1
|
Biswas MS, Gelman EM, Alexopoulos DJ, Keen KL, Adam RJ, Terasawa E. The role of neuroestrogens in the estrogen-induced gonadotropin surge in male monkeys. J Neuroendocrinol 2024; 36:e13413. [PMID: 38760983 PMCID: PMC11444899 DOI: 10.1111/jne.13413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 05/02/2024] [Accepted: 05/03/2024] [Indexed: 05/20/2024]
Abstract
Neuroestrogens locally synthesized in the brain are known to play a role in sexual behaviors. However, the question of whether neuroestrogens are involved in the regulation of the gonadotropin-releasing hormone (GnRH) release is just emerging. Because previous studies in this lab indicate that neuroestradiol is also important for the pulsatile release as well as the surge release of GnRH in female rhesus monkeys, in the present study, we examined whether neuroestradiol plays a role in the estrogen-induced LH surge in orchidectomized (ORX) male rhesus monkeys. Unlike in rodents, it is known that a high dose of estrogen treatment can result in the LH surge in ORX male rhesus monkeys. Results that the administration of the aromatase inhibitor, letrozole, failed to attenuate the estrogen-induced LH surge, suggest that unlike in ovariectomized females, neuroestrogens do not play a role in the LH surge experimentally induced by the exogenous estrogen treatment in ORX male monkeys.
Collapse
Affiliation(s)
- Mohammad S. Biswas
- University of Wisconsin-Madison, Wisconsin National Primate Research Center
| | - Erica M. Gelman
- University of Wisconsin-Madison, Wisconsin National Primate Research Center
| | | | - Kim L. Keen
- University of Wisconsin-Madison, Wisconsin National Primate Research Center
| | - Ryan J. Adam
- University of Wisconsin-Madison, Wisconsin National Primate Research Center
| | - Ei Terasawa
- University of Wisconsin-Madison, Wisconsin National Primate Research Center
- Department of Pediatrics, Madison, WI 53715
| |
Collapse
|
2
|
Corre PHC, Mainwaring JM, Peralta KKZ, Lokman PM, Porteous R, Wibowo E. Low dose of propyl-pyrazole-triol, an agonist of estrogen receptor alpha, administration stimulates the Coolidge effect in fadrozole-treated male rats. Horm Behav 2024; 161:105520. [PMID: 38447331 DOI: 10.1016/j.yhbeh.2024.105520] [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: 10/03/2023] [Revised: 02/22/2024] [Accepted: 02/23/2024] [Indexed: 03/08/2024]
Abstract
Estrogen receptor (ER) α is involved in male sexual function. Here, we aim to investigate how ERα activation influences sexual satiety and the Coolidge effect (i.e., when a rat, that has reached sexual satiety, experiences an increased arousal after exposure to a novel sexual partner) in estrogen-deprived male rats. Male rats (8 per group) were treated daily for 29 days with either saline (Control group) or fadrozole dissolved in saline (1 mg/kg/day) 1 h before mating. On Days 13 and 29, rats treated with fadrozole received either no additional treatment (fadrozole group) or a single injection of propyl-pyrazole-triol (ERα-agonist group, dissolved in sesame oil, 1 mg/kg). Rats mated until reaching sexual satiety on Days 13 and 29. In these sessions, the Control group displayed higher frequency of intromission and ejaculation than the other groups. The ERα-agonist group mounted more frequently but reached sexual satiety sooner than the Control group. On Day 29, when exposed to a new sexual partner, the fadrozole-treated rats were less likely to display intromission than the other groups, or ejaculation than the Control group, or mounting than the ERα-agonist group. The Control group showed more ejaculatory behavior and shorter ejaculation latency than the other groups. Body weights, testosterone levels, estradiol levels, and ERα-immunoreactive cell counts in brain regions for sexual behavior were comparable between groups after 29 days of treatments. Our data suggest that estrogen helps regulate sexual satiety and the Coolidge effect in male rats.
Collapse
Affiliation(s)
- P Hanna C Corre
- Department of Anatomy, University of Otago, Dunedin 9016, New Zealand.
| | | | - K Kenn Z Peralta
- Department of Anatomy, University of Otago, Dunedin 9016, New Zealand.
| | - P Mark Lokman
- Department of Zoology, University of Otago, Dunedin 9016, New Zealand.
| | - Robert Porteous
- Otago Micro and Nanoscale Imaging, University of Otago, Dunedin 9016, New Zealand.
| | - Erik Wibowo
- Department of Anatomy, University of Otago, Dunedin 9016, New Zealand.
| |
Collapse
|
3
|
Menéndez-Delmestre R, Agosto-Rivera JL, González-Segarra AJ, Segarra AC. Cocaine sensitization in male rats requires activation of estrogen receptors. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.07.579327. [PMID: 38370714 PMCID: PMC10871307 DOI: 10.1101/2024.02.07.579327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
Gonadal steroids play a modulatory role in cocaine use disorders, and are responsible for many sex differences observed in the behavioral response to cocaine. In females, it is well established that estradiol enhances the behavioral response to cocaine. In males, we have recently shown that testosterone enhances sensitization to cocaine but its mechanism of action remains to be elucidated. The current study investigated the contribution of DHT, a non-aromatizable androgen, and of estradiol, in regulating cocaine-induced sensitization in male rats. Gonadectomized (GDX) male rats treated with estradiol sensitized to repeated cocaine administration, while GDX rats treated with DHT did not, implicating estradiol in cocaine sensitization. Furthermore, intact male rats treated with the antiestrogen ICI 182,780 did not show sensitization to repeated cocaine. This study demonstrates the pivotal role of estradiol in cocaine-induced neuroplasticity and neuroadaptations in the rodent brain.
