1
|
Garcia-Segura LM, Méndez P, Arevalo MA, Azcoitia I. Neuroestradiol and neuronal development: Not an exclusive male tale anymore. Front Neuroendocrinol 2023; 71:101102. [PMID: 37689249 DOI: 10.1016/j.yfrne.2023.101102] [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: 07/26/2023] [Revised: 09/04/2023] [Accepted: 09/06/2023] [Indexed: 09/11/2023]
Abstract
The brain synthesizes a variety of neurosteroids, including neuroestradiol. Inhibition of neuroestradiol synthesis results in alterations in basic neurodevelopmental processes, such as neurogenesis, neuroblast migration, neuritogenesis and synaptogenesis. Although the neurodevelopmental actions of neuroestradiol are exerted in both sexes, some of them are sex-specific, such as the well characterized effects of neuroestradiol derived from the metabolism of testicular testosterone during critical periods of male brain development. In addition, recent findings have shown sex-specific actions of neuroestradiol on neuroblast migration, neuritic growth and synaptogenesis in females. Among other factors, the epigenetic regulation exerted by X linked genes, such as Kdm6a/Utx, may determine sex-specific actions of neuroestradiol in the female brain. This review evidences the impact of neuroestradiol on brain formation in both sexes and highlights the interaction of neural steriodogenesis, hormones and sex chromosomes in sex-specific brain development.
Collapse
Affiliation(s)
- Luis M Garcia-Segura
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Avenida Doctor Arce 37, 28002 Madrid, Spain; Centro de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto Nacional de Salud Carlos III, Madrid, Spain.
| | - Pablo Méndez
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Avenida Doctor Arce 37, 28002 Madrid, Spain
| | - M Angeles Arevalo
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Avenida Doctor Arce 37, 28002 Madrid, Spain; Centro de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto Nacional de Salud Carlos III, Madrid, Spain.
| | - Iñigo Azcoitia
- Centro de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto Nacional de Salud Carlos III, Madrid, Spain; Department of Cell Biology, Universidad Complutense de Madrid, C José Antonio Nováis 12, 28040 Madrid, Spain
| |
Collapse
|
2
|
Wilson C, Moyano AL, Cáceres A. Perspectives on Mechanisms Supporting Neuronal Polarity From Small Animals to Humans. Front Cell Dev Biol 2022; 10:878142. [PMID: 35517494 PMCID: PMC9062071 DOI: 10.3389/fcell.2022.878142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 04/04/2022] [Indexed: 11/23/2022] Open
Abstract
Axon-dendrite formation is a crucial milestone in the life history of neurons. During this process, historically referred as “the establishment of polarity,” newborn neurons undergo biochemical, morphological and functional transformations to generate the axonal and dendritic domains, which are the basis of neuronal wiring and connectivity. Since the implementation of primary cultures of rat hippocampal neurons by Gary Banker and Max Cowan in 1977, the community of neurobiologists has made significant achievements in decoding signals that trigger axo-dendritic specification. External and internal cues able to switch on/off signaling pathways controlling gene expression, protein stability, the assembly of the polarity complex (i.e., PAR3-PAR6-aPKC), cytoskeleton remodeling and vesicle trafficking contribute to shape the morphology of neurons. Currently, the culture of hippocampal neurons coexists with alternative model systems to study neuronal polarization in several species, from single-cell to whole-organisms. For instance, in vivo approaches using C. elegans and D. melanogaster, as well as in situ imaging in rodents, have refined our knowledge by incorporating new variables in the polarity equation, such as the influence of the tissue, glia-neuron interactions and three-dimensional development. Nowadays, we have the unique opportunity of studying neurons differentiated from human induced pluripotent stem cells (hiPSCs), and test hypotheses previously originated in small animals and propose new ones perhaps specific for humans. Thus, this article will attempt to review critical mechanisms controlling polarization compiled over decades, highlighting points to be considered in new experimental systems, such as hiPSC neurons and human brain organoids.
Collapse
|
3
|
Estradiol Induces Epithelial to Mesenchymal Transition of Human Glioblastoma Cells. Cells 2020; 9:cells9091930. [PMID: 32825553 PMCID: PMC7564468 DOI: 10.3390/cells9091930] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 08/02/2020] [Accepted: 08/11/2020] [Indexed: 02/07/2023] Open
Abstract
The mesenchymal phenotype of glioblastoma multiforme (GBM), the most frequent and malignant brain tumor, is associated with the worst prognosis. The epithelial–mesenchymal transition (EMT) is a cell plasticity mechanism involved in GBM malignancy. In this study, we determined 17β-estradiol (E2)-induced EMT by changes in cell morphology, expression of EMT markers, and cell migration and invasion assays in human GBM-derived cell lines. E2 (10 nM) modified the shape and size of GBM cells due to a reorganization of actin filaments. We evaluated EMT markers expression by RT-qPCR, Western blot, and immunofluorescence.We found that E2 upregulated the expression of the mesenchymal markers, vimentin, and N-cadherin. Scratch and transwell assays showed that E2 increased migration and invasion of GBM cells. The estrogen receptor-α (ER-α)-selective agonist 4,4’,4’’-(4-propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol (PPT, 10 nM) affected similarly to E2 in terms of the expression of EMT markers and cell migration, and the treatment with the ER-α antagonist methyl-piperidino-pyrazole (MPP, 1 μM) blocked E2 and PPT effects. ER-β-selective agonist diarylpropionitrile (DNP, 10 nM) and antagonist 4-[2-phenyl-5,7-bis(trifluoromethyl)pyrazole[1,5-a]pyrimidin-3-yl]phenol (PHTPP, 1 μM) showed no effects on EMT marker expression. These data suggest that E2 induces EMT activation through ER-α in human GBM-derived cells.
Collapse
|
4
|
Cisternas CD, Cabrera Zapata LE, Mir FR, Scerbo MJ, Arevalo MA, Garcia-Segura LM, Cambiasso MJ. Estradiol-dependent axogenesis and Ngn3 expression are determined by XY sex chromosome complement in hypothalamic neurons. Sci Rep 2020; 10:8223. [PMID: 32427857 PMCID: PMC7237695 DOI: 10.1038/s41598-020-65183-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 04/14/2020] [Indexed: 01/15/2023] Open
Abstract
Hypothalamic neurons show sex differences in neuritogenesis, female neurons have longer axons and higher levels of the neuritogenic factor neurogenin 3 (Ngn3) than male neurons in vitro. Moreover, the effect of 17-β-estradiol (E2) on axonal growth and Ngn3 expression is only found in male-derived neurons. To investigate whether sex chromosomes regulate these early sex differences in neuritogenesis by regulating the E2 effect on Ngn3, we evaluated the growth and differentiation of hypothalamic neurons derived from the “four core genotypes” mouse model, in which the factors of “gonadal sex” and “sex chromosome complement” are dissociated. We showed that sex differences in neurite outgrowth are determined by sex chromosome complement (XX > XY). Moreover, E2 increased the mRNA expression of Ngn3 and axonal length only in XY neurons. ERα/β expressions are regulated by sex chromosome complement; however, E2-effect on Ngn3 expression in XY neurons was only fully reproduced by PPT, a specific ligand of ERα, and prevented by MPP, a specific antagonist of ERα. Together our data indicate that sex chromosomes regulate early development of hypothalamic neurons by orchestrating not only sex differences in neuritogenesis, but also regulating the effect of E2 on Ngn3 expression through activation of ERα in hypothalamic neurons.
Collapse
Affiliation(s)
- Carla Daniela Cisternas
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina.,Departamento de Biología Bucal, Facultad de Odontología -Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Lucas Ezequiel Cabrera Zapata
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Franco Rafael Mir
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina
| | - María Julia Scerbo
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina
| | - María Angeles Arevalo
- Instituto Cajal, CSIC, Madrid, Spain.,Ciber de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
| | - Luis Miguel Garcia-Segura
- Instituto Cajal, CSIC, Madrid, Spain.,Ciber de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
| | - María Julia Cambiasso
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina. .,Departamento de Biología Bucal, Facultad de Odontología -Universidad Nacional de Córdoba, Córdoba, Argentina.
| |
Collapse
|
5
|
Sexually Dimorphic Effect of Genistein on Hypothalamic Neuronal Differentiation in Vitro. Int J Mol Sci 2019; 20:ijms20102465. [PMID: 31109056 PMCID: PMC6567056 DOI: 10.3390/ijms20102465] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Revised: 05/14/2019] [Accepted: 05/17/2019] [Indexed: 11/16/2022] Open
Abstract
Developmental actions of estradiol in the hypothalamus are well characterized. This hormone generates sex differences in the development of hypothalamic neuronal circuits controlling neuroendocrine events, feeding, growth, reproduction and behavior. In vitro, estradiol promotes sexually dimorphic effects on hypothalamic neuritogenesis. Previous studies have shown that developmental actions of the phytoestrogen genistein result in permanent sexually dimorphic effects in some behaviors and neural circuits in vivo. In the present study, we have explored if genistein, like estradiol, affects neuritogenesis in primary hypothalamic neurons and investigated the estrogen receptors implicated in this action. Hypothalamic neuronal cultures, obtained from male or female embryonic day 14 (E14) CD1 mice, were treated with genistein (0.1 µM, 0.5 µM or 1 µM) or vehicle. Under basal conditions, female neurons had longer primary neurites, higher number of secondary neurites and higher neuritic arborization compared to male neurons. The treatment with genistein increased neuritic arborization and the number of primary neurites and decreased the number of secondary neurites in female neurons, but not in male neurons. In contrast, genistein resulted in a significant increase in primary neuritic length in male neurons, but not in female neurons. The use of selective estrogen receptor antagonists suggests that estrogen receptor α, estrogen receptor β and G-protein-coupled estrogen receptors are involved in the neuritogenic action of genistein. In summary, these findings indicate that genistein exerts sexually dimorphic actions on the development of hypothalamic neurons, altering the normal pattern of sex differences in neuritogenesis.
Collapse
|
6
|
Cabrera Zapata LE, Bollo M, Cambiasso MJ. Estradiol-Mediated Axogenesis of Hypothalamic Neurons Requires ERK1/2 and Ryanodine Receptors-Dependent Intracellular Ca 2+ Rise in Male Rats. Front Cell Neurosci 2019; 13:122. [PMID: 31001087 PMCID: PMC6454002 DOI: 10.3389/fncel.2019.00122] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 03/12/2019] [Indexed: 12/12/2022] Open
Abstract
17β-estradiol (E2) induces axonal growth through extracellular signal-regulated kinase 1 and 2 (ERK1/2)-MAPK cascade in hypothalamic neurons of male rat embryos in vitro, but the mechanism that initiates these events is poorly understood. This study reports the intracellular Ca2+ increase that participates in the activation of ERK1/2 and axogenesis induced by E2. Hypothalamic neuron cultures were established from 16-day-old male rat embryos and fed with astroglia-conditioned media for 48 h. E2-induced ERK phosphorylation was completely abolished by a ryanodine receptor (RyR) inhibitor (ryanodine) and partially attenuated by an L-type voltage-gated Ca2+ channel (L-VGCC) blocker (nifedipine), an inositol-1,4,5-trisphosphate receptor (IP3R) inhibitor (2-APB), and a phospholipase C (PLC) inhibitor (U-73122). We also conducted Ca2+ imaging recording using primary cultured neurons. The results show that E2 rapidly induces an increase in cytosolic Ca2+, which often occurs in repetitive Ca2+ oscillations. This response was not observed in the absence of extracellular Ca2+ or with inhibitory ryanodine and was markedly reduced by nifedipine. E2-induced axonal growth was completely inhibited by ryanodine. In summary, the results suggest that Ca2+ mobilization from extracellular space as well as from the endoplasmic reticulum is necessary for E2-induced ERK1/2 activation and axogenesis. Understanding the mechanisms of brain estrogenic actions might contribute to develop novel estrogen-based therapies for neurodegenerative diseases.
