2007] [Indexed: 10/23/2022]
Abstract
Estrogen is a powerful neuroprotective agent with the ability to induce trophic and antiapoptotic genes. However, concerns about negative overall health consequences of estrogen replacement after menopause have led to the adoption of other strategies to obtain estrogen's benefits in the brain, including the use of selective estrogen receptor modulators, high soy diets, or isoflavone supplements. This study sought to determine the ability of a high soy diet to induce neuroprotective gene expression in the female rat brain and compare the actions of soy with estrogen. Adult ovariectomized female rats were treated with 3 days of high dose estrogen or 2 weeks of a soy-free diet, a high soy diet, or chronic low dose estrogen. Different brain regions were microdissected and subjected to real time RT-PCR for neuroprotective genes previously shown to be estrogen-regulated. The principle findings are that a high soy diet led to the widespread increase in the mRNA for neurotropin receptors TrkA and p75-NTR, and the antiapoptotic Bcl-2 family member Bcl-X(L). Immunohistochemistry confirmed increases in both TrkA and Bcl-X(L). Chronic low dose estrogen mimicked some of these effects, but acute high dose estrogen did not. The effects of a high soy diet were particularly evident in the parietal cortex and hippocampus, two regions protected by estrogen in animal models of neurological disease and injury. These results suggest that a high soy diet may provide beneficial effects to the brain similar to low dose chronic estrogen treatment such as that used for postmenopausal hormone replacement.
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Affiliation(s)
- Tara Lovekamp-Swan
- Department of Physiology, Medical College of Georgia, 1120 15th Street, Augusta, GA 30912-3000
| | - Michele L. Glendenning
- Department of Physiology, Medical College of Georgia, 1120 15th Street, Augusta, GA 30912-3000
| | - Derek A. Schreihofer
- Department of Physiology, Medical College of Georgia, 1120 15th Street, Augusta, GA 30912-3000
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16
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McEwen BS, Milner TA. Hippocampal formation: shedding light on the influence of sex and stress on the brain. ACTA ACUST UNITED AC 2007; 55:343-55. [PMID: 17395265 PMCID: PMC2101766 DOI: 10.1016/j.brainresrev.2007.02.006] [Citation(s) in RCA: 145] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2006] [Revised: 02/12/2007] [Accepted: 02/20/2007] [Indexed: 02/05/2023]
Abstract
The hippocampus is a malleable brain region that responds to external agents such as hormones and stressors. Investigations that began in our laboratories with the Golgi technique and an appreciation of hippocampal neuroanatomy at the light and electron microscopic levels have led us down a path that has uncovered unexpected structural plasticity in the adult brain along with unanticipated cellular and molecular mechanisms of this plasticity and of hormone mediation of these effects. This chapter reviews the history of discoveries in our two laboratories involving the actions of estradiol and stress hormones on neuronal structure and function and then discusses the insight to hormone-brain interactions that this has engendered. These discoveries have led us to a new view of brain structural plasticity and the role and mechanism of steroid hormone action involving both genomic and non-genomic pathways. This new view is consistent with the predictions of Cajal in his book "The Structure of Ammon's horn", 1892.
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Affiliation(s)
- Bruce S. McEwen
- Harold and Margaret Milliken Hatch Laboratory of Neuroendocrinology, Rockefeller University, 1300 York Ave., New York, NY 10021
| | - Teresa A. Milner
- Harold and Margaret Milliken Hatch Laboratory of Neuroendocrinology, Rockefeller University, 1300 York Ave., New York, NY 10021
- Department of Neurology and Neuroscience, Weill-Cornell Medical College, 411 East 69th St., New York, NY 10021
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Stein DG. Sex differences in brain damage and recovery of function: experimental and clinical findings. PROGRESS IN BRAIN RESEARCH 2007; 161:339-51. [PMID: 17618989 DOI: 10.1016/s0079-6123(06)61024-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Until the last decade or so, there was very little systematic examination of sex differences in recovery from brain injury--most of the work was anecdotal or based on very small studies comparing males to females. This chapter reviews some of the physiological, morphological, and functional evidence for sex differences in response to brain injury across the spectrum of development. It also examines more recent data showing that fluctuations in hormonal status during the menstrual and estrous cycle can play a determining role in functional outcome in both normal and brain-injured females, and that these hormonal influences can be measured at both the cellular and behavioral levels.