Collapse
Affiliation(s)
- Raissa Menéndez-Delmestre
- Physiology Department, School of Medicine, University of Puerto Rico, Medical Sciences Campus, PO Box 365067, San Juan, Puerto Rico 00936-5067
| | - José L. Agosto-Rivera
- Department of Biology, University of Puerto Rico, Río Piedras Campus, PO Box 23360, San Juan, Puerto Rico 00931-3360
| | - Amanda J González-Segarra
- Department of Neuroscience and Behavior, Barnard College, Columbia University, New York, New York 10027
| | - Annabell C. Segarra
- Physiology Department, School of Medicine, University of Puerto Rico, Medical Sciences Campus, PO Box 365067, San Juan, Puerto Rico 00936-5067
| |
Collapse
|
4
|
Qiu J, Bosch MA, Zhang C, Rønnekleiv OK, Kelly MJ. Estradiol Protects Neuropeptide Y/Agouti-Related Peptide Neurons against Insulin Resistance in Females. Neuroendocrinology 2019; 110:105-118. [PMID: 31212279 PMCID: PMC6920578 DOI: 10.1159/000501560] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Accepted: 06/17/2019] [Indexed: 12/18/2022]
Abstract
When it comes to obesity, men exhibit a higher incidence of metabolic syndrome than women in early adult life, but this sex advantage wanes in postmenopausal women. A key diagnostic of the metabolic syndrome is insulin resistance in both peripheral tissues and brain, especially in the hypothalamus. Since the anorexigenic hormone 17β-estradiol (E2) regulates food intake in part by inhibiting the excitability of the hypothalamic neuropeptide Y/agouti-related peptide (NPY/AgRP) neurons, we hypothesized that E2 would protect against insulin resistance in NPY/AgRP neurons with diet-induced obesity (DIO). Therefore, we did whole-cell recordings and single cell quantitative polymerase chain reaction in arcuate NPYGFP neurons from both female and male mice to test the efficacy of insulin with DIO. The resting membrane potential and input resistance of NPY/AgRP neurons were significantly increased in DIO versus control-diet fed males. Most notably, the efficacy of insulin to activate KATP channels in NPY/AgRP neurons was significantly attenuated, although the KATP channel opener diazoxide was fully effective in NPY/AgRP neurons from DIO males, indicating that the KATP channels were expressed and functional. In contrast, insulin was fully efficacious to activate KATP channels in DIO females, and the response was reversed by the KATP channel blocker tolbutamide. However, the ability of insulin to activate KATP channels was abrogated with ovariectomy but fully restored with E2 replacement. Insulin resistance in obese males was likely mediated by an increase in suppressor of cytokine signaling-3 (SOCS-3), protein tyrosine phosphatase B (PTP1B) and T-cell protein tyrosine phosphatase (TCPTP) activity, since the expression of all 3 mRNAs were upregulated in the obese males but not in females. As proof of principle, pre-incubation of hypothalamic slices from DIO males with the PTP1B/TCPTP inhibitor CX08005 completely rescued the effects of insulin. Therefore, E2 protects NPY/AgRP neurons in females against insulin resistance through, at least in part, attenuating phosphatase activity. The neuroprotective effects of E2 may explain sex differences in the expression of metabolic syndrome that disappears with the loss of E2 in aging.
Collapse
Affiliation(s)
- Jian Qiu
- Department of Physiology and Pharmacology, Oregon Health
& Science University, Portland, Oregon, USA
| | - Martha A. Bosch
- Department of Physiology and Pharmacology, Oregon Health
& Science University, Portland, Oregon, USA
| | - Chunguang Zhang
- Department of Physiology and Pharmacology, Oregon Health
& Science University, Portland, Oregon, USA
| | - Oline K. Rønnekleiv
- Department of Physiology and Pharmacology, Oregon Health
& Science University, Portland, Oregon, USA
- Division of Neuroscience, National Primate Research Center,
Oregon Health & Science University, Beaverton, Oregon, USA
| | - Martin J. Kelly
- Department of Physiology and Pharmacology, Oregon Health
& Science University, Portland, Oregon, USA
- Division of Neuroscience, National Primate Research Center,
Oregon Health & Science University, Beaverton, Oregon, USA
| |
Collapse
|
5
|
Brocca ME, Garcia-Segura LM. Non-reproductive Functions of Aromatase in the Central Nervous System Under Physiological and Pathological Conditions. Cell Mol Neurobiol 2019; 39:473-481. [PMID: 30084008 DOI: 10.1007/s10571-018-0607-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 07/25/2018] [Indexed: 02/07/2023]
Abstract
The modulation of brain function and behavior by steroid hormones was classically associated with their secretion by peripheral endocrine glands. The discovery that the brain expresses the enzyme aromatase, which produces estradiol from testosterone, expanded this traditional concept. One of the best-studied roles of brain estradiol synthesis is the control of reproductive behavior. In addition, there is increasing evidence that estradiol from neural origin is also involved in a variety of non-reproductive functions. These include the regulation of neurogenesis, neuronal development, synaptic transmission, and plasticity in brain regions not directly related with the control of reproduction. Central aromatase is also involved in the modulation of cognition, mood, and non-reproductive behaviors. Furthermore, under pathological conditions aromatase is upregulated in the central nervous system. This upregulation represents a neuroprotective and likely also a reparative response by increasing local estradiol levels in order to maintain the homeostasis of the neural tissue. In this paper, we review the non-reproductive functions of neural aromatase and neural-derived estradiol under physiological and pathological conditions. We also consider the existence of sex differences in the role of the enzyme in both contexts.