Collapse
Affiliation(s)
- Lucas E Cabrera Zapata
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Mariana Bollo
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - María Julia Cambiasso
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET, Universidad Nacional de Córdoba, Córdoba, Argentina.,Cátedra de Biología Celular, Facultad de Odontología, Universidad Nacional de Córdoba, Córdoba, Argentina
| |
Collapse
|
7
|
Céspedes Rubio ÁE, Pérez-Alvarez MJ, Lapuente Chala C, Wandosell F. Sex steroid hormones as neuroprotective elements in ischemia models. J Endocrinol 2018; 237:R65-R81. [PMID: 29654072 DOI: 10.1530/joe-18-0129] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 03/19/2018] [Indexed: 12/14/2022]
Abstract
Among sex steroid hormones, progesterone and estradiol have a wide diversity of physiological activities that target the nervous system. Not only are they carried by the blood stream, but also they are locally synthesized in the brain and for this reason, estradiol and progesterone are considered 'neurosteroids'. The physiological actions of both hormones range from brain development and neurotransmission to aging, illustrating the importance of a deep understanding of their mechanisms of action. In this review, we summarize key roles that estradiol and progesterone play in the brain. As numerous reports have confirmed a substantial neuroprotective role for estradiol in models of neurodegenerative disease, we focus this review on traumatic brain injury and stroke models. We describe updated data from receptor and signaling events triggered by both hormones, with an emphasis on the mechanisms that have been reported as 'rapid' or 'cytoplasmic actions'. Data showing the therapeutic effects of the hormones, used alone or in combination, are also summarized, with a focus on rodent models of middle cerebral artery occlusion (MCAO). Finally, we draw attention to evidence that neuroprotection by both hormones might be due to a combination of 'cytoplasmic' and 'nuclear' signaling.
Collapse
Affiliation(s)
- Ángel Enrique Céspedes Rubio
- Departamento de Sanidad AnimalGrupo de Investigación en Enfermedades Neurodegenerativas, Universidad del Tolima, Ibagué, Colombia
| | - Maria José Pérez-Alvarez
- Departamento de Biología (Fisiología Animal)Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, Spain
- Centro de Biología Molecular 'Severo Ochoa'Departamento de Neuropatología Molecular CSIC-UAM, Madrid, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)Madrid, Spain
| | - Catalina Lapuente Chala
- Grupo de Investigación en Enfermedades NeurodegenerativasInvestigador Asociado Universidad del Tolima, Ibagué, Colombia
| | - Francisco Wandosell
- Centro de Biología Molecular 'Severo Ochoa'Departamento de Neuropatología Molecular CSIC-UAM, Madrid, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)Madrid, Spain
| |
Collapse
|
8
|
MYCN-amplified neuroblastoma maintains an aggressive and undifferentiated phenotype by deregulation of estrogen and NGF signaling. Proc Natl Acad Sci U S A 2018; 115:E1229-E1238. [PMID: 29374092 PMCID: PMC5819392 DOI: 10.1073/pnas.1710901115] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
High-risk neuroblastoma (NB), a cancer of the sympathetic nervous system, is challenging to treat. MYCN is frequently amplified in high-risk NB and is linked to an undifferentiated phenotype and poor prognosis. Estrogen and nerve growth factor (NGF) are inducers of neural differentiation, a process associated with a favorable disease. We show that MYCN suppresses estrogen receptor alpha (ERα) and thereby NGF signaling and neural differentiation. ERα overexpression is sufficient to interfere with different tumorigenic processes and tumor growth. In patients with NB, ERα expression correlates with several clinical markers for good prognosis. Importantly, not only ERα but also the majority of other nuclear hormone receptors are linked to favorable NB, suggesting a potential prognostic and therapeutic value for these proteins. Neuroblastoma (NB) is a remarkably heterogenic childhood tumor of the sympathetic nervous system with clinical behavior ranging from spontaneous regression to poorly differentiated tumors and metastasis. MYCN is amplified in 20% of cases and correlates with an undifferentiated, aggressive phenotype and poor prognosis. Estrogen receptor alpha (ERα) and the nerve growth factor (NGF) receptors TrkA and p75NTR are involved in neuronal differentiation and survival. We have previously shown that MYCN, via miR-18a, targets ERα in NB cells. Here, we demonstrate that interference with miR-18a or overexpression of ERα is sufficient to induce NGF signaling and to modulate both basal and NGF-induced neuronal differentiation in MYCN-amplified NB cells. Proteomic analysis confirmed an increase of neuronal features and showed that processes linked to tumor initiation and progression were inhibited upon ERα overexpression. Indeed, ectopic ERα expression was sufficient to inhibit metabolic activity and tumorigenic processes, including glycolysis, oxidative phosphorylation, cell viability, migration, and anchorage independent growth. Importantly, ERα overexpression reduced tumor burden in NB mouse models and high ERα levels were linked to improved survival in patients. In addition to ERα, several other nuclear hormone receptors (NHRs), including the glucocorticoid and the retinoic acid receptors, correlated with clinical markers for favorable and low-stage NB disease. Our data suggest that MYCN targets ERα and thereby NGF signaling to maintain an undifferentiated and aggressive phenotype. Notably, we identified the estrogen–NGF crosstalk, as well as a set of other NHRs, as potential prognostic markers and targets for therapeutic strategies against NB.
Collapse
|
9
|
Cambiasso MJ, Cisternas CD, Ruiz-Palmero I, Scerbo MJ, Arevalo MA, Azcoitia I, Garcia-Segura LM. Interaction of sex chromosome complement, gonadal hormones and neuronal steroid synthesis on the sexual differentiation of mammalian neurons. J Neurogenet 2017; 31:300-306. [DOI: 10.1080/01677063.2017.1390572] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Maria Julia Cambiasso
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina
- Departamento de Biología Bucal, Facultad de Odontología, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Carla Daniela Cisternas
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina
- Departamento de Biología Bucal, Facultad de Odontología, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Isabel Ruiz-Palmero
- CSIC, Instituto Cajal, Madrid, Spain
- Centro de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
| | - Maria Julia Scerbo
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina
- Departamento de Biología Bucal, Facultad de Odontología, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Maria Angeles Arevalo
- CSIC, Instituto Cajal, Madrid, Spain
- Centro de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
| | - Iñigo Azcoitia
- Centro de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
- Department of Cell Biology, Faculty of Biology, Universidad Complutense, Ciudad Universitaria, Madrid, Spain
| | - Luis M. Garcia-Segura
- CSIC, Instituto Cajal, Madrid, Spain
- Centro de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
| |
Collapse
|
10
|
Mir FR, Carrer HF, Cambiasso MJ. Sex differences in depolarizing actions of GABA A receptor activation in rat embryonic hypothalamic neurons. Eur J Neurosci 2016; 45:521-527. [PMID: 27888546 DOI: 10.1111/ejn.13467] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 10/27/2016] [Accepted: 11/02/2016] [Indexed: 11/28/2022]
Abstract
GABAA receptor activation exerts trophic actions in immature neurons through depolarization of resting membrane potential. The switch to its classical hyperpolarizing role is developmentally regulated. Previous results suggest that a hormonally biased sex difference exists at the onset of the switch in hypothalamic neurons. The aim of this work was to evaluate sex differences in GABAA receptor function of hypothalamic neurons before brain masculinization by gonadal hormones. Hypothalamic cells were obtained from embryonic day 16 male and female rat foetuses, 2 days before the peak of testosterone production by the foetal testis, and grown in vitro for 9 days. Whole-cell and perforated patch-clamp recordings were carried out in order to measure several electrophysiological parameters. Our results show that there are more male than female neurons responding with depolarization to muscimol. Additionally, among cells with depolarizing responses, males have higher and longer lasting responses than females. These results highlight the relevance of differences in neural cell sex irrespective of exposure to sex hormones.
Collapse
Affiliation(s)
- Franco R Mir
- Laboratory of Neurophysiology, Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Friuli 2434, 5016, Córdoba, Argentina
| | - Hugo F Carrer
- Laboratory of Neurophysiology, Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Friuli 2434, 5016, Córdoba, Argentina
| | - María J Cambiasso
- Laboratory of Neurophysiology, Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Friuli 2434, 5016, Córdoba, Argentina.,Departamento de Biología Bucal, Facultad de Odontología, Universidad Nacional de Córdoba, Córdoba, Argentina
| |
Collapse
|
11
|
Ruiz-Palmero I, Ortiz-Rodriguez A, Melcangi RC, Caruso D, Garcia-Segura LM, Rune GM, Arevalo MA. Oestradiol synthesized by female neurons generates sex differences in neuritogenesis. Sci Rep 2016; 6:31891. [PMID: 27553191 PMCID: PMC4995407 DOI: 10.1038/srep31891] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 07/29/2016] [Indexed: 12/04/2022] Open
Abstract
Testosterone produced by the foetal testis is converted by male neurons to oestradiol, which masculinizes neuronal morphology. Female neurons are known to synthesize oestradiol in absence of exogenous testosterone. However, the role of neuronal oestradiol on the differentiation of foetal female neurons is unknown. Here we show that, due to endogenous neuronal oestradiol synthesis, female hippocampal neurons have higher expression of the neuritogenic protein Neurogenin 3 and enhanced neuritogenesis than males. Exogenous application of testosterone or its metabolite dihydrotestosterone increases Neurogenin 3 expression and promotes neuritogenesis in males, but reduces these parameters in females. Together our data indicate that gonadal-independent oestradiol synthesis by female neurons participates in the generation of sex differences in hippocampal neuronal development.
Collapse
Affiliation(s)
- Isabel Ruiz-Palmero
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Avenida Doctor Arce 37, 28002 Madrid, Spain
| | - Ana Ortiz-Rodriguez
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Avenida Doctor Arce 37, 28002 Madrid, Spain
| | - Roberto Cosimo Melcangi
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Center of Excellence on Neurodegenerative Diseases, Università degli Studi di Milano, Via G. Balzaretti 9, 20133 Milan, Italy
| | - Donatella Caruso
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Center of Excellence on Neurodegenerative Diseases, Università degli Studi di Milano, Via G. Balzaretti 9, 20133 Milan, Italy
| | - Luis M Garcia-Segura
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Avenida Doctor Arce 37, 28002 Madrid, Spain
| | - Gabriele M Rune
- Institute of Neuroanatomy, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany
| | - Maria-Angeles Arevalo
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Avenida Doctor Arce 37, 28002 Madrid, Spain
| |
Collapse
|
12
|
Rossetti MF, Cambiasso MJ, Holschbach MA, Cabrera R. Oestrogens and Progestagens: Synthesis and Action in the Brain. J Neuroendocrinol 2016; 28. [PMID: 27306650 DOI: 10.1111/jne.12402] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 06/14/2016] [Accepted: 06/14/2016] [Indexed: 12/25/2022]
Abstract
When steroids, such as pregnenolone, progesterone and oestrogen, are synthesised de novo in neural tissues, they are more specifically referred to as neurosteroids. These neurosteroids bind specific receptors to promote essential brain functions. Pregnenolone supports cognition and protects mouse hippocampal cells against glutamate and amyloid peptide-induced cell death. Progesterone promotes myelination, spinogenesis, synaptogenesis, neuronal survival and dendritic growth. Allopregnanolone increases hippocampal neurogenesis, neuronal survival and cognitive functions. Oestrogens, such as oestradiol, regulate synaptic plasticity, reproductive behaviour, aggressive behaviour and learning. In addition, neurosteroids are neuroprotective in animal models of Alzheimer's disease, Parkinson's disease, brain injury and ageing. Using in situ hybridisation and/or immunohistochemistry, steroidogenic enzymes, including cytochrome P450 side-chain cleavage, 3β-hydroxysteroid dehydrogenase/Δ5-Δ4 isomerase, cytochrome P450arom, steroid 5α-reductase and 3α-hydroxysteroid dehydrogenase, have been detected in numerous brain regions, including the hippocampus, hypothalamus and cerebral cortex. In the present review, we summarise some of the studies related to the synthesis and function of oestrogens and progestagens in the central nervous system.