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Affiliation(s)
- Donald G Stein
- Department of Emergency Medicine, Emory University School of Medicine, Atlanta, GA, USA.
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Abstract
Hormonal and locally produced steroids act in the nervous system as neuroendocrine regulators, as trophic factors and as neuromodulators and have a major impact on neural development and function. Glial cells play a prominent role in the local production of steroids and in the mediation of steroid effects on neurons and other glial cells. In this review, we examine the role of glia in the synthesis and metabolism of steroids and the functional implications of glial steroidogenesis. We analyze the mechanisms of steroid signaling on glia, including the role of nuclear receptors and the mechanisms of membrane and cytoplasmic signaling mediated by changes in intracellular calcium levels and activation of signaling kinases. Effects of steroids on functional parameters of glia, such as proliferation, myelin formation, metabolism, cytoskeletal reorganization, and gliosis are also reviewed, as well as the implications of steroid actions on glia for the regulation of synaptic function and connectivity, the regulation of neuroendocrine events, and the response of neural tissue to injury.
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Herrick SP, Waters EM, Drake CT, McEwen BS, Milner TA. Extranuclear estrogen receptor beta immunoreactivity is on doublecortin-containing cells in the adult and neonatal rat dentate gyrus. Brain Res 2006; 1121:46-58. [PMID: 17026970 DOI: 10.1016/j.brainres.2006.08.084] [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] [Received: 06/10/2006] [Revised: 08/03/2006] [Accepted: 08/22/2006] [Indexed: 12/17/2022]
Abstract
In adult female rats, estrogen receptor (ER) activation, particularly of ERbeta, promotes hippocampal neurogenesis. We previously reported that extranuclear ERbeta immunoreactivity (ir) in adult rats is on cellular profiles in or near the granule cell layer, which is the location of newly generated cells. During development, cells in or near the granule cell layer transiently express high levels of estrogen binding and nuclear ERs. Thus, we sought to determine if extranuclear ERbeta is in newly generated cells in adult and neonatal rat dentate gyrus. Sections from the dentate gyrus of adult proestrus or postnatal day 7 and 14 female rats were dual-labeled for ERbeta and the new-cell marker doublecortin (DCX) and examined by electron microscopy. DCX-containing neurons were found in the subgranular hilus in adult rats and were more widespread throughout the granule cell layer and hilus of neonatal rats. In both adults and neonatal rats, ERbeta immunoreactivity was found in a subset of DCX-labeled neurons. Electron microscopic examination of the adult dentate gyrus revealed that most perikarya with DCX-ir had the morphological characteristics of granule cells, although a few resembled interneurons. Dendrites with DCX-ir also were observed. In both adults and neonates, DCX-labeled neuronal perikarya and dendrites contained ERbeta-ir; ERbeta-ir usually was aggregated near the plasma membrane, mitochondria or endoplasmic reticula. ERbeta-ir was in glial profiles that apposed DCX-labeled perikarya and dendrites. These findings are consistent with data showing that estrogens can exert non-genomic effects directly and indirectly on newly generated cells in neonatal and adult rat dentate gyrus.