Collapse
Affiliation(s)
- Maria Elvira Brocca
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain.
| | - Luis Miguel Garcia-Segura
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
- Centro de Investigación Biomédica en Red Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
| |
Collapse
|
6
|
Qiu J, Bosch MA, Meza C, Navarro UV, Nestor CC, Wagner EJ, Rønnekleiv OK, Kelly MJ. Estradiol Protects Proopiomelanocortin Neurons Against Insulin Resistance. Endocrinology 2018; 159:647-664. [PMID: 29165691 PMCID: PMC5774249 DOI: 10.1210/en.2017-00793] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 11/01/2017] [Indexed: 12/24/2022]
Abstract
Insulin resistance is at the core of the metabolic syndrome, and men exhibit a higher incidence of metabolic syndrome than women in early adult life, but this sex advantage diminishes sharply when women reach the postmenopausal state. Because 17β-estradiol (E2) augments the excitability of the anorexigenic proopiomelanocortin (POMC) neurons, we investigated the neuroprotective effects of E2 against insulin resistance in POMC neurons from diet-induced obese (DIO) female and male mice. The efficacy of insulin to activate canonical transient receptor potential 5 (TRPC5) channels and depolarize POMC neurons was significantly reduced in DIO male mice but not in DIO female mice. However, the insulin response in POMC neurons was abrogated in ovariectomized DIO females but restored with E2 replacement. E2 increased T-type calcium channel Cav3.1 messenger RNA (mRNA) expression and whole-cell currents but downregulated stromal-interaction molecule 1 mRNA, which rendered POMC neurons more excitable and responsive to insulin-mediated TRPC5 channel activation. Moreover, E2 prevented the increase in suppressor of cytokine signaling-3 mRNA expression with DIO as seen in DIO males. As proof of principle, insulin [intracerebroventricular injection into the third ventricle (ICV)] decreased food intake and increased metabolism in female but not male guinea pigs fed a high-fat diet. The uncoupling of the insulin receptor from its downstream effector system was corroborated by the reduced expression of phosphorylated protein kinase B in the arcuate nucleus of male but not female guinea pigs following insulin. Therefore, E2 protects female POMC neurons from insulin resistance by enhancing POMC neuronal excitability and the coupling of insulin receptor to TRPC5 channel activation.
Collapse
Affiliation(s)
- Jian Qiu
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, Oregon 97239
| | - Martha A. Bosch
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, Oregon 97239
| | - Cecilia Meza
- Department of Basic Medical Sciences, College of Osteopathic Medicine of the Pacific Western University of Health Sciences, Pomona, California 91766
| | - Uyen-Vy Navarro
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, Oregon 97239
| | - Casey C Nestor
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, Oregon 97239
| | - Edward J. Wagner
- Department of Basic Medical Sciences, College of Osteopathic Medicine of the Pacific Western University of Health Sciences, Pomona, California 91766
| | - Oline K. Rønnekleiv
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, Oregon 97239
- Division of Neuroscience, Oregon National Primate Research Center, Beaverton, Oregon 97006
| | - Martin J. Kelly
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, Oregon 97239
- Division of Neuroscience, Oregon National Primate Research Center, Beaverton, Oregon 97006
| |
Collapse
|
7
|
Charif SE, Inserra PIF, Schmidt AR, Di Giorgio NP, Cortasa SA, Gonzalez CR, Lux-Lantos V, Halperin J, Vitullo AD, Dorfman VB. Local production of neurostradiol affects gonadotropin-releasing hormone (GnRH) secretion at mid-gestation in Lagostomus maximus (Rodentia, Caviomorpha). Physiol Rep 2017; 5:5/19/e13439. [PMID: 29038356 PMCID: PMC5641931 DOI: 10.14814/phy2.13439] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 08/17/2017] [Indexed: 01/07/2023] Open
Abstract
Females of the South American plains vizcacha, Lagostomus maximus, show peculiar reproductive features such as massive polyovulation up to 800 oocytes per estrous cycle and an ovulatory process around mid‐gestation arising from the reactivation of the hypothalamic–hypophyseal–ovary (H.H.O.) axis. Estradiol (E2) regulates gonadotropin‐releasing hormone (GnRH) expression. Biosynthesis of estrogens results from the aromatization of androgens by aromatase, which mainly occurs in the gonads, but has also been described in the hypothalamus. The recently described correlation between GnRH and ERα expression patterns in the hypothalamus of the vizcacha during pregnancy, with coexpression in the same neurons of the medial preoptic area, suggests that hypothalamic synthesis of E2 may affect GnRH neurons and contribute with systemic E2 to modulate GnRH delivery during the gestation. To elucidate this hypothesis, hypothalamic expression and the action of aromatase on GnRH release were evaluated in female vizcachas throughout pregnancy. Aromatase and GnRH expression was increased significantly in mid‐pregnant and term‐pregnant vizcachas compared to early‐pregnant and nonpregnant females. In addition, aromatase and GnRH were colocalized in neurons of the medial preoptic area of the hypothalamus throughout gestation. The blockage of the negative feedback of E2 induced by the inhibition of aromatase resulted in a significant increment of GnRH‐secreted mass by hypothalamic explants. E2 produced in the same neurons as GnRH may drive intracellular E2 to higher levels than those obtained from systemic circulation alone. This may trigger for a prompt GnRH availability enabling H.H.O. activity at mid‐gestation with ovulation and formation of accessory corpora lutea with steroidogenic activity that produce the necessary progesterone to maintain gestation to term and guarantee the reproductive success.