Collapse
Affiliation(s)
- M F Rossetti
- Departamento de Bioquímica Clínica, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, Santa Fe, Argentina
- Instituto de Salud y Ambiente del Litoral, CONICET-Universidad Nacional del Litoral, Santa Fe, Argentina
| | - M J Cambiasso
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina
- Departamento de Biología Bucal, Facultad de Odontología, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - M A Holschbach
- Biomedical Sciences, Colorado State University, Fort Collins, CO, USA
| | - R Cabrera
- Instituto de Investigaciones Biomédicas, INBIOMED-IMBECU-CONICET, Universidad de Mendoza, Mendoza, Argentina
| |
Collapse
|
13
|
The Role of Hypothalamic Neuropeptides in Neurogenesis and Neuritogenesis. Neural Plast 2016; 2016:3276383. [PMID: 26881105 PMCID: PMC4737468 DOI: 10.1155/2016/3276383] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Revised: 11/18/2015] [Accepted: 11/22/2015] [Indexed: 01/23/2023] Open
Abstract
The hypothalamus is a source of neural progenitor cells which give rise to different populations of specialized and differentiated cells during brain development. Newly formed neurons in the hypothalamus can synthesize and release various neuropeptides. Although term neuropeptide recently undergoes redefinition, small-size hypothalamic neuropeptides remain major signaling molecules mediating short- and long-term effects on brain development. They represent important factors in neurite growth and formation of neural circuits. There is evidence suggesting that the newly generated hypothalamic neurons may be involved in regulation of metabolism, energy balance, body weight, and social behavior as well. Here we review recent data on the role of hypothalamic neuropeptides in adult neurogenesis and neuritogenesis with special emphasis on the development of food intake and social behavior related brain circuits.
Collapse
|
14
|
Reddy RC, Amodei R, Estill CT, Stormshak F, Meaker M, Roselli CE. Effect of Testosterone on Neuronal Morphology and Neuritic Growth of Fetal Lamb Hypothalamus-Preoptic Area and Cerebral Cortex in Primary Culture. PLoS One 2015; 10:e0129521. [PMID: 26053052 PMCID: PMC4460015 DOI: 10.1371/journal.pone.0129521] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 05/08/2015] [Indexed: 12/22/2022] Open
Abstract
Testosterone plays an essential role in sexual differentiation of the male sheep brain. The ovine sexually dimorphic nucleus (oSDN), is 2 to 3 times larger in males than in females, and this sex difference is under the control of testosterone. The effect of testosterone on oSDN volume may result from enhanced expansion of soma areas and/or dendritic fields. To test this hypothesis, cells derived from the hypothalamus-preoptic area (HPOA) and cerebral cortex (CTX) of lamb fetuses were grown in primary culture to examine the direct morphological effects of testosterone on these cellular components. We found that within two days of plating, neurons derived from both the HPOA and CTX extend neuritic processes and express androgen receptors and aromatase immunoreactivity. Both treated and control neurites continue to grow and branch with increasing time in culture. Treatment with testosterone (10 nM) for 3 days significantly (P < 0.05) increased both total neurite outgrowth (35%) and soma size (8%) in the HPOA and outgrowth (21%) and number of branch points (33%) in the CTX. These findings indicate that testosterone-induced somal enlargement and neurite outgrowth in fetal lamb neurons may contribute to the development of a fully masculine sheep brain.
Collapse
Affiliation(s)
- Radhika C. Reddy
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Rebecka Amodei
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Charles T. Estill
- Department of Animal and Rangeland Sciences, Oregon State University, Corvallis, Oregon, United States of America
- Department of Clinical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, Oregon, United States of America
| | - Fred Stormshak
- Department of Animal and Rangeland Sciences, Oregon State University, Corvallis, Oregon, United States of America
| | - Mary Meaker
- Department of Animal and Rangeland Sciences, Oregon State University, Corvallis, Oregon, United States of America
| | - Charles E. Roselli
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon, United States of America
- * E-mail:
| |
Collapse
|
15
|
Hansberg-Pastor V, González-Arenas A, Piña-Medina AG, Camacho-Arroyo I. Sex Hormones Regulate Cytoskeletal Proteins Involved in Brain Plasticity. Front Psychiatry 2015; 6:165. [PMID: 26635640 PMCID: PMC4653291 DOI: 10.3389/fpsyt.2015.00165] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 11/02/2015] [Indexed: 01/22/2023] Open
Abstract
In the brain of female mammals, including humans, a number of physiological and behavioral changes occur as a result of sex hormone exposure. Estradiol and progesterone regulate several brain functions, including learning and memory. Sex hormones contribute to shape the central nervous system by modulating the formation and turnover of the interconnections between neurons as well as controlling the function of glial cells. The dynamics of neuron and glial cells morphology depends on the cytoskeleton and its associated proteins. Cytoskeletal proteins are necessary to form neuronal dendrites and dendritic spines, as well as to regulate the diverse functions in astrocytes. The expression pattern of proteins, such as actin, microtubule-associated protein 2, Tau, and glial fibrillary acidic protein, changes in a tissue-specific manner in the brain, particularly when variations in sex hormone levels occur during the estrous or menstrual cycles or pregnancy. Here, we review the changes in structure and organization of neurons and glial cells that require the participation of cytoskeletal proteins whose expression and activity are regulated by estradiol and progesterone.
Collapse
Affiliation(s)
- Valeria Hansberg-Pastor
- Departamento de Biología, Facultad de Química, Universidad Nacional Autónoma de México , Mexico City , Mexico
| | - Aliesha González-Arenas
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México , Mexico City , Mexico
| | - Ana Gabriela Piña-Medina
- Unidad de Investigación en Reproducción Humana, Instituto Nacional de Perinatología-Facultad de Química, Universidad Nacional Autónoma de México , Mexico City , Mexico
| | - Ignacio Camacho-Arroyo
- Unidad de Investigación en Reproducción Humana, Instituto Nacional de Perinatología-Facultad de Química, Universidad Nacional Autónoma de México , Mexico City , Mexico
| |
Collapse
|
16
|
Kranz GS, Hahn A, Kaufmann U, Küblböck M, Hummer A, Ganger S, Seiger R, Winkler D, Swaab DF, Windischberger C, Kasper S, Lanzenberger R. White matter microstructure in transsexuals and controls investigated by diffusion tensor imaging. J Neurosci 2014; 34:15466-75. [PMID: 25392513 PMCID: PMC4699258 DOI: 10.1523/jneurosci.2488-14.2014] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Revised: 09/16/2014] [Accepted: 10/02/2014] [Indexed: 12/22/2022] Open
Abstract
Biological causes underpinning the well known gender dimorphisms in human behavior, cognition, and emotion have received increased attention in recent years. The advent of diffusion-weighted magnetic resonance imaging has permitted the investigation of the white matter microstructure in unprecedented detail. Here, we aimed to study the potential influences of biological sex, gender identity, sex hormones, and sexual orientation on white matter microstructure by investigating transsexuals and healthy controls using diffusion tensor imaging (DTI). Twenty-three female-to-male (FtM) and 21 male-to-female (MtF) transsexuals, as well as 23 female (FC) and 22 male (MC) controls underwent DTI at 3 tesla. Fractional anisotropy, axial, radial, and mean diffusivity were calculated using tract-based spatial statistics (TBSS) and fiber tractography. Results showed widespread significant differences in mean diffusivity between groups in almost all white matter tracts. FCs had highest mean diffusivities, followed by FtM transsexuals with lower values, MtF transsexuals with further reduced values, and MCs with lowest values. Investigating axial and radial diffusivities showed that a transition in axial diffusivity accounted for mean diffusivity results. No significant differences in fractional anisotropy maps were found between groups. Plasma testosterone levels were strongly correlated with mean, axial, and radial diffusivities. However, controlling for individual estradiol, testosterone, or progesterone plasma levels or for subjects' sexual orientation did not change group differences. Our data harmonize with the hypothesis that fiber tract development is influenced by the hormonal environment during late prenatal and early postnatal brain development.
Collapse
Affiliation(s)
| | | | | | - Martin Küblböck
- MR Centre of Excellence, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, 1090 Vienna, Austria, and
| | - Allan Hummer
- MR Centre of Excellence, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, 1090 Vienna, Austria, and
| | | | - Rene Seiger
- Departments of Psychiatry and Psychotherapy and
| | | | - Dick F Swaab
- Netherlands Institute for Neuroscience, An Institute of the Royal Netherlands Academy of Arts and Sciences, 1105 BA Amsterdam, The Netherlands
| | - Christian Windischberger
- MR Centre of Excellence, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, 1090 Vienna, Austria, and
| | | | | |
Collapse
|
17
|
Scerbo MJ, Freire-Regatillo A, Cisternas CD, Brunotto M, Arevalo MA, Garcia-Segura LM, Cambiasso MJ. Neurogenin 3 mediates sex chromosome effects on the generation of sex differences in hypothalamic neuronal development. Front Cell Neurosci 2014; 8:188. [PMID: 25071448 PMCID: PMC4086225 DOI: 10.3389/fncel.2014.00188] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 06/19/2014] [Indexed: 01/01/2023] Open
Abstract
The organizational action of testosterone during critical periods of development is the cause of numerous sex differences in the brain. However, sex differences in neuritogenesis have been detected in primary neuronal hypothalamic cultures prepared before the peak of testosterone production by fetal testis. In the present study we assessed the hypothesis of that cell-autonomous action of sex chromosomes can differentially regulate the expression of the neuritogenic gene neurogenin 3 (Ngn3) in male and female hypothalamic neurons, generating sex differences in neuronal development. Neuronal cultures were prepared from male and female E14 mouse hypothalami, before the fetal peak of testosterone. Female neurons showed enhanced neuritogenesis and higher expression of Ngn3 than male neurons. The silencing of Ngn3 abolished sex differences in neuritogenesis, decreasing the differentiation of female neurons. The sex difference in Ngn3 expression was determined by sex chromosomes, as demonstrated using the four core genotypes mouse model, in which a spontaneous deletion of the testis-determining gene Sry from the Y chromosome was combined with the insertion of the Sry gene onto an autosome. In addition, the expression of Ngn3, which is also known to mediate the neuritogenic actions of estradiol, was increased in the cultures treated with the hormone, but only in those from male embryos. Furthermore, the hormone reversed the sex differences in neuritogenesis promoting the differentiation of male neurons. These findings indicate that Ngn3 mediates both cell-autonomous actions of sex chromosomes and hormonal effects on neuritogenesis.