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Affiliation(s)
- Scott P Herrick
- Department of Neurology and Neuroscience, Weill-Cornell Medical College, New York, NY 10021, USA
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Shi Z, Arai KY, Jin W, Weng Q, Watanabe G, Suzuki AK, Taya K. Expression of Nerve Growth Factor and Its Receptors NTRK1 and TNFRSF1B Is Regulated by Estrogen and Progesterone in the Uteri of Golden Hamsters1. Biol Reprod 2006; 74:850-6. [PMID: 16436532 DOI: 10.1095/biolreprod.105.044917] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Experiments were conducted using female golden hamsters to identify the presence of nerve growth factor (NGF) and its receptors NTRK1 and TNFRSF1B in the uteri of female animals and regulation on their expression by estrogen and progesterone. NGF and its receptor NTRK1 were immunolocalized to luminal epithelial cells, glandular cells, and stromal cells. TNFRSF1B was immunolocalized in luminal epithelial and glandular cells, with no staining found in stromal cells of the uterine horns of normal cyclic golden hamsters. Strong immunostaining of NGF and its receptors NTRK1 and TNFRSF1B was observed in uteri on the day of proestrus as compared to the other stages of the estrous cycle. Results of immunoblot analysis of NGF revealed that there was a positive correlation between uterine NGF expression and plasma concentrations of estradiol-17beta. To clarify the effects of estrogen and progesterone on NGF, NTRK1, and TNFRSF1B expression, adult female golden hamsters were ovariectomized and treated with estradiol-17beta and/or progesterone. Immunoblot analysis and immunohistochemistry indicated that estradiol-17beta stimulated expression of NGF and its two receptors in the uterus. Treatment with progesterone also increased NGF and NTRK1 expression in the uterus. However, no additive effect of these steroids on expression of NGF and its receptors was observed. Changes in uterine weights induced by estradiol-17beta and/or progesterone showed the same profile with that of NGF, suggesting that a proliferative act of NGF may be involved in uterine growth. These results suggest that NGF may play important roles in action of steroids on uterine function.
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Affiliation(s)
- Zhanquan Shi
- Department of Basic Veterinary Science, The United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan
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Milner TA, Ayoola K, Drake CT, Herrick SP, Tabori NE, McEwen BS, Warrier S, Alves SE. Ultrastructural localization of estrogen receptor beta immunoreactivity in the rat hippocampal formation. J Comp Neurol 2006; 491:81-95. [PMID: 16127691 DOI: 10.1002/cne.20724] [Citation(s) in RCA: 302] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Several lines of evidence indicate that estrogen affects hippocampal synaptic plasticity through rapid nongenomic mechanisms, possibly by binding to plasma membrane estrogen receptors (ERs). We have previously shown that ERalpha immunoreactivity (ir) is in select interneuron nuclei and in several extranuclear locations, including dendritic spines and axon terminals, within the rat hippocampal formation (Milner et al., [2001] J Comp Neurol 429:355). The present study sought to determine the cellular and subcellular locations of ERbeta-ir. Coronal hippocampal sections from diestrus rats were immunolabeled with antibodies to ERbeta and examined by light and electron microscopy. By light microscopy, ERbeta-ir was primarily in the perikarya and proximal dendrites of pyramidal and granule cells. ERbeta-ir was also in a few nonprincipal cells and scattered nuclei in the ventral subiculum and CA3 region. Ultrastructural analysis revealed ERbeta-ir at several extranuclear sites in all hippocampal subregions. ERbeta-ir was affiliated with cytoplasmic organelles, especially endomembranes and mitochondria, and with plasma membranes primarily of principal cell perikarya and proximal dendrites. ERbeta-ir was in dendritic spines, many arising from pyramidal and granule cell dendrites. In both dendritic shafts and spines, ERbeta-ir was near the perisynaptic zone adjacent to synapses formed by unlabeled terminals. ERbeta-ir was in preterminal axons and axon terminals, associated with clusters of small, synaptic vesicles. ERbeta-labeled terminals formed both asymmetric and symmetric synapses with dendrites. ERbeta-ir also was detected in glial profiles. The cellular and subcellular localization of ERbeta-ir was generally similar to that of ERalpha, except that ERbeta was more extensively found at extranuclear sites. These results suggest that ERbeta may serve primarily as a nongenomic transducer of estrogen actions in the hippocampal formation.
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Affiliation(s)
- Teresa A Milner
- Division of Neurobiology, Department of Neurology and Neuroscience, Weill Medical College of Cornell University, New York 10021, USA.