Collapse
Affiliation(s)
- Santiago E Charif
- Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y Diagnóstico (CEBBAD), Universidad Maimónides, Ciudad Autónoma de Buenos Aires, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas CONICET, Ciudad Autónoma de Buenos Aires, Argentina
| | - Pablo I F Inserra
- Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y Diagnóstico (CEBBAD), Universidad Maimónides, Ciudad Autónoma de Buenos Aires, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas CONICET, Ciudad Autónoma de Buenos Aires, Argentina
| | - Alejandro R Schmidt
- Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y Diagnóstico (CEBBAD), Universidad Maimónides, Ciudad Autónoma de Buenos Aires, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas CONICET, Ciudad Autónoma de Buenos Aires, Argentina
| | - Noelia P Di Giorgio
- Consejo Nacional de Investigaciones Científicas y Técnicas CONICET, Ciudad Autónoma de Buenos Aires, Argentina.,Laboratorio de Neuroendocrinología, Instituto de Biología y Medicina Experimental, IByME-CONICET, Ciudad Autónoma de Buenos Aires, Argentina
| | - Santiago A Cortasa
- Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y Diagnóstico (CEBBAD), Universidad Maimónides, Ciudad Autónoma de Buenos Aires, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas CONICET, Ciudad Autónoma de Buenos Aires, Argentina
| | - Candela R Gonzalez
- Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y Diagnóstico (CEBBAD), Universidad Maimónides, Ciudad Autónoma de Buenos Aires, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas CONICET, Ciudad Autónoma de Buenos Aires, Argentina
| | - Victoria Lux-Lantos
- Consejo Nacional de Investigaciones Científicas y Técnicas CONICET, Ciudad Autónoma de Buenos Aires, Argentina.,Laboratorio de Neuroendocrinología, Instituto de Biología y Medicina Experimental, IByME-CONICET, Ciudad Autónoma de Buenos Aires, Argentina
| | - Julia Halperin
- Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y Diagnóstico (CEBBAD), Universidad Maimónides, Ciudad Autónoma de Buenos Aires, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas CONICET, Ciudad Autónoma de Buenos Aires, Argentina
| | - Alfredo Daniel Vitullo
- Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y Diagnóstico (CEBBAD), Universidad Maimónides, Ciudad Autónoma de Buenos Aires, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas CONICET, Ciudad Autónoma de Buenos Aires, Argentina
| | - Verónica B Dorfman
- Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y Diagnóstico (CEBBAD), Universidad Maimónides, Ciudad Autónoma de Buenos Aires, Argentina .,Consejo Nacional de Investigaciones Científicas y Técnicas CONICET, Ciudad Autónoma de Buenos Aires, Argentina
| |
Collapse
|
8
|
Sex-Dependent Regulation of Aromatase-Mediated Synaptic Plasticity in the Basolateral Amygdala. J Neurosci 2016; 37:1532-1545. [PMID: 28028198 DOI: 10.1523/jneurosci.1532-16.2016] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 11/11/2016] [Accepted: 12/11/2016] [Indexed: 02/01/2023] Open
Abstract
The basolateral amygdala (BLA) integrates sensory input from cortical and subcortical regions, a function that requires marked synaptic plasticity. Here we provide evidence that cytochrome P450 aromatase (AROM), the enzyme converting testosterone to 17β-estradiol (E2), contributes to the regulation of this plasticity in a sex-specific manner. We show that AROM is expressed in the BLA, particularly in the basolateral nucleus (BL), in male and female rodents. Systemic administration of the AROM inhibitor letrozole reduced spine synapse density in the BL of adult female mice but not in the BL of male mice. Similarly, in organotypic corticoamygdalar slice cultures from immature rats, treatment with letrozole significantly reduced spine synapses in the BL only in cultures derived from females. In addition, letrozole sex-specifically altered synaptic properties in the BL: in acute slices from juvenile (prepubertal) female rats, wash-in of letrozole virtually abolished long-term potentiation (LTP), whereas it did not prevent the generation of LTP in the slices from males. Together, these data indicate that neuron-derived E2 modulates synaptic plasticity in rodent BLA sex-dependently. As protein expression levels of AROM, estrogen and androgen receptors did not differ between males and females and were not sex-specifically altered by letrozole, the findings suggest sex-specific mechanisms of E2 signaling.SIGNIFICANCE STATEMENT The basolateral amygdala (BLA) is a key structure of the fear circuit. This research reveals a sexually dimorphic regulation of synaptic plasticity in the BLA involving neuronal aromatase, which produces the neurosteroid 17β-estradiol (E2). As male and female neurons in rodent BLA responded differently to aromatase inhibition both in vivo and in vitro, our findings suggest that E2 signaling in BLA neurons is regulated sex-dependently, presumably via mechanisms that have been established during sexual determination. These findings could be relevant for the understanding of sex differences in mood disorders and of the side effects of cytochrome P450 aromatase inhibitors, which are frequently used for breast cancer therapy.