Collapse
Affiliation(s)
- María J Scerbo
- Laboratory of Neurophysiology, Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET - Universidad Nacional de Córdoba Córdoba, Argentina
| | | | - Carla D Cisternas
- Laboratory of Neurophysiology, Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET - Universidad Nacional de Córdoba Córdoba, Argentina ; Departamento de Biología Bucal, Facultad de Odontología - Universidad Nacional de Córdoba Córdoba, Argentina
| | - Mabel Brunotto
- Departamento de Biología Bucal, Facultad de Odontología - Universidad Nacional de Córdoba Córdoba, Argentina
| | - Maria A Arevalo
- Instituto Cajal, Consejo Superior de Investigaciones Científicas Madrid, Spain
| | | | - María J Cambiasso
- Laboratory of Neurophysiology, Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET - Universidad Nacional de Córdoba Córdoba, Argentina ; Departamento de Biología Bucal, Facultad de Odontología - Universidad Nacional de Córdoba Córdoba, Argentina
| |
Collapse
|
18
|
Reddy R, Estill C, Meaker M, Stormshak F, Roselli CE. Sex differences in expression of oestrogen receptor α but not androgen receptor mRNAs in the foetal lamb brain. J Neuroendocrinol 2014; 26:321-8. [PMID: 24730418 PMCID: PMC4071168 DOI: 10.1111/jne.12152] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Revised: 03/12/2014] [Accepted: 03/16/2014] [Indexed: 11/26/2022]
Abstract
Gonadal steroid hormones play important roles during critical periods of development to organise brain structures that control sexually dimorphic neuroendocrine responses and behaviours. Specific receptors for androgens and oestrogens must be expressed at appropriate times during development to mediate these processes. The present study was performed to test for sex differences in the relative expression of oestrogen receptor (ER)α and androgen receptor (AR) mRNA during the window of time in gestation that is critical for behavioural masculinisation and differentiation of the ovine sexually dimorphic nucleus (oSDN) in the sheep. In addition, we examined whether ERα and AR mRNA expression is localised within the nascent oSDN and could be involved in its development. Using the quantitative real-time polymerase chain reaction, we found that females expressed more ERα mRNA than males in medial preoptic area and medial basal hypothalamus during the mid-gestational critical period for brain sexual differentiation. No sex differences were found for AR mRNA in any tissue examined or for ERα in amygdala and frontal cortex. Using radioactive in situ hybridisation, we found that the distributions of ERα and AR mRNA overlapped with aromatase mRNA, which delineates the boundaries of the developing oSDN and identifies this nucleus as a target for both androgens and oestrogens. These data demonstrate that the transcriptional machinery for synthesising gonadal steroid receptors is functional in the foetal lamb brain during the critical period for sexual differentiation and suggest that possible mechanisms for establishing dimorphisms controlled by gonadal steroids may exist at the level of steroid hormone receptor expression.
Collapse
Affiliation(s)
- Radhika Reddy
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, OR 97239-3098
| | - Charles Estill
- College of Veterinary Medicine Oregon State University, Corvallis, OR 97331-4501
| | - Mary Meaker
- Department of Animal and Rangeland Sciences, Oregon State University, Corvallis, OR 97331-4501
| | - Fred Stormshak
- Department of Animal and Rangeland Sciences, Oregon State University, Corvallis, OR 97331-4501
| | - Charles E. Roselli
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, OR 97239-3098
- Department of Animal and Rangeland Sciences, Oregon State University, Corvallis, OR 97331-4501
| |
Collapse
|
19
|
Billack B, Serio R, Silva I, Kinsley CH. Epigenetic changes brought about by perinatal stressors: A brief review of the literature. J Pharmacol Toxicol Methods 2012; 66:221-31. [DOI: 10.1016/j.vascn.2012.08.169] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Revised: 07/25/2012] [Accepted: 08/28/2012] [Indexed: 12/27/2022]
|
20
|
Arevalo MA, Ruiz-Palmero I, Scerbo MJ, Acaz-Fonseca E, Cambiasso MJ, Garcia-Segura LM. Molecular mechanisms involved in the regulation of neuritogenesis by estradiol: Recent advances. J Steroid Biochem Mol Biol 2012; 131:52-6. [PMID: 21971420 DOI: 10.1016/j.jsbmb.2011.09.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Revised: 09/19/2011] [Accepted: 09/21/2011] [Indexed: 12/13/2022]
Abstract
This review analyzes the signaling mechanisms activated by estradiol to regulate neuritogenesis in several neuronal populations. Estradiol regulates axogenesis by the activation of the mitogen activated protein kinase (MAPK) cascade through estrogen receptor α located in the plasma membrane. In addition, estradiol regulates MAPK signaling via the activation of protein kinase C and by increasing the expression of brain derived neurotrophic factor and tyrosine kinase receptor B. Estradiol also interacts with the signaling of insulin-like growth factor-I receptor through estrogen receptor α, modulating the phosphoinositide-3 kinase signaling pathway, which contributes to the stabilization of microtubules. Finally, estradiol modulates dendritogenesis by the inhibition of Notch signaling, by a mechanism that, at least in hippocampal neurons, is mediated by G-protein coupled receptor 30. This article is part of a Special Issue entitled 'Neurosteroids'.
Collapse
|
21
|
Kipp M, Amor S, Krauth R, Beyer C. Multiple sclerosis: neuroprotective alliance of estrogen-progesterone and gender. Front Neuroendocrinol 2012; 33:1-16. [PMID: 22289667 DOI: 10.1016/j.yfrne.2012.01.001] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Revised: 12/19/2011] [Accepted: 01/04/2012] [Indexed: 12/19/2022]
Abstract
The potential of 17β-estradiol and progesterone as neuroprotective factors is well-recognized. Persuasive data comes from in vitro and animal models reflecting a wide range of CNS disorders. These studies have endeavored to translate findings into human therapies. Nonetheless, few human studies show promising results. Evidence for neuroprotection was obtained in multiple sclerosis (MS) patients. This chronic inflammatory and demyelinating disease shows a female-to-male gender prevalence and disturbances in sex steroid production. In MS-related animal models, steroids ameliorate symptoms and protect from demyelination and neuronal damage. Both hormones operate in dampening central and brain-intrinsic immune responses and regulating local growth factor supply, oligodendrocyte and astrocyte function. This complex modulation of cell physiology and system stabilization requires the gamut of steroid-dependent signaling pathways. The identification of molecular and cellular targets of sex steroids and the understanding of cell-cell interactions in the pathogenesis will offer promise of novel therapy strategies.
Collapse
Affiliation(s)
- Markus Kipp
- Institute of Neuroanatomy, RWTH Aachen University, 52074 Aachen, Germany
| | | | | | | |
Collapse
|
22
|
Gerecke KM, Kishore R, Jasnow A, Quadros-Menella P, Parker S, Kozub FJ, Lambert KG, Kinsley CH. Alterations of sex-typical microanatomy: prenatal stress modifies the structure of medial preoptic area neurons in rats. Dev Psychobiol 2011; 54:16-27. [PMID: 21656762 DOI: 10.1002/dev.20570] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Accepted: 04/26/2011] [Indexed: 11/06/2022]
Abstract
Prenatal stress disrupts normal sexual differentiation and behavior with concomitant alterations in brain development; however, its effects on the cytoarchitecture of neurons in the sexually dimorphic medial preoptic area (mPOA) of the hypothalamus is not known. Morphometric analysis of the mPOA of adult rats showed sex differences as neurons from control females had significantly greater numbers of basal dendritic branches and cumulative basal dendritic length as compared to control male neurons. Prenatal stress significantly altered these sexual dimorphisms, as prenatally stressed (P-S) males had increased measures of cell body area, perimeter, cumulative basal dendritic length, and branch point numbers as compared to control males. Prenatal stress also altered the cytoarchitecture in the female mPOA neurons as P-S female neurons had significantly greater measures for primary dendritic branch number and a trend towards significance for several additional measures as compared to control females. Therefore, there are significant effects of both sex and prenatal stress on neuronal architecture in the mPOA that may help to explain the well-documented alterations in reproductive behaviors observed in P-S animals.
Collapse
Affiliation(s)
- Kim M Gerecke
- Department of Psychology, Rhodes College, 2000 N. Parkway, Memphis, TN 38112, USA.
| | | | | | | | | | | | | | | |
Collapse
|
23
|
Yang IH, Co CC, Ho CC. Controlling neurite outgrowth with patterned substrates. J Biomed Mater Res A 2011; 97:451-6. [PMID: 21484989 DOI: 10.1002/jbm.a.33082] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Revised: 01/05/2011] [Accepted: 02/03/2011] [Indexed: 11/05/2022]
Abstract
In vivo, neurons form neurites, one of which develops into the axon while others become dendrites. While this neuritogenesis process is well programmed in vivo, there are limited methods to control the number and location of neurite extension in vitro. Here we report a method to control neuritogenesis by confining neurons in specific regions using cell resistant poly(oligoethyleneglycol methacrylate-co-methacrylic acid (OEGMA-co-MA)) or poly(ethyleneglycol-block-lactic acid) PEG-PLA. Line patterned substrates reduce multiple extension of neurites and stimulate bi-directional neurite budding for PC12 and cortical neurons. PC12 cells on 20 and 30 μm line patterns extended one neurite in each direction along the line pattern while cortical neuron on 20 and 30 μm line patterns extended one or two neurites in each direction along the line pattern. Statistical analysis of neurite lengths revealed that PC12 cells and cortical neurons on line patterns extend longer neurites. The ability to guide formation of neurites on patterned substrates is useful for generating neural networks and promoting neurite elongation.
Collapse
Affiliation(s)
- In Hong Yang
- Department of Chemical and Materials Engineering University of Cincinnati Cincinnati, Ohio 45221, USA
| | | | | |
Collapse
|
24
|
Sex-dependent and region-specific changes in TrkB signaling in BDNF heterozygous mice. Brain Res 2011; 1384:51-60. [DOI: 10.1016/j.brainres.2011.01.060] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Revised: 01/17/2011] [Accepted: 01/19/2011] [Indexed: 12/11/2022]
|
25
|
Arevalo MA, Ruiz-Palmero I, Simon-Areces J, Acaz-Fonseca E, Azcoitia I, Garcia-Segura LM. Estradiol meets notch signaling in developing neurons. Front Endocrinol (Lausanne) 2011; 2:21. [PMID: 22654797 PMCID: PMC3356013 DOI: 10.3389/fendo.2011.00021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Accepted: 07/31/2011] [Indexed: 01/04/2023] Open
Abstract
The transmembrane receptor Notch, a master developmental regulator, controls gliogenesis, neurogenesis, and neurite development in the nervous system. Estradiol, acting as a hormonal signal or as a neurosteroid, also regulates these developmental processes. Here we review recent evidence indicating that estradiol and Notch signaling interact in developing hippocampal neurons by a mechanism involving the putative membrane receptor G protein-coupled receptor 30. This interaction is relevant for the control of neuronal differentiation, since the downregulation of Notch signaling by estradiol results in the upregulation of neurogenin 3, which in turn promotes dendritogenesis.