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Aronica E, Ozbas-Gerçeker F, Redeker S, Ramkema M, Spliet WGM, van Rijen PC, Leenstra S, Gorter JA, Troost D. Expression and cellular distribution of high- and low-affinity neurotrophin receptors in malformations of cortical development. Acta Neuropathol 2004; 108:422-34. [PMID: 15375667 DOI: 10.1007/s00401-004-0906-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2004] [Revised: 06/28/2004] [Accepted: 06/28/2004] [Indexed: 12/01/2022]
Abstract
An increasing number of observations suggests an important and complex role for both high- (tyrosine kinase receptor, trk) and low- (p75) affinity neurotrophin receptors (NTRs) during development in human brain. In the present study, the cell-specific distribution of NTRs was studied in different developmental lesions, including focal cortical dysplasia (FCD, n = 15), ganglioglioma (GG, n = 15) and dysembryoplastic neuroepithelial tumors, (DNT, n = 10), from patients with medically intractable epilepsy. Lesional, perilesional, as well as normal brain regions were examined for the expression of trkA, trkB, trkC and p75(NTR) by immunocytochemistry. In normal postmortem human cortex, immunoreactivity (IR) for trk and p75(NTR) was mainly observed in pyramidal neurons, whereas no notable glial IR was found within the white matter. All three trk receptors were encountered in high levels in the neuronal component of the majority of FCD, GG and DNT specimens. Strong trkA, trkB and trkC IR was found in neurons of different size, including large dysplastic neurons and balloon cells in FCD cases. In contrast, p75(NTR) IR was observed in only a small number of neuronal cells, which also contain trk receptors. Glial cells with astrocytic morphology showed predominantly IR for trkA in FCD and GG specimens, whereas oligodendroglial-like cells in DNT showed predominently IR for trkB. P75(NTR) IR was observed in a population of cells of the microglial/macrophage lineage in both FCD and glioneuronal tumors. Taken together, our findings indicate that the neuronal and the glial components of malformations of cortical development express both high- and low-affinity NTRs. Further research is necessary to investigate how activation of these specific receptors could contribute to the development and the epileptogenicity of these developmental disorders.
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Affiliation(s)
- Eleonora Aronica
- Department of (Neuro)Pathology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
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23
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Ozbas-Gerçeker F, Gorter JA, Redeker S, Ramkema M, van der Valk P, Baayen JC, Ozgüç M, Saygi S, Soylemezoglu F, Akalin N, Troost D, Aronica E. Neurotrophin receptor immunoreactivity in the hippocampus of patients with mesial temporal lobe epilepsy. Neuropathol Appl Neurobiol 2004; 30:651-64. [PMID: 15541005 DOI: 10.1111/j.1365-2990.2004.00582.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Recent evidence supports a critical role of neurotrophins in the regulation of both neuronal survival and synaptic transmission during epileptogenesis. We have examined the immunohistochemical expression of high- (tyrosine kinase receptors, trk) and low-affinity (p75) neurotrophin receptors (NTRs) in the hippocampal specimens from 18 patients with chronic temporal lobe epilepsy [TLE; 14 patients with hippocampal sclerosis (HS) and four with focal lesions (tumours) not involving the hippocampus proper]. Nonepileptic autopsy brains (n = 6) and surgical specimens from tumour patients without epilepsy (n = 3) were used as controls. Immunoreactivity (IR) for the trk receptors (trkA, trkB, trkC) was detected in normal human brain within the pyramidal neurones of hippocampal cornus ammoni (CA) regions and in the dentate gyrus. There were no detectable differences in the neuronal trk IR patterns in the hippocampus between control and TLE cases with HS, except for a decrease in neuronal density in regions where cell death had occurred (CA1, CA3 and CA4). In contrast, a consistent increase in trkA IR was observed in reactive astrocytes in CA1 and dentate gyrus. The low-affinity p75 neurotrophin receptor (p75(NTR)) was expressed in low levels in postnatal normal hippocampus. In contrast, neuronal p75(NTR) IR was detected in 10/14 cases of HS in spared neurones within the CA and hilar regions of the hippocampus. Double labelling revealed that p75(NTR)-positive neurones also contain trk receptor IR. In six cases with prominent glial activation strong p75(NTR) IR was observed in microglial cells within the sclerotic hippocampus. The present results indicate that changes in NTR expression are still detectable in the hippocampus of patients with chronic TLE and involve both glial and neuronal cells. Reactive astrocytes were immunoreactive for trkA, whereas activated microglia cells were reactive for p75(NTR), suggesting different functions for specific NTRs in the development of reactive gliosis. Moreover, the increased expression of p75(NTR) in hippocampal neurones of TLE patients may critically influence the neuronal survival during the epileptogenic process.