Collapse
|
9
|
Cornil CA, Ball GF, Balthazart J. The dual action of estrogen hypothesis. Trends Neurosci 2015; 38:408-16. [PMID: 26089224 DOI: 10.1016/j.tins.2015.05.004] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Revised: 05/18/2015] [Accepted: 05/24/2015] [Indexed: 11/25/2022]
Abstract
Estradiol (E2) can act in the brain in a relatively fast manner (i.e., seconds to minutes) usually through signaling initiated at the cell membrane. Brain-derived E2 has thus been considered as another type of neurotransmitter. Recent work found that behaviors indicative of male sexual motivation are activated by estrogenic metabolites of testosterone (T) in a fast manner, while sexual performance (copulatory behavior per se) is regulated by brain E2 in a slower manner via nucleus-initiated actions. This functional division between these two types of action appears to generalize to other behavioral systems regulated by E2. We propose the dual action of estrogen hypothesis to explain this functional distinction between these two different modes of action.
Collapse
Affiliation(s)
- Charlotte A Cornil
- GIGA Neurosciences, University of Liege, Quartier Hôpital, 15 Avenue Hippocrate, 4000 Liège, Belgium
| | - Gregory F Ball
- Department of Psychology, 2141 Tydings Hall, University of Maryland, College Park, MD 20742-7201, USA
| | - Jacques Balthazart
- GIGA Neurosciences, University of Liege, Quartier Hôpital, 15 Avenue Hippocrate, 4000 Liège, Belgium.
| |
Collapse
|
10
|
Tabatadze N, Sato SM, Woolley CS. Quantitative analysis of long-form aromatase mRNA in the male and female rat brain. PLoS One 2014; 9:e100628. [PMID: 25036039 PMCID: PMC4103800 DOI: 10.1371/journal.pone.0100628] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 05/22/2014] [Indexed: 12/22/2022] Open
Abstract
In vitro studies show that estrogens acutely modulate synaptic function in both sexes. These acute effects may be mediated in vivo by estrogens synthesized within the brain, which could fluctuate more rapidly than circulating estrogens. For this to be the case, brain regions that respond acutely to estrogens should be capable of synthesizing them. To investigate this question, we used quantitative real-time PCR to measure expression of mRNA for the estrogen-synthesizing enzyme, aromatase, in different brain regions of male and female rats. Importantly, because brain aromatase exists in two forms, a long form with aromatase activity and a short form with unknown function, we targeted a sequence found exclusively in long-form aromatase. With this approach, we found highest expression of aromatase mRNA in the amygdala followed closely by the bed nucleus of the stria terminalis (BNST) and preoptic area (POA); we found moderate levels of aromatase mRNA in the dorsal hippocampus and cingulate cortex; and aromatase mRNA was detectable in brainstem and cerebellum, but levels were very low. In the amygdala, gonadal/hormonal status regulated aromatase expression in both sexes; in the BNST and POA, castration of males down-regulated aromatase, whereas there was no effect of estradiol in ovariectomized females. In the dorsal hippocampus and cingulate cortex, there were no differences in aromatase levels between males and females or effects of gonadal/hormonal status. These findings demonstrate that long-form aromatase is expressed in brain regions that respond acutely to estrogens, such as the dorsal hippocampus, and that gonadal/hormonal regulation of aromatase differs among different brain regions.