Collapse
Affiliation(s)
| | - Isabel Ruiz-Palmero
- Instituto Cajal, Consejo Superior de Investigaciones CientíficasMadrid, Spain
| | - Julia Simon-Areces
- Instituto Cajal, Consejo Superior de Investigaciones CientíficasMadrid, Spain
| | | | - Iñigo Azcoitia
- Facultad de Biología, Biología Celular, Universidad Complutense de MadridMadrid, Spain
| | - Luis Miguel Garcia-Segura
- Instituto Cajal, Consejo Superior de Investigaciones CientíficasMadrid, Spain
- *Correspondence: Luis Miguel Garcia-Segura, Instituto Cajal, Consejo Superior de Investigaciones Científicas, Avenida Doctor Arce 37, E-28002 Madrid, Spain. e-mail:
| |
Collapse
|
26
|
Gorosito SV, Cambiasso MJ. Axogenic effect of estrogen in male rat hypothalamic neurons involves Ca(2+), protein kinase C, and extracellular signal-regulated kinase signaling. J Neurosci Res 2008; 86:145-57. [PMID: 17722067 DOI: 10.1002/jnr.21466] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
17-beta-Estradiol (E2) stimulates the growth of axons in male-derived hypothalamic neurons in vitro. This effect is not exerted through the classical intracellular estrogen receptor (ER) but depends on a membrane mechanism involving TrkB. In the present study, we investigate the intracellular signaling cascade that mediates the axogenic effect of E2. Treatment with an intracellular Ca(2+) chelator, a Ca(2+)-dependent protein kinase C (PKC) inhibitor, or two specific inhibitors of extracellular signal-regulated kinases (ERK) mitogen-activated protein kinases (MAPK) completely inhibited the E2-induced axogenesis. E2 and the membrane-impermeant construct E2BSA rapidly induced phosphorylation of ERK, which was blocked by the specific inhibitor of the ERK pathway UO126 but not by the ER antagonist ICI 182,780. Decrease of intracellular free Ca(2+) or disruption of PKC activation by Ro 32-0432 attenuated ERK activation, indicating the confluence of signals in the MAPK pathway. Subcellular analysis of ERK demonstrated that the phospho-ERK signal is augmented in the nucleus after 15 min of E2 stimulation. We have also shown that E2 increased phosphorylation of CREB via ERK signaling. In summary, this study demonstrates that E2, probably via a membrane-associated receptor, induces axonal growth by activating CREB phosphorylation through ERK signaling by a mechanism involving Ca(2+) and PKC activation.
Collapse
Affiliation(s)
- S V Gorosito
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET, Córdoba, Argentina
| | | |
Collapse
|
27
|
Yokosuka M, Ohtani-Kaneko R, Yamashita K, Muraoka D, Kuroda Y, Watanabe C. Estrogen and environmental estrogenic chemicals exert developmental effects on rat hypothalamic neurons and glias. Toxicol In Vitro 2007; 22:1-9. [PMID: 17761398 DOI: 10.1016/j.tiv.2007.07.003] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2007] [Revised: 06/21/2007] [Accepted: 07/05/2007] [Indexed: 11/18/2022]
Abstract
We investigated effects of 17beta-estradiol (E(2)) and endocrine disrupters, nonylphenol (NP) and bisphenol-A (BPA), focusing on the neuronal development in cultures of fetal rat hypothalamic cells. We applied different concentrations of E(2), NP or BPA to the cultured hypothalamic cells and observed their effects on dendritic and synaptic development by immunocytochemistry using anti-microtubule associated protein-2 (MAP2) and anti-synapsin I antibodies, respectively. Administration of E(2) for 7 days affected MAP2-positive area as well as synapsin I-positive area. NP and BPA also influenced neuronal developments. The significant increase both in MAP2- and synapsin I-positive areas was observed at 10 and/or 100 nM of them, while 1 microM of them reduced the positive areas. Synaptic densities calculated from synapsin I-positive area/MAP2-positive area were not constant among different doses of three chemicals, but increased at 10 and/or 100 nM and decreased at 1 microM. Furthermore, immunostaining of NP-treated cells with the antibody against glial fibrillary acidic protein (GFAP) revealed that glial development was similarly influenced by NP. Therefore, the present results demonstrated that not only E(2) but also the environmental estrogenic chemicals, NP and BPA, affect development of fetal rat hypothalamic cells in vitro.
Collapse
Affiliation(s)
- Makoto Yokosuka
- Laboratory for Animal Neuroscience, Nippon Veterinary and Life Science University, 1-7-1 Kyonancho, Musashino, Tokyo 180-8602, Japan
| | | | | | | | | | | |
Collapse
|
28
|
Struble RG, Nathan BP, Cady C, Cheng X, McAsey M. Estradiol regulation of astroglia and apolipoprotein E: an important role in neuronal regeneration. Exp Gerontol 2006; 42:54-63. [PMID: 16837159 DOI: 10.1016/j.exger.2006.05.013] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2006] [Revised: 05/17/2006] [Accepted: 05/18/2006] [Indexed: 11/17/2022]
Abstract
The effects of ovarian hormone on neuronal growth and function are well known. However, equally important, but often neglected, are ovarian hormone effects on glia. Our in vivo and in vitro studies show that estradiol modifies both neuronal growth and glial activity and these effects are tightly linked. Estradiol stimulates neurite growth and the release of the glial apolipoprotein E (apoE) in culture studies. Estradiol-stimulated neurite growth in these cultures requires apoE. Estradiol replacement in ovariectomized mice transiently increases the expression of apoE, the low density lipoprotein receptor related protein (LRP) and synaptophysin throughout the brain. Continuous estradiol replacement over two months loses effect on apoE, LRP, and synaptophysin and suppresses reactive gliosis. Estrous cycle variation of glial activation (GFAP) and apoE are not identical. We propose that estradiol (and other ovarian hormones) functions as a zeitgeber to co-ordinate neuronal-glial interactions. Co-ordination assures temporally appropriate excitatory and inhibitory interactions between glia and neurons. With aging and the loss of ovarian cyclicity, some of this co-ordination must be diminished. These observations present significant clinical implications. Approaches to hormone therapy (HT), for diminishing the risk of chronic neurological diseases, need to consider the temporal nature of ovarian hormones in brain repair and plasticity. Moreover, approaches must consider apoE genotype. The neuroprotective effects of HT in numerous chronic age-related diseases may represent effective co-ordination of repair processes rather than direct disease-specific actions. Moreover, the role of glial-derived proteins in neuroprotection should not be ignored.
Collapse
Affiliation(s)
- Robert G Struble
- Department of Neurology and Center for Alzheimer Disease, Southern Illinois University School of Medicine, Springfield, IL 62794, USA.
| | | | | | | | | |
Collapse
|
29
|
Saenz C, Dominguez R, de Lacalle S. Estrogen contributes to structural recovery after a lesion. Neurosci Lett 2005; 392:198-201. [PMID: 16203092 PMCID: PMC3182119 DOI: 10.1016/j.neulet.2005.09.023] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2005] [Revised: 09/01/2005] [Accepted: 09/09/2005] [Indexed: 11/21/2022]
Abstract
Over the last decade neuroscientists have accumulated a wealth of information confirming the trophic effects of 17beta-estradiol (E2) on a variety of brain regions, such as the effects on hippocampal spine density, as well as other measures of structural reorganization. Here, we explore the hypothesis that E2 exerts a positive trophic effect on the cholinergic neurons of the basal forebrain, an area heavily implicated in memory and attentional processes. Female rats were ovariectomized at 3 months of age and lesioned with the immunotoxin 192 IgG-saporin before receiving a subcutaneous pellet containing .25 mg of estrogen or placebo, released over 60 days. The control, non-ovariectomized group was treated identically. At the end of the treatment, the brains were histologically prepared and we used image analysis procedures to evaluate changes in the dendritic arborization of surviving cholinergic neurons. As expected, infusion of the immunotoxin induced a reduction in dendritic arborization in all subjects, but was significantly different from control values only in ovariectomized rats. When differences within animals were factored in, dendritic size in ovariectomized animals treated with E2 was undistinguishable from intact controls. By contrast, in ovariectomized animals treated with placebo, dendritic length remained significantly reduced. These results suggest that E2 can not only protect but also reverse structural neurodegenerative processes in cholinergic neurons. Our data is particularly relevant in the context of female aging and postmenopausal dementia, since preserving an intact cholinergic system may be crucial to prevent at least some of the cognitive decline that occurs in Alzheimer's disease.
Collapse
Affiliation(s)
- Christopher Saenz
- Department of Biology, Pasadena City College, Pasadena, CA 91106, USA
| | - Reymundo Dominguez
- Program in Neuroscience, University of Southern California, Los Angeles, CA 90089, USA
| | - Sonsoles de Lacalle
- Department of Biomedical Sciences, Charles R. Drew University of Medicine and Sciences, 1731 East 120th Street, Los Angeles, CA 90059, USA
- Corresponding author. Tel.: +1 323 563 5853; fax: +1 323 563 5858. (S. de Lacalle)
| |
Collapse
|
30
|
Alvarez-de-la-Rosa M, Silva I, Nilsen J, Pérez MM, García-Segura LM, Avila J, Naftolin F. Estradiol Prevents Neural Tau Hyperphosphorylation Characteristic of Alzheimer's Disease. Ann N Y Acad Sci 2005; 1052:210-24. [PMID: 16024764 DOI: 10.1196/annals.1347.016] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Alzheimer's disease (AD) is three times more prevalent in women than men, and epidemiological studies have shown that estrogen replacement in aging women forestalls the onset of AD. Hyperphosphorylation of the tau protein that forms the neurofibrillary tangles found in AD brains might be responsible for the breakdown of microtubules in affected neurons. The mechanisms by which tau protein is phosphorylated in the AD brain are not fully understood. Using a human neuroblastoma cell line (SH-SY5Y) and primary cultures of newborn male or female rat cerebral cortical neurons, we investigated the effect of 17beta-estradiol on tau protein expression and phosphorylation. We found that estradiol increased total tau and induced dephosphorylation at the proline-directed site of the molecule. Further, estradiol prevented okadaic acid-induced hyperphosphorylation of tau in both proline- and non-proline-directed sites, and antiestrogens blocked this effect. To our knowledge, this is the first report of an effect of estradiol on naturally occurring and induced tau phosphorylation. This assumes special significance because the estrogen action was found to be sexually dimorphic in rat cortical neurons and differentiation-sensitive in human neuroblastoma cells.
Collapse
|
31
|
Abstract
Previous work from our laboratory has shown that in cultures of hypothalamic neurons obtained from male fetuses at embryonic day 16 the axogenic response to estradiol (E2) is contingent upon culture with medium conditioned by astroglia from a target region for hypothalamic axons. E2 also induced increased levels of TrkB that were necessary for the axonal growth to occur. This convergence between estrogenic and neurotrophic signals prompted investigation of the mitogen activated protein kinase (MAPK) cascade. Analysis of the temporal course of MAPK activation showed increased levels of phosphorylated ERK up to 60 min after E2 exposure, with a maximal response at 5-15 min. UO126 (specific inhibitor of MEK 1/2) blocked E2 induced axonal elongation and ERK phosphorylation, confirming the involvement of ERK in the neuritogenic effect of E2. The membrane impermeable construct E2-BSA proved as effective as free E2 to induce axon elongation, suggesting that E2 exerted its effect through a membrane-associated receptor. This possibility received additional support from experiments showing that E2-BSA also increased ERK phosphorylation with the same time course than E2. These results indicate that ERK signaling is necessary for E2 to induce axon growth and this activation is mediated by a membrane bound estrogen receptor.