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Affiliation(s)
- F Ozbas-Gerçeker
- Department of Medical Biology, Hacettepe University, Ankara, Turkey
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Azcoitia I, Sierra A, Veiga S, Garcia-Segura LM. Aromatase expression by reactive astroglia is neuroprotective. Ann N Y Acad Sci 2004; 1007:298-305. [PMID: 14993062 DOI: 10.1196/annals.1286.028] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The enzyme aromatase catalyzes the conversion of testosterone and other C19 steroids to estradiol. Under normal circumstances, the expression of aromatase in the central nervous system of mammals is restricted to neurons. However, the expression of the enzyme is induced in astrocytes in vitro by stressful stimuli. Furthermore, different types of brain injury induce in vivo the expression of aromatase in reactive astrocytes. The expression of aromatase by reactive astrocytes is neuroprotective, because the pharmacological inhibition of the enzyme in the brain exacerbates neuronal death after different forms of mild neurodegenerative stimuli that do not significantly affect neuronal survival under control conditions. These findings indicate that the induction of aromatase in reactive astrocytes, and the consecutive increase in the local production of estradiol in the brain at injured sites, may be an endogenous neural response to reduce the extent of neurodegenerative damage.
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Affiliation(s)
- Inigo Azcoitia
- Departamento de Biologïa Celular, Facultad de Biología, Universidad Complutense, E-28040 Madrid, Spain.
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25
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Abstract
Long relegated to the backwaters of neuroendocrinology, it is becoming increasingly apparent that glial cells of the central and peripheral nervous system are key participants because they are capable of both sending and receiving hormonal signals. Hormones are also a critical component of neuronal/glial cross talk, leading to neuromodulatory and neurotrophic actions under physiological and pathological conditions. In the peripheral nervous system, hormonal actions on Schwann cells and hormonal metabolites produced by these glial cells promote myelin formation and the remyelination and regeneration of injured nerves. In the central nervous system, glial cells participate in the hormonal regulation of synaptic function, synaptic plasticity, myelin formation, cognition, sleep, and the response of nervous tissue to injury. In addition, central glial cells participate in the regulation of hormonal secretion by hypothalamic neurons. Therefore, glial cells are a key element to understanding hormonal actions in the nervous system and the regulation of neuroendocrine events.
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Shetty AK, Zaman V, Shetty GA. Hippocampal neurotrophin levels in a kainate model of temporal lobe epilepsy: a lack of correlation between brain-derived neurotrophic factor content and progression of aberrant dentate mossy fiber sprouting. J Neurochem 2003; 87:147-59. [PMID: 12969262 DOI: 10.1046/j.1471-4159.2003.01979.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A significant upregulation of neurotrophins particularly brain-derived neurotrophic factor (BDNF) is believed to be involved in the initiation of epileptogenic changes such as the aberrant axonal sprouting and synaptic reorganization in the injured hippocampus. However, it is unknown which of the neurotrophins are upregulated during the peak period of aberrant mossy fiber sprouting in the chronically injured hippocampus. We measured chronic changes in the levels of BDNF, nerve growth factor (NGF) and neurotrophin-3 (NT-3) in the adult hippocampus using enzyme-linked immunosorbent assay (ELISA) after a unilateral intracerebroventricular administration of kainic acid (KA), a model of temporal lobe epilepsy. For comparison, neurotrophins were also measured from the control intact hippocampus. Further, to see the association between changes in neurotrophin levels and the progression of mossy fiber sprouting, chronic changes in the mossy fiber distribution within the dentate supragranular layer (DSGL) were quantified. In the KA-lesioned hippocampus, the neurotrophins BDNF and NGF were upregulated at 4 days post-lesion, in comparison to their levels in the intact hippocampus. However, the concentration of BDNF reached the baseline level at 45 days post-lesion and dramatically diminished at 120 days post-lesion. In contrast, the upregulation of NGF observed at 4 days post-lesion was sustained at both 45 days and 120 days post-lesion. The concentration of NT-3 was upregulated at 45 days post-lesion but remained comparable to baseline levels at 4 days and 120 days post-lesion. Interestingly, analysis of mossy fiber sprouting revealed that most of the aberrant sprouting in the lesioned hippocampus occurs between 45 days and 120 days post-lesion. Taken together, these results suggest that the period of robust mossy fiber sprouting does not correlate with the phase of post-lesion BDNF upregulation. Rather, it shows a relationship with the time of upregulation of neurotrophins NGF and NT-3.