Collapse
Affiliation(s)
- Nino Tabatadze
- Department of Neurobiology, Northwestern University, Evanston, Illinois, United States of America
- * E-mail:
| | - Satoru M. Sato
- Department of Neurobiology, Northwestern University, Evanston, Illinois, United States of America
| | - Catherine S. Woolley
- Department of Neurobiology, Northwestern University, Evanston, Illinois, United States of America
| |
Collapse
|
11
|
Simerly RB. Prodynorphin and proenkephalin gene expression in the anteroventral periventricular nucleus of the rat: Sexual differentiation and hormonal regulation. Mol Cell Neurosci 2012; 2:473-84. [PMID: 19912832 DOI: 10.1016/1044-7431(91)90014-f] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/1991] [Indexed: 11/16/2022] Open
Abstract
Opioid peptides are generally thought to exert hormone-dependent regulatory influences on gonadotropin secretion and the anteroventral periventricular nucleus (AVPv) has been shown to play a critical role in the neural control of this sexually dimorphic function. In the present study we used in situ hybridization to compare the numbers of proenkephalin (PENK) and prodynorphin (PDYN) mRNA-containing neurons in the AVPv of male and female rats and to evaluate the influence of circulating sex steroid hormones on the development and mature regulation of PENK and PDYN gene expression in these neurons. In agreement with earlier immunohistochemical observations, the number of PENK mRNA-containing neurons in the AVPv of male rats was found to be twice that of female animals. In contrast, the AVPv contains over four times the number of PDYN mRNA-containing cells in female rats, relative to intact males. Treatment of newborn female rats with testosterone increases the number of PENK mRNA-containing neurons in the AVPv, but decreases the number of PDYN mRNA-containing neurons in the AVPv compared with untreated females. Treatment of adult ovariectomized female rats with estradiol significantly increased PDYN mRNA levels in the AVPv; however, comparable changes in levels of PENK mRNA were not detected. In adult male rats, neither PDYN, nor PENK mRNA were significantly altered by orchidectomy or testosterone treatment. Thus, the maintenance of enkephalinergic neurons and the loss of hormone-sensitive dynorphin-containing neurons in the AVPv may represent important developmental influences of neonatal androgens on the sexually differentiated neural circuitry controlling gonadotropin secretion.
Collapse
Affiliation(s)
- R B Simerly
- Division of Neuroscience, Oregon Regional Primate Research Center, Beaverton, Oregon 97006, USA
| |
Collapse
|
12
|
Xu X, Coats JK, Yang CF, Wang A, Ahmed OM, Alvarado M, Izumi T, Shah NM. Modular genetic control of sexually dimorphic behaviors. Cell 2012; 148:596-607. [PMID: 22304924 DOI: 10.1016/j.cell.2011.12.018] [Citation(s) in RCA: 191] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2011] [Revised: 09/22/2011] [Accepted: 12/16/2011] [Indexed: 12/18/2022]
Abstract
Sex hormones such as estrogen and testosterone are essential for sexually dimorphic behaviors in vertebrates. However, the hormone-activated molecular mechanisms that control the development and function of the underlying neural circuits remain poorly defined. We have identified numerous sexually dimorphic gene expression patterns in the adult mouse hypothalamus and amygdala. We find that adult sex hormones regulate these expression patterns in a sex-specific, regionally restricted manner, suggesting that these genes regulate sex typical behaviors. Indeed, we find that mice with targeted disruptions of each of four of these genes (Brs3, Cckar, Irs4, Sytl4) exhibit extremely specific deficits in sex specific behaviors, with single genes controlling the pattern or extent of male sexual behavior, male aggression, maternal behavior, or female sexual behavior. Taken together, our findings demonstrate that various components of sexually dimorphic behaviors are governed by separable genetic programs.
Collapse
Affiliation(s)
- Xiaohong Xu
- Department of Anatomy, University of California, San Francisco, San Francisco, CA 94158, USA
| | | | | | | | | | | | | | | |
Collapse
|
13
|
Hamson DK, Csupity AS, Gaspar JM, Watson NV. Analysis of Foxp2 expression in the cerebellum reveals a possible sex difference. Neuroreport 2009; 20:611-6. [PMID: 19319003 DOI: 10.1097/wnr.0b013e32832a0a44] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Deletion of the gene Foxp2 affects ultrasonic vocalizations and induces morphological abnormalities in the Purkinje cell layer of the cerebellum in mice. Castration decreases the production of ultrasonic vocalizations in rats, but the mechanisms of androgenic regulation of ultrasounds are unknown. We explored a possible relationship between Foxp2 expression and androgens in the Purkinje cell layer of wild-type and androgen-insensitive male rats, as well as estrous and nonestrous female rats. Analyses of relative optical densities of Foxp2 immunoreactivity revealed significantly greater immunolabeling in the wild-type and testicular feminization mutation-affected male rats (which did not differ from each other) than in either the estrous or nonestrous female rats (which similarly did not differ from each other). These data suggest a sex difference in Foxp2 expression in the cerebellum.
Collapse
Affiliation(s)
- Dwayne K Hamson
- Department of Psychology, Simon Fraser University, Burnaby, British Columbia, Canada
| | | | | | | |
Collapse
|
14
|
Zhao C, Fujinaga R, Tanaka M, Yanai A, Nakahama KI, Shinoda K. Region-specific expression and sex-steroidal regulation on aromatase and its mRNA in the male rat brain: immunohistochemical and in situ hybridization analyses. J Comp Neurol 2007; 500:557-73. [PMID: 17120292 DOI: 10.1002/cne.21193] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The brain has an estrogen-biosynthetic potential resulting from the presence of neuronal aromatase, which controls the intraneural sex-steroidal milieu and is involved in brain sexual differentiation, psychobehavioral regulation, and neuroprotection. In the rat brain, three distinct aromatase-P450-immunoreactive (AromP450-I) neural groups have been categorized in terms of their peak expression time (fetal, fetoneonatal, and young-to-adult groups), suggesting the presence of region-specific regulation on brain AromP450. In the present study, we compared the expressions between AromP450 protein and mRNA by using immunohistochemistry and in situ hybridization with an ovary-derived cRNA probe in serial sections of fetal, fetoneonatal, and adult male rat brains and then performed steroidal manipulations to evaluate the sex-steroidal effects on AromP450 in adult orchiectomized and adrenalectomized (OCX + ADX) male rats. As a result, prominent mRNA signals were detected in the fetal (i.e., the anterior medial preoptic nucleus) and fetoneonatal (i.e., the medial preopticoamygdaloid neuronal arc) groups, although no detectable signal was found in the "young-to-adult" group (i.e., the central amygdaloid nucleus). In addition, the "fetoneonatal" AromP450-I neurons were prominently reduced in number and intensity after OCX + ADX and then were reinstated by the administration of dihydrotestosterone, testosterone, or 17beta-estradiol. In contrast, none of the sex steroids had any significant effects on the young-to-adult group. Several possible explanations were explored for why the young-to-adult group may differ in aromatase expression and regulation, including the possibility that distinct splicing variants or isozymes for aromatase exist in the rat brain.