Collapse
Affiliation(s)
- H F Carrer
- Instituto de Investigación Médica M. y M. Ferreyra, INIMEC-CONICET, Casilla de Correo 389, 5000 Córdoba, Argentina.
| | | | | |
Collapse
|
32
|
Brito VI, Carrer HF, Cambiasso MJ. Inhibition of tyrosine kinase receptor type B synthesis blocks axogenic effect of estradiol on rat hypothalamic neurones in vitro. Eur J Neurosci 2004; 20:331-7. [PMID: 15233742 DOI: 10.1111/j.1460-9568.2004.03485.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
17-beta-estradiol (E2) increases axonal growth and tyrosine kinase receptor (Trk)B levels of male-derived hypothalamic neurones in vitro. To investigate whether the axogenic response depends on the upregulation of TrkB, we analysed neuritic growth and neuronal polarization in cultures treated with an antisense oligonucleotide against TrkB mRNA. In cultures without E2, treatment with 7.5 or 10 micro m antisense reduced TrkB levels and the percentage of neurones showing an identifiable axon; the number and length of minor processes were increased. In cultures treated with 5 micro m antisense, morphometric parameters were normal although total TrkB levels were reduced. The same dose prevented the E2-dependent increase of TrkB levels and suppressed the axogenic effect of E2. These results indicate that TrkB is necessary for normal neuronal growth and maturation and further suggest that an increase in TrkB is necessary for E2 to exert its axogenic effect in male-derived neurones.
Collapse
Affiliation(s)
- V I Brito
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET, Casilla de Correo 389, 5000 Córdoba, Argentina
| | | | | |
Collapse
|
33
|
Nathan BP, Barsukova AG, Shen F, McAsey M, Struble RG. Estrogen facilitates neurite extension via apolipoprotein E in cultured adult mouse cortical neurons. Endocrinology 2004; 145:3065-73. [PMID: 15033916 DOI: 10.1210/en.2003-1707] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Literature review suggests a close relationship between estrogen and apolipoprotein E (ApoE) in the central nervous system. Epidemiology studies show that estrogen replacement therapy (ERT) decreases the morbidity from several chronic neurological diseases. Alleles of ApoE modify the risk for and progression of the same diseases. ApoE levels in the rodent brain vary during the estrous cycle and increase after 17beta-estradiol administration. Both estradiol and ApoE3, the most common isoform of human ApoE, increase the extent of neurite outgrowth in culture. Combined, these observations suggest a common mechanism whereby estrogen may increase ApoE levels to facilitate neurite growth. We tested this hypothesis by characterizing the effects of estradiol and ApoE isoforms on neurite outgrowth in cultured adult mouse cortical neurons. Estradiol increased ApoE levels and neurite outgrowth. ApoE2 increased neurite length more so than ApoE3 in the presence of estradiol. Estradiol had no effect on neurite outgrowth from mice lacking the ApoE gene or when only ApoE4, the isoform of ApoE that is associated with increased risk of neurological disease, was exogenously supplied. Cultures from mice transgenic for human ApoE3 or ApoE4 showed the same isoform-specific effect. Neuronal internalization of recombinant human ApoE3 was greater than ApoE4, and ApoE3 was more effective than ApoE4 in facilitating neuronal uptake of a fatty acid. We conclude that estradiol facilitates neurite growth through an ApoE-dependent mechanism. The effects of ERT on chronic neurological diseases may vary with ApoE genotype. The clinical use of ERT may require ApoE genotyping for optimal efficacy.
Collapse
Affiliation(s)
- Britto P Nathan
- Department of Biological Sciences, Eastern Illinois University, Charleston, Illinois 61920, USA
| | | | | | | | | |
Collapse
|
34
|
Dominguez R, Jalali C, de Lacalle S. Morphological effects of estrogen on cholinergic neurons in vitro involves activation of extracellular signal-regulated kinases. J Neurosci 2004; 24:982-90. [PMID: 14749443 PMCID: PMC3182120 DOI: 10.1523/jneurosci.2586-03.2004] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In the present study, we examined the ability of estrogen to enhance cholinergic neurite arborization in vitro and identified the signal transduction cascade associated with this effect. Basal forebrain primordia collected from rat pups on postnatal day 1 were cultured for 2 weeks and then treated with 5 nm 17beta-estradiol for 24 hr. Cholinergic neurons were identified immunocytochemically with an antibody against the vesicular acetylcholine transporter and digitally photographed. Morphological analysis indicated that female cultures respond to estrogen treatment with an increase in total neurite length per neuron (4.5-fold over untreated controls) and in total branch segment number per neuron (2.3-fold over controls). In contrast, there was no change in total neurite length per neuron in male cultures, and we also observed a decrease in total branch segment number per neuron (0.5-fold below controls). Detailed histograms indicated that estrogen increases primary and secondary branch length and number and also increases terminal neuritic branches to the seventh order in female cultures. In a second set of experiments, we investigated the signal transduction cascade involved in this response, and found that an upstream extracellular signal-regulated kinase (ERK) inhibitor blocked the ability of estrogen to enhance outgrowth in female cultures. Our study provides strong evidence in support of the fact that the ERK pathway is required for estrogen-induced structural plasticity in the cholinergic system of female rats. Understanding the intracellular processes that underlie the response of cholinergic neurons to estrogen provides a necessary step in elucidating how cholinergic neurons can be particularly susceptible to degeneration in postmenopausal women.
Collapse
Affiliation(s)
- Reymundo Dominguez
- Department of Biological Sciences, California State University, Los Angeles, California 90032, USA
| | | | | |
Collapse
|
35
|
Peterson RS, Lee DW, Fernando G, Schlinger BA. Radial glia express aromatase in the injured zebra finch brain. J Comp Neurol 2004; 475:261-9. [PMID: 15211466 DOI: 10.1002/cne.20157] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Estrogens have neurotrophic and neuroprotective properties. The synthesis of estrogen occurs via the expression of aromatase. Previous studies have shown that injury to the vertebrate brain results in a rapid and dramatic up-regulation of aromatase expression in astrocytes around the lesion. As part of experiments examining injury-induced glial aromatization, we identified aromatase in radial glia of the zebra finch brain. Adult female zebra finches received a penetrating injury to the right hippocampus. Twenty-four hours after lesioning, birds were administered bromodeoxyuridine (BrdU) and sacrificed 2 hours, 1 day, or 7 days later. We determined the distribution of aromatase and BrdU labeling by using immunocytochemistry. Radial aromatase was localized to cells lining the lateral ventricle adjacent to the lesioned hippocampus. Injury also induced a dramatic accumulation of newly generated cells labeled with BrdU around the lesion. BrdU labeling was strongly associated with aromatase-positive radial fibers, suggesting the migration of newly generated cells along these fibers. In the songbird brain, estrogen supports neuronal recruitment and promotes the survival and addition of new neurons. The presence of aromatase in radial glia provides a mechanism of estrogen delivery to postmitotic cells. Radial aromatization may be a key feature in the repair of the vertebrate brain following neural injury.
Collapse
Affiliation(s)
- Richard S Peterson
- Department of Physiological Science, University of California, Los Angeles, California 90095, USA.
| | | | | | | |
Collapse
|
36
|
Carrer HF, Cambiasso MJ, Brito V, Gorosito S. Neurotrophic Factors and Estradiol Interact To Control Axogenic Growth in Hypothalamic Neurons. Ann N Y Acad Sci 2003; 1007:306-16. [PMID: 14993063 DOI: 10.1196/annals.1286.029] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Previous work from our laboratory has shown that in cultures of hypothalamic neurons obtained from male fetuses at embryonic day 16, the axogenic response to estrogen (E2) is contingent on coculture with target glia or target glia-conditioned media (CM). Neither the estrogen receptor blockers tamoxifen nor ICI 182,780 prevented the axogenic effects of the hormone. Estradiol made membrane-impermeable by conjugation to a protein of high molecular weight (E2-BSA) preserved its axogenic capacity, suggesting the possibility of a membrane effect responsible for the action of E2. Western blot analysis of extracts from homogenates of cultured neurons grown with E2 and CM from target glia had more TrkB than cultures with CM alone or E2 alone. To further investigate the interaction between E2 and the neurotrophin receptors, we used a specific antisense oligonucleotide (AS) to prevent the estradiol-induced increase of TrkB. The effect of E2 was suppressed in cultures in which TrkB was down-regulated by the AS, showing decreased axonal elongation when compared with neurons treated with E2 without AS or with sense TrkB. In cultures grown with AS, the axonal length of E2-treated cultures was not different from cultures without E2. Evidence suggesting cross-talk between E2 and neurotrophic factor(s) prompted investigation of signaling along the MAPK cascade. Immuno blotting of E2-treated cultures showed increased levels of phosphorylated ERK1 and ERK2. UO126 but not LY294002 blocked E2-induced axonal elongation, suggesting that the MAPKs are involved in this response.
Collapse
Affiliation(s)
- H F Carrer
- Instituto de Investigación Médica M. y M. Ferreyra, INIMEC-CONICET, Casilla de Correo 389, 5000 Cordóba, Argentina.
| | | | | | | |
Collapse
|
37
|
Hayashi K, Kawai-Hirai R, Harada A, Takata K. Inhibitory neurons from fetal rat cerebral cortex exert delayed axon formation and active migration in vitro. J Cell Sci 2003; 116:4419-28. [PMID: 13130100 DOI: 10.1242/jcs.00762] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Inhibitory and excitatory neurons exhibit distinct patterns of development in the mammalian cerebral cortex. The morphological development of inhibitory and excitatory neurons derived from fetal rat cerebral cortex has now been compared in vitro. Inhibitory neurons were identified by immunofluorescence staining with antibodies to gamma-aminobutyric acid, and axon formation was detected by staining with antibodies to phosphorylated neurofilaments. In chemically defined, glia-free and low-density cultures, excitatory neurons formed axons within three days of plating. By contrast, inhibitory neurons required more than six days to form axons. Time-lapse analysis over six days revealed that most inhibitory neurons were bipolar and that their two processes exhibited alternate growth and retraction without giving rise to axons. Movement of the cell body towards the growing process was apparent in about one-half of inhibitory neurons, whereas such movement was never seen in excitatory neurons. The migratory behavior of neurons was further investigated by culture on a glial cell monolayer. Inhibitory neurons migrated over substantially larger distances than did excitatory neurons. The centrosome of inhibitory neurons translocated to the base of the newly emerging leading process, suggesting the existence of a force that pulls intracellular organelles towards the leading process. Centrosome translocation was not detected in excitatory neurons. These observations suggest that the developmental programs of excitatory and inhibitory neurons differ. Inhibitory neurons thus possess a more effective cytoskeletal machinery for migration than excitatory neurons and they form axons later.
Collapse
Affiliation(s)
- Kensuke Hayashi
- Department of Cell Biology, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showamachi, Maebashi, Gunma 371-8512, Japan.
| | | | | | | |
Collapse
|
38
|
Azcoitia I, DonCarlos LL, Garcia-Segura LM. Are gonadal steroid hormones involved in disorders of brain aging? Aging Cell 2003; 2:31-7. [PMID: 12882332 DOI: 10.1046/j.1474-9728.2003.00013.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human aging is associated with a decrease of circulating gonadal steroid hormones. Since these hormones act as trophic factors for neurones and glia, it is possible that the decrease in sex steroid levels may contribute to the increased risk of neurodegenerative disorders with advanced age. Sex steroids are neuroprotective in several animal models of central and peripheral neurodegenerative diseases, and clinical data suggest that these hormones may reduce the risk of neural pathology in aged humans. Potential therapeutic approaches for aged-associated neural disorders may emerge from studies conducted to understand the mechanisms of action of sex steroids in the nervous system of aged animals. Alterations in the endogenous capacity of the aged brain to synthesize and metabolize sex steroids, as well as possible aged-associated modifications in the signalling of sex steroid receptors in the nervous system, are important areas for future investigation.