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Affiliation(s)
- Ashok K Shetty
- Medical Research Service, Veterans Affairs Medical Center, Durham, North Carolina, USA.
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Oderfeld-Nowak B, Orzyłowska-Sliwińska O, Sołtys Z, Zaremba M, Januszewski S, Janeczko K, Mossakowski M. Concomitant up-regulation of astroglial high and low affinity nerve growth factor receptors in the CA1 hippocampal area following global transient cerebral ischemia in rat. Neuroscience 2003; 120:31-40. [PMID: 12849738 DOI: 10.1016/s0306-4522(03)00289-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We have examined the effect of global transient cerebral ischemia, evoked in rat by 10 min of cardiac arrest, upon the changes in the cellular expression of two nerve growth factor (NGF) receptors (TrkA and p75) in the hippocampus. We have used immunocytochemical procedures, including a quantitative analysis of staining, along with some quantitative morphological analyses. We have found, under ischemic conditions, a decrease of TrkA immunoreactivity in degenerating CA1 pyramidal neurons and in neuropil. On the other hand, a strong, ischemia-induced up-regulation of TrkA and p75 immunoreactivity was observed in the majority of reactive astroglia population in the adjacent CA1 hippocampal region. The colocalization of the two receptors in the same reactive astroglial cells was evidenced by double immunostaining and further supported by quantitative morphological analysis of TrkA and p75 immunoreactive glial cells. Our data implicate the involvement of NGF receptors in the postischemic regulation of astrocytic function; however, the lack of NGF receptor expression on some astrocytes suggests heterogeneity of astroglia population. Our results also indicate that the lack of neuroprotective action of astroglial NGF induced in the ischemic hippocampus [J Neurosci Res 41 (1995) 684; Acta Neurobiol Exp 57 (1997) 31; Neuroscience 91 (1999) 1027] is not caused by a paucity of NGF receptors but may rather be due to the counteraction of some proinflammatory substances, released simultaneously by glia cells. On the other hand, the up-regulated astroglial TrkA receptor may be an important target for exogenous NGF, which, as previously described [J Neurosci 11 (1991) 2914; Neurosci Lett 141 (1992) 161], exerts a neuroprotective effect in ischemia.
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Affiliation(s)
- B Oderfeld-Nowak
- Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteura Street, 02093 Warsaw, Poland.
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Soltys Z, Janeczko K, Orzyłowska-Sliwińska O, Zaremba M, Januszewski S, Oderfeld-Nowak B. Morphological transformations of cells immunopositive for GFAP, TrkA or p75 in the CA1 hippocampal area following transient global ischemia in the rat. A quantitative study. Brain Res 2003; 987:186-93. [PMID: 14499962 DOI: 10.1016/s0006-8993(03)03327-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Transient global ischemia induces intensive neuronal degeneration in the hippocampal CA1 pyramidal layer, accompanied by reactive transformation of glial cells. Previously, we have shown using the double immunostaining method that the NGF receptors (NGFR) p75 and TrkA are expressed mainly on subpopulations of GFAP+ astrocytes, and this expression increases progressively after ischemia. In the presented study, we analyzed quantitatively the morphological transformations of cells immunopositive for GFAP or NGF receptors in the stratum radiatum of the CA1 hippocampal area in different survival periods after ischemia, evoked by 10-min cardiac arrest in adult rats. In control brains, NGF receptors were expressed only on small cells with poorly ramified processes. After ischemia, the NGFR+ cells increased in size and morphological complexity (measured using fractal analysis). However, even 2 weeks after ischemia these cells did not reach the size and value of the fractal dimension typical of the largest GFAP+ astrocytes. Moreover, the reaction of NGFR+ cells was significantly delayed in comparison with the total astrocyte population. The obtained results suggest that NGF receptors are expressed mainly by immature astrocytes and ischemia induces the maturation of these cells.