Collapse
Affiliation(s)
- Changjiu Zhao
- Division of Neuroanatomy, Department of Neuroscience, Yamaguchi University School of Medicine, Yamaguchi 755-8505, Japan
| | | | | | | | | | | |
Collapse
|
15
|
Takahashi K, Bergström M, Frändberg P, Vesström EL, Watanabe Y, Långström B. Imaging of aromatase distribution in rat and rhesus monkey brains with [11C]vorozole. Nucl Med Biol 2006; 33:599-605. [PMID: 16843834 DOI: 10.1016/j.nucmedbio.2006.03.009] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2005] [Revised: 03/12/2006] [Accepted: 03/17/2006] [Indexed: 11/22/2022]
Abstract
Aromatase is an enzyme that converts androgens to estrogens and may play a role in mood and mental status. The aim of this study was to demonstrate that brain aromatase distribution could be evaluated with a novel positron emission tomography (PET) tracer [(11)C]vorozole. Vorozole is a nonsteroidal aromatase inhibitor that reversibly binds to the heme domain of aromatase. In vitro experiments in rat brain, using frozen section autoradiography, illustrated specific binding in the medial amygdala (MA), the bed nucleus of stria terminalis (BST) and the preoptic area (POA) of male rat brain. Specific binding in female rat brain was found in the MA and the BST; however, the signals were lower than those of males. The K(d) of [(11)C]vorozole binding to aromatase in MA was determined to be 0.60+/-0.06 nM by Scatchard plot analysis using homogenates. An in vivo PET study in female rhesus monkey brain demonstrated the uptake of [(11)C]vorozole in the amygdala, where the uptake was blocked by the presence of excess amounts of unlabeled vorozole. Thus, this tracer has a high affinity for brain aromatase and could have a potential for in vivo aromatase imaging. This technique might enable the investigation of human brain aromatase in healthy and diseased persons.
Collapse
Affiliation(s)
- Kayo Takahashi
- Division of Pharmacology, Department of Neuroscience, Uppsala University, Uppsala SE-75124, Sweden.
| | | | | | | | | | | |
Collapse
|
16
|
|
17
|
Saldanha CJ, Coomaralingam L. Overlap and co-expression of estrogen synthetic and responsive neurons in the songbird brain--a double-label immunocytochemical study. Gen Comp Endocrinol 2005; 141:66-75. [PMID: 15707604 DOI: 10.1016/j.ygcen.2004.11.013] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2004] [Revised: 11/11/2004] [Accepted: 11/29/2004] [Indexed: 11/16/2022]
Abstract
The songbird telencephalon exhibits the capacity to both synthesize and respond to estrogen. Several telencephalic loci in addition to those in the diencephalon express aromatase (estrogen synthase) and estrogen receptors (ER). Little is known about the interactions between cells that contain aromatase and those that contain ER, particularly at the level of protein expression. Consequently, we do not know if locally synthesized estrogens affect ER via autocrine and/or paracrine mechanisms. Here we have mapped the distributions, identified areas of overlap, and measured the degree of co-expression of aromatase and ERalpha in the zebra finch (Taeniopygia guttata). First, alternate sections were stained with antibodies against either aromatase or ERalpha, revealing the distributions and therefore, the overlap between these proteins. Subsequently, using double-label light microscopy we have measured the number of aromatase soma, ERalpha soma, and co-expressing soma in areas of overlap in adult males and females. In the preoptic area about 10% of aromatase-positive soma co-express ERalpha. In the bed nucleus of the stria terminalis, ventromedial nucleus, nucleus taeniae, and the caudomedial nidopallium, although cells containing either protein were easily detectable, the level of co-expression was minimal. The degree of co-expression and the number of aromatase-positive soma did not differ between sexes. However, the number of ERalpha cells was higher in the female preoptic area relative to that in the male. Conversely, ERalpha is more abundant in the male bed nucleus of the stria terminalis relative to the female. We conclude that while local aromatization in the preoptic area may modulate ERalpha-containing neurons via autocrine pathways, paracrine mechanisms may predominate in other areas of the songbird brain.