Collapse
Affiliation(s)
- Iñigo Azcoitia
- Departamento de Biología Celular, Facultad de Biología, Universidad Complutense, E-28040 Madrid, Spain
| | | | | |
Collapse
|
39
|
Ledesma MD, Dotti CG. Membrane and cytoskeleton dynamics during axonal elongation and stabilization. INTERNATIONAL REVIEW OF CYTOLOGY 2003; 227:183-219. [PMID: 14518552 DOI: 10.1016/s0074-7696(03)01010-6] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Proper nervous activities are gradually developing events. Reflecting this, embryonic neurons start differentiation by sprouting multiple extensions, neurites, which do not bear clear axonal or dendritic structural and molecular characteristics. Later in development one of these multiple neurites elongates further, generating a morphologically polarized neuron with a single long axon and many short dendrites. Still, despite such morphological differences these processes can switch destiny, further reflecting their immaturity. Final and irreversible axonal and dendritic commitment occurs after both axons and dendrites have elongated considerably. Recent evidence suggests that the transition from axonal immaturity to maturity reflects changes in the mechanisms used by neurons to control the precise membrane and cytoskeleton polarization. This chapter provides an overview of how these mechanisms contribute to the formation of an axon.
Collapse
Affiliation(s)
- Maria Dolores Ledesma
- Cavalieri Ottolenghi Scientific Institute, Universita degli Studi di Torino, Orbassano, Turin, Italy
| | | |
Collapse
|
40
|
Carrer HF, Cambiasso MJ. Sexual differentiation of the brain: genes, estrogen, and neurotrophic factors. Cell Mol Neurobiol 2002; 22:479-500. [PMID: 12585676 DOI: 10.1023/a:1021825317546] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Based on evidence obtained during the past 50 years, the current hypothesis to explain the sexual dimorphism of structure and function in the brain of vertebrates maintains that these differences are produced by the epigenetic action of gonadal hormones. However, evidence has progressively accumulated suggesting that genetic mechanisms controlling sexual-specific neuronal characteristics precede, or occur in parallel with, hormonal effects. 1. In cultures of hypothalamic neurons taken from gestation day 16 (GD16) embryos, treatment of sexually segregated cultures with estradiol (E2) induces axon growth in neurons from male neurons, but not from female neurons. In these cultures treatment with E2 increased the levels of tyrosine kinase type B (TrkB) and insulin-like growth factor I (IGF-I) receptors in male but not in female neurons. This and other sex differences cannot be explained by differences in hormonal environment, because the donor embryos were obtained when gonadal secretion of steroids is just beginning, before the perinatal surge of testosterone that determines development of the male brain beginning at GD17/18. 2. The response to estrogen is contingent upon coculture with heterotopic glia (mostly astrocytes) from a target region (amygdala) harvested from same-sex fetuses at GD16, whereas in the presence of homotopic glia or in cultures without glia, E2 had no effect. It was concluded that the axogenic effect of E2 depends on interaction between neurons and glia from a target region and that neurons from fetal male donors appear to mature earlier than neurons from females, a differentiated response that takes place prior to divergent exposure to gonadal secretions. 3. The effects of target and nontarget glia-conditioned media (CM) on the E2-induced growth of neuronal processes of hypothalamic neurons obtained from sexually segregated fetal donors were also studied. Estrogen added to media conditioned by target glia modified the number of primary neurites and the growth of axons of hypothalamic neurons of males but not of females. 4. Neither the Type III steroidal receptor blocker tamoxifen nor Type I antiestrogen ICI 182,780 prevented the axogenic effects of the hormone. Estradiol made membrane-impermeable by conjugation to a protein of high molecular weight (E2-BSA) preserved its axogenic capacity, suggesting the possibility of a membrane effect responsible for the action of E2. 5. Western blot analysis of the tyrosine kinase type A (TrkA), type B (TrkB), type C (TrkC), and insulin-like growth factor (IGF-I R) receptors in extracts from homogenates of cultured hypothalamic neurons showed that in cultures of male-derived neurons grown with E2 and CM from target glia, the amounts of TrkB and IGF-I R increased notably. Densitometric quantification showed that these cultures had more TrkB than cultures with CM alone or E2 alone. On the contrary, in cultures of female-derived neurons, the presence of CM alone induced maximal levels of TrkB, which were not further increased by E2; female-derived neurons in all conditions did not contain IGF-I R. Levels of TrkC were not modified by any experimental condition in male- or female-derived cultures and Trk A was not found in the homogenates. These results are compared with similar data from other laboratories and integrated in a model for the confluent interaction of estrogen and neurotrophic factors released by glia that may contribute to the sexual differentiation of the brain.
Collapse
Affiliation(s)
- Hugo F Carrer
- Instituto de Investigación Médica M. y M. Ferreyra, INIMEC-CONICET, Casilla de Correo 389, Córdoba 5000, Argentina.
| | | |
Collapse
|
41
|
Tam J, Danilovich N, Nilsson K, Sairam MR, Maysinger D. Chronic estrogen deficiency leads to molecular aberrations related to neurodegenerative changes in follitropin receptor knockout female mice. Neuroscience 2002; 114:493-506. [PMID: 12204217 DOI: 10.1016/s0306-4522(02)00278-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The follitropin receptor knockout (FORKO) mouse undergoes ovarian failure, thereby providing an animal model to investigate the consequences of the depletion of circulating estrogen in females. The estrogen deficiency causes marked defects in the female reproductive system, obesity, and skeletal abnormalities. In light of estrogen's known pleiotropic effects in the nervous system, our study examined the effects of genetically induced estrogen-testosterone imbalance on this system in female FORKO mice. Circulating concentrations of 17-beta-estradiol (E2) in FORKO mice are significantly decreased (FORKO -/-: 1.13+/-0.34 pg/ml; wild-type +/+: 17.6+/-3.5 pg/ml, P<0.0001, n=32-41); in contrast, testosterone levels are increased (-/-: 37.7+/-2.3 pg/ml; wild-type +/+: 3.9+/-1.7 pg/ml, P<0.005, n=25-33). The focus was on the activities of key enzymes in the central cholinergic and peripheral nervous systems, on dorsal root ganglia (DRGs) capacity for neurite outgrowth, and on the phosphorylation state of structural neurofilament (NF) proteins. Choline acetyltransferase activity was decreased in several central cholinergic structures (striatum 50+/-3%, hippocampus 24+/-2%, cortex 12+/-3%) and in DRGs (11+/-6%). Moreover, we observed aberrations in the enzymatic activities of mitogen-activated protein kinases (extracellular-regulated kinase and c-Jun N-terminal kinase) in the hippocampus, DRGs, and sciatic nerves. Hippocampal and sensory ganglia samples from FORKO mice contained hyper-phosphorylated NFs. Finally, explanted ganglia of FORKO mice displayed decreased neurite outgrowth (20-50%) under non-treated conditions and when treated with E2 (10 nM). Our results demonstrate that genetic depletion of circulating estrogen leads to biochemical and morphological changes in central and peripheral neurons, and underlie the importance of estrogen in the normal development and functioning of the nervous system. In particular, the findings suggest that an early and persisting absence of the steroid leads to neurodegenerative changes and identify several key enzymes that may contribute to the process. This model provides a system to explore the consequences of circulating estrogen deprivation and other hormonal imbalances in the nervous system.
Collapse
Affiliation(s)
- J Tam
- Department of Pharmacology and Therapeutics, McGill University, 3655 Promenade Sir-William-Osler, Room 1314, McIntyre Medical Sciences Building, Montreal, Quebec, Canada H3G 1Y6
| | | | | | | | | |
Collapse
|
42
|
da Silva JS, Dotti CG. Breaking the neuronal sphere: regulation of the actin cytoskeleton in neuritogenesis. Nat Rev Neurosci 2002; 3:694-704. [PMID: 12209118 DOI: 10.1038/nrn918] [Citation(s) in RCA: 348] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The sprouting of neurites, which will later become axons and dendrites, is an important event in early neuronal differentiation. Studies in living neurons indicate that neuritogenesis begins immediately after neuronal commitment, with the activation of membrane receptors by extracellular cues. These receptors activate intracellular cascades that trigger changes in the actin cytoskeleton, which promote the initial breakdown of symmetry. Then, through the regulation of gene transcription, and of microtubule and membrane dynamics, the newly formed neurite becomes stabilized. A key challenge is to define the molecular machinery that regulates the actin cytoskeleton during initial neurite sprouting. We propose that analysing the molecules involved in actin-dependent mechanisms in non-neuronal systems, such as budding yeast and migrating fibroblasts, could help to uncover the secrets of neuritogenesis.
Collapse
Affiliation(s)
- Jorge Santos da Silva
- Cavalieri Ottolenghi Scientific Institute, Universita Degli Studi di Torino, A.O. San Luigi Gonzaga, Regione Gonzole 10, 10024 Orbassano, Torino, Italy
| | | |
Collapse
|
43
|
Zec RF, Trivedi MA. The effects of estrogen replacement therapy on neuropsychological functioning in postmenopausal women with and without dementia: a critical and theoretical review. Neuropsychol Rev 2002; 12:65-109. [PMID: 12371603 DOI: 10.1023/a:1016880127635] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
We review 42 studies examining the effects of estrogen replacement therapy (ERT) on memory and cognition in nondemented postmenopausal women. Although there are an appreciable number of nonsignificant findings, the number of significant findings favoring ERT users considerably outnumbers the rare findings of better performance in controls. Experimental studies demonstrate a consistent beneficial effect on verbal memory, but these are short-term studies of the more acute effects of ERT. The observational studies suggest that there may be a long-lasting effect of continued ERT on cognitive functioning, but these studies need to be interpreted with caution because of the lack of random assignment and a possible "healthy user bias." We also summarize findings from studies on the effects of ERT on Alzheimer's disease (AD). ERT is associated with a decreased risk for dementia, but there is little evidence for a positive effect on cognition in women with AD. Definitive answers to questions about the long-term effects of ERT on cognitive aging and risk of developing AD should be provided by 3 ongoing clinical trials.
Collapse
Affiliation(s)
- Ronald F Zec
- Department of Neurology, Center for Alzheimer Disease and Related Disorders, Southern Illinois University School of Medicine, Springfield 62794-9230, USA.
| | | |
Collapse
|
44
|
Cambiasso MJ, Carrer HF. Nongenomic mechanism mediates estradiol stimulation of axon growth in male rat hypothalamic neurons in vitro. J Neurosci Res 2001; 66:475-81. [PMID: 11746365 DOI: 10.1002/jnr.1238] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The purpose of the present work was to investigate the participation of estradiol receptors (ER) in estrogen-induced axon growth in vitro. Hypothalamic neurons from 16 day (E16) male rat fetuses were cultured with or without 17-beta-estradiol at 1 x 10(-7) M in basal medium or medium conditioned by astroglia derived from ventral mesencephalon (CM). After 48 hr in vitro, neurite outgrowth was quantified by morphometric analysis. An axogenic effect could be demonstrated for estradiol added to CM. With RT-PCR, the mRNA transcript for ERalpha was found in the donor tissues as well as in the neuron cultures. In this model two specific nuclear ER blockers (tamoxifen and ICI 182,780) were ineffective in blocking the neuritogenic effect, and a membrane-impermeable estrogen-albumin construct (E2-BSA) was as effective as estradiol. These results indicate that the axogenic effect of estradiol at E16 is not exerted through the classical intracellular receptor signal transduction system and suggest the possibility of a membrane-mediated mechanism. The data are discussed in light of our previous findings pointing to the interdependent activation of the estrogenic and the trophic factor signaling pathways that mediate stimulated axon growth.