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Affiliation(s)
- Z Soltys
- Department of Neuroanatomy, Institute of Zoology, Jagiellonian University, 6 Ingardena St., 30-060 Cracow, Poland
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Towart LA, Alves SE, Znamensky V, Hayashi S, McEwen BS, Milner TA. Subcellular relationships between cholinergic terminals and estrogen receptor-alpha in the dorsal hippocampus. J Comp Neurol 2003; 463:390-401. [PMID: 12836175 DOI: 10.1002/cne.10753] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Cholinergic septohippocampal neurons are affected by circulating estrogens. Previously, we found that extranuclear estrogen receptor-alpha (ERalpha) immunoreactivity in presynaptic profiles had an overlapping distribution with cholinergic afferents in the rat hippocampal formation. To determine the subcellular relationships between cholinergic presynaptic profiles and ERalpha, hippocampal sections were dually immunolabeled for vesicular acetylcholine transporter (VAChT) and ERalpha and examined by electron microscopy. Within the hippocampal formation, immunoreactivities for VAChT and ERalpha both were presynaptic, although their subcellular targeting was distinct. VAChT immunoreactivity was found exclusively within presynaptic profiles and was associated with small synaptic vesicles, which usually filled axon terminals. VAChT-labeled presynaptic profiles were most concentrated in stratum oriens of the hippocampal CA1 region and dentate inner molecular layer and hilus. In contrast, ERalpha immunoreactivity was found in clusters affiliated either with select vesicles or with the plasmalemma within preterminal axons and axon terminals. ERalpha-immunoreactive (IR) presynaptic profiles were more evenly distributed between hippocampal lamina than VAChT-IR profiles. Quantitative ultrastructural analysis revealed that VAChT-IR presynaptic profiles contained ERalpha immunoreactivity (ranging from 3% to 17%, depending on the lamina). Additionally, VAChT-IR presynaptic profiles apposed ERalpha-IR dendritic spines, presynaptic profiles, and glial profiles; many of the latter two types of profiles abutted unlabeled dendritic spines that received asymmetric (excitatory-type) synapses from unlabeled terminals. The presence of ERalpha immunoreactivity in cholinergic terminals suggests that estrogen could rapidly and directly affect the local release and/or uptake of acetylcholine. The affiliation of cholinergic terminals with excitatory terminals near ERalpha-labeled dendritic spines or glial profiles suggests that alterations in acetylcholine release could indirectly affect estrogen-modulated structural plasticity.
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Affiliation(s)
- Laura A Towart
- Division of Neurobiology, Department of Neurology and Neuroscience, Weill Medical College of Cornell University, New York, New York 10021, USA
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Ruiz-Ederra J, Hitchcock PF, Vecino E. Two classes of astrocytes in the adult human and pig retina in terms of their expression of high affinity NGF receptor (TrkA). Neurosci Lett 2003; 337:127-30. [PMID: 12536040 DOI: 10.1016/s0304-3940(02)01322-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Astrocytes have been implicated in axon guidance and synaptic regeneration in the retina and these processes involve activation of the high affinity nerve growth factor receptor, known as the tyrosine kinase A (TrkA) receptor. The purpose of the present study was to characterize the expression of TrkA in astrocytes of the adult pig and human retina. To this end, sections of human and pig retinas were immunolabeled with a combination of antibodies to glial fibrillary acidic protein (GFAP) and TrkA. Our study revealed that most of the GFAP-positive cells express TrkA, whereas a rare, novel subpopulation of astrocytes was found to be devoid of TrkA. Our results support the idea that astrocytes play an important neurotrophic role in the retina.
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Affiliation(s)
- Javier Ruiz-Ederra
- Departamento de Biología Celular e Histología, Facultad de Medicina y Odontología, Universidad del País Vasco, E-48940., Leioa, Spain
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Non-neuronal cells in the nervous system: sources and targets of neuroactive steroids. ADVANCES IN MOLECULAR AND CELL BIOLOGY 2003. [DOI: 10.1016/s1569-2558(03)31024-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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