Collapse
Affiliation(s)
- M J Cambiasso
- Instituto de Investigación Médica Mercedes y Martin Ferreyra, INIMEC-CONICET, Córdoba, Argentina
| | | |
Collapse
|
45
|
Gollapudi L, Oblinger MM. Estrogen effects on neurite outgrowth and cytoskeletal gene expression in ERalpha-transfected PC12 cell lines. Exp Neurol 2001; 171:308-16. [PMID: 11573983 DOI: 10.1006/exnr.2001.7744] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The potential of gonadal steroids like estrogen (E) to promote neurite sprouting is of interest in development and aging, as well as after neural trauma. The specific roles of the two main estrogen receptors, ERalpha and ERbeta, in neuronal sprouting are not yet well understood. We examined the hypothesis that E can enhance nerve growth factor (NGF)-stimulated neurite sprouting in an ERalpha-dependent manner. PC12 cells that were stably transfected with the full-length rat ERalpha gene (PCER) and a control line of cells transfected with vector DNA alone (PCCON) were compared. Both cell lines vigorously differentiate neurites when treated with NGF. We determined that both lines show basal expression of ERbeta mRNA, but only the PCER cells express ERalpha mRNA. Estrogen treatment markedly enhanced NGF-stimulated neurite outgrowth from PCER but not from PCCON cells. Significantly larger proportions of PCER cells (34 and 53% at 24 and 48 h, respectively) had neurites than did the PCCON cells (17 and 26% at 24 and 48 h) after E plus NGF treatment. We also examined the effects of E and NGF treatment of PCER and PCCON cells on peripherin, alpha-tubulin, and tau mRNA expression. In undifferentiated PCER cells, E treatment increased peripherin, reduced alpha-tubulin, and did not alter tau mRNA levels. No changes in these mRNAs were observed in the controls (undifferentiated PCCON cells) after E treatment. NGF treatment markedly stimulated expression of peripherin, alpha-tubulin, and tau mRNAs in both PCER and PCCON cells. From these observations we conclude that E synergizes with NGF and stimulates neurite sprouting and also modulates expression of several cytoskeletal mRNAs through ERalpha.
Collapse
Affiliation(s)
- L Gollapudi
- Department of Cell Biology and Anatomy, Chicago Medical School, North Chicago, Illinois 60064, USA
| | | |
Collapse
|
46
|
Peterson RS, Saldanha CJ, Schlinger BA. Rapid upregulation of aromatase mRNA and protein following neural injury in the zebra finch (Taeniopygia guttata). J Neuroendocrinol 2001; 13:317-23. [PMID: 11264718 DOI: 10.1046/j.1365-2826.2001.00647.x] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The expression of aromatase (oestrogen synthase) within the vertebrate central nervous system (CNS) is key in the provision of local oestrogens to neural circuits. Aromatase expression appears to be exclusively neuronal under normal conditions. However, some in vitro studies suggest the presence of astrocytic aromatase in songbirds and mammals. Recently, aromatase in reactive astrocytes has been demonstrated in response to neural injury in the mammalian CNS. Since the glial aromatase expression first documented in cultures of the songbird telencephalon may reflect processes similar to those in response to mammalian neural injury, we investigated whether injury alters the pattern of aromatase-expression in the zebra finch, a species with very high levels of forebrain aromatase expression. Adult males received a penetrating neural injury to the right hemisphere and were killed either 24 or 72 h later. Controls were anaesthetized and otherwise unmanipulated. We determined the expression of aromatase mRNA and protein using in situ hybridization and immunocytochemistry, respectively. Both the transcription and translation of aromatase is dramatically upregulated around the lesion site in response to neural injury in the zebra finch forebrain. This effect is robust and rapid, occurring within 24 h of the injury itself. Cells that upregulate aromatase appear to be reactive astrocytes based upon morphology. The hemisphere contralateral to the injury and both hemispheres in control birds showed the normal, exclusively neuronal pattern of aromatase expression. The upregulation of aromatase in astrocytes may provide high levels of oestrogen available to modulate processes such as CNS repair. Injury-induced upregulation of astrocytic aromatase may be a general characteristic of the injured vertebrate brain.
Collapse
Affiliation(s)
- R S Peterson
- Department of Physiological Science and Laboratory of Neuroendocrinology, Brain Research Institute, University of California Los Angeles, 621 Charles E. Young Drive South, Los Angeles, CA 90095, USA.
| | | | | |
Collapse
|
47
|
Wise PM, Dubal DB, Wilson ME, Rau SW, Liu Y. Estrogens: trophic and protective factors in the adult brain. Front Neuroendocrinol 2001; 22:33-66. [PMID: 11141318 DOI: 10.1006/frne.2000.0207] [Citation(s) in RCA: 179] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Our appreciation that estrogens are important neurotrophic and neuroprotective factors has grown rapidly. Although a thorough understanding of the molecular and cellular mechanisms that underlie this effect requires further investigation, significant progress has been made due to the availability of animal models in which we can test potential candidates. It appears that estradiol can act via mechanisms that require classical intracellular receptors (estrogen receptor alpha or beta) that affect transcription, via mechanisms that include cross-talk between estrogen receptors and second messenger pathways, and/or via mechanisms that may involve membrane receptors or channels. This area of research demands attention since estradiol may be an important therapeutic agent in the maintenance of normal neural function during aging and after injury.
Collapse
Affiliation(s)
- P M Wise
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, Kentucky 40536-0298, USA.
| | | | | | | | | |
Collapse
|
48
|
Abstract
This review highlights recent evidence from clinical and basic science studies supporting a role for estrogen in neuroprotection. Accumulated clinical evidence suggests that estrogen exposure decreases the risk and delays the onset and progression of Alzheimer's disease and schizophrenia, and may also enhance recovery from traumatic neurological injury such as stroke. Recent basic science studies show that not only does exogenous estradiol decrease the response to various forms of insult, but the brain itself upregulates both estrogen synthesis and estrogen receptor expression at sites of injury. Thus, our view of the role of estrogen in neural function must be broadened to include not only its function in neuroendocrine regulation and reproductive behaviors, but also to include a direct protective role in response to degenerative disease or injury. Estrogen may play this protective role through several routes. Key among these are estrogen dependent alterations in cell survival, axonal sprouting, regenerative responses, enhanced synaptic transmission and enhanced neurogenesis. Some of the mechanisms underlying these effects are independent of the classically defined nuclear estrogen receptors and involve unidentified membrane receptors, direct modulation of neurotransmitter receptor function, or the known anti-oxidant activities of estrogen. Other neuroprotective effects of estrogen do depend on the classical nuclear estrogen receptor, through which estrogen alters expression of estrogen responsive genes that play a role in apoptosis, axonal regeneration, or general trophic support. Yet another possibility is that estrogen receptors in the membrane or cytoplasm alter phosphorylation cascades through direct interactions with protein kinases or that estrogen receptor signaling may converge with signaling by other trophic molecules to confer resistance to injury. Although there is clear evidence that estradiol exposure can be deleterious to some neuronal populations, the potential clinical benefits of estrogen treatment for enhancing cognitive function may outweigh the associated central and peripheral risks. Exciting and important avenues for future investigation into the protective effects of estrogen include the optimal ligand and doses that can be used clinically to confer benefit without undue risk, modulation of neurotrophin and neurotrophin receptor expression, interaction of estrogen with regulated cofactors and coactivators that couple estrogen receptors to basal transcriptional machinery, interactions of estrogen with other survival and regeneration promoting factors, potential estrogenic effects on neuronal replenishment, and modulation of phenotypic choices by neural stem cells.
Collapse
|
49
|
Chowen JA, Azcoitia I, Cardona-Gomez GP, Garcia-Segura LM. Sex steroids and the brain: lessons from animal studies. J Pediatr Endocrinol Metab 2000; 13:1045-66. [PMID: 11085182 DOI: 10.1515/jpem.2000.13.8.1045] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Gonadal steroid hormones have multiple effects throughout development on steroid responsive tissues in the brain. The belief that the cellular morphology of the adult brain cannot be modulated or that the synaptic connectivity is "hard-wired" is being rapidly refuted by abundant and growing evidence. Indeed, the brain is capable of undergoing many morphological changes throughout life and gonadal steroids play an important role in many of these processes. Gonadal steroids are implicated in the development of sexually dimorphic structures in the brain, in the control of physiological behaviors and functions and the brain's response to physiological or harmful substances. The effect of sex steroids on neuroprotection and neuroregeneration is an important and expanding area of investigation. Astroglia are targets for estrogen and testosterone and are apparently involved in the actions of sex steroids on the central nervous system. Sex hormones induce changes in the expression of glial fibrillary acidic protein, the growth of astrocytic processes and the extent to which neuronal membranes are covered by astroglial processes. These changes are linked to modifications in the number of synaptic inputs to neurons and suggest that astrocytes may participate in the genesis of gonadal steroid-induced sex differences in synaptic connectivity and synaptic plasticity in the adult brain. Astrocytes and tanycytes may also participate in the cellular effects of sex steroids by releasing neuroactive substances and by regulating the local accumulation of specific growth factors, such as insulin-like growth factor-I, that are involved in estrogen-induced synaptic plasticity and estrogen-mediated neuroendocrine control. Astroglia may also be involved in the regenerative and neuroprotective effects of sex steroids since astroglial activation after brain injury or after peripheral nerve axotomy is regulated by sex hormones.
Collapse
Affiliation(s)
- J A Chowen
- Unit of Investigation, Hospital Niño Jesús, Madrid, Spain.
| | | | | | | |
Collapse
|
50
|
Cambiasso MJ, Colombo JA, Carrer HF. Differential effect of oestradiol and astroglia-conditioned media on the growth of hypothalamic neurons from male and female rat brains. Eur J Neurosci 2000; 12:2291-8. [PMID: 10947808 DOI: 10.1046/j.1460-9568.2000.00120.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
To determine whether soluble products from different CNS regions differ in their ability to support oestrogen-stimulated neurite growth, hypothalamic neurons from sexually segregated embryos were cultured with astroglia-conditioned medium (CM) derived from cortex, striatum and mesencephalon, with or without 17-beta-oestradiol 100 nM added to the medium. After 48 h in vitro, neurite outgrowth was quantified by morphometric analysis. Astroglia-CM from mesencephalon (a target for the axons of hypothalamic neurons) induced the greatest axogenic response in males and in this case only a neuritogenic effect could be demonstrated for oestradiol. On the other hand, astroglia-CM from regions that do not receive projections from ventromedial hypothalamus inhibited axon growth. A sexual difference in the response of hypothalamic neurons to astroglia-CM and oestradiol was found; growth of neurons from female foetuses was increased by astroglia-CM from mesencephalon, but no neuritogenic effect could be demonstrated for oestradiol in these cultures. Blot immunobinding demonstrated the presence of receptors for neurotrophic factors in cultures of hypothalamic neurons; Western blot analysis of these cultures demonstrated that oestradiol increased the concentration of trkB and IGF-I Rbeta, whereas trkA was not detected and the concentration of trkC was not modified. These results support the hypothesis that target regions produce some factor(s) that stimulate the growth of axons from projecting neurons and further indicate that in the case of males this effect is modulated by oestradiol, perhaps mediated through the upregulation of trkB and IGF-I receptors.
Collapse
Affiliation(s)
- M J Cambiasso
- Instituto de Investigación Médica Mercedes y Martin Ferreyra, INIMEC-CONICET, Córdoba, Argentina
| | | | | |
Collapse
|