Collapse
Affiliation(s)
- Colin J Saldanha
- Department of Biological Sciences, Lehigh University, 111 Research Drive, Bethlehem, PA 18015, USA.
| | | |
Collapse
|
18
|
Fowler CD, Freeman ME, Wang Z. Newly proliferated cells in the adult male amygdala are affected by gonadal steroid hormones. ACTA ACUST UNITED AC 2004; 57:257-69. [PMID: 14608662 DOI: 10.1002/neu.10273] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Gonadal steroid hormones play an important role in the proliferation, survival, and activation of neurons. The present study was performed to examine the effects of testosterone and its metabolites on newly proliferated cells in the amygdala of adult male meadow voles (Microtus pennsylvanicus). Treatment with testosterone propionate (TP) in castrated males resulted in plasma testosterone levels similar to males following mating. TP-treated males displayed a significant increase in the density of cells labeled with a cell proliferation marker (BrdU) in the amygdala. Treatment with estradiol benzoate (EB) exerted a similar effect as TP on the density of BrdU-labeled cells, whereas 5alpha-dihydrotestosterone (DHT) was ineffective. A larger proportion (approximately 44%) of the BrdU-labeled cells in the amygdala displayed a neuronal phenotype, and a lesser percentage (approximately 35%) displayed a glial progenitor phenotype; however, treatment effects were not found in either population of cells. Hormonal effects appeared to be site-specific as no group differences were found in the dentate gyrus of the hippocampus or ventromedial hypothalamus. Finally, a time course study indicated that BrdU-labeled cells in the amygdala are present as early as 30 min following an acute injection of BrdU. Together, these data suggest that gonadal steroid hormones influence the number of newly proliferated cells in the amygdala, most likely by acting through an estrogenic mechanism, and these effects may be exerted on locally proliferating progenitors within the amygdala.
Collapse
Affiliation(s)
- Christie D Fowler
- Department of Psychology, Program in Neuroscience, Florida State University, Tallahassee, Florida 32306, USA.
| | | | | |
Collapse
|
19
|
Gao G, Herbert Z, Kong J, Gabrielson N, Mautz A, Wu D, Jirikowski GF, Caldwell JD. Estradiol control of expression and levels of estradiol-binding proteins in the medial preoptic area, medial hypothalamus and pituitary. Neuroendocrinology 2003; 78:61-71. [PMID: 12915758 DOI: 10.1159/000071961] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2003] [Accepted: 05/05/2003] [Indexed: 11/19/2022]
Abstract
The brains of mammals have at least three estradiol-binding proteins: estradiol receptor-alpha (ERalpha), ERbeta, and sex hormone-binding globulin (SHBG). In this study we compare the effects of estradiol treatment on the expression of mRNA for these three estradiol-binding proteins in two reproductively important brain areas, the medial preoptic area-anterior hypothalamus (MPOA-AH) and medial hypothalamus (MH) as well as in the hippocampus in ovariectomized rats, using the reverse transcriptase-polymerase chain reaction (RT-PCR). We also used surface-enhanced laser desorption ionization time of flight (SELDI-TOF) mass spectrometry (MS) to analyze the effects of estradiol in ovariectomized rats on SHBG levels in the MPOA-MH as well as the neurohypophysis. In vivo estradiol treatment in ovariectomized rats eliminated or significantly reduced expression of all three estradiol-binding proteins in both the MPOA-AH and MH. This change in ERalpha, ERbeta, and SHBG expression did not occur in the hippocampus. Both Northern blot and DNA sequence analysis confirmed the results of the RT-PCR for SHBG. SELDI-TOF MS analysis demonstrated that in vivo estradiol treatments resulted in dramatically decreased levels of SHBG in the hypothalamus and that a reduction in SHBG mRNA by estradiol treatment also resulted in a reduction in SHBG protein levels. Estradiol treatment also eliminated detectable SHBG from the neurohypophysis, suggesting that estradiol controls SHBG levels in this release site. That in vivo estradiol treatments had the same inhibitory effects on mRNA levels for SHBG and both ERs suggests similar translational control mechanisms for all three steroid-binding proteins in the brain. That estradiol treatments also reduced pituitary SHBG suggests that such treatment releases SHBG from the neurohypophysis.
Collapse
Affiliation(s)
- Guang Gao
- Department of Pharmaceutical Sciences, North Dakota State University, Fargo, North Dakota, USA
| | | | | | | | | | | | | | | |
Collapse
|
20
|
Lephart ED, Call SB, Rhees RW, Jacobson NA, Weber KS, Bledsoe J, Teuscher C. Neuroendocrine regulation of sexually dimorphic brain structure and associated sexual behavior in male rats is genetically controlled. Biol Reprod 2001; 64:571-8. [PMID: 11159360 DOI: 10.1095/biolreprod64.2.571] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Steroid hormones, particularly 17beta-estradiol (E2), regulate the development and expression of neural structures and sexual behavior. Recently, we demonstrated that E2-regulated responses are controlled by quantitative trait loci. In this study, we quantified 1) volume of the sexually dimorphic nucleus (SDN) of the preoptic area (POA); 2) medial basal hypothalamic (MBH)-POA aromatase and 5alpha-reductase enzyme activities during prenatal development and in adults; 3) serum LH, testosterone, FSH, E2, prolactin (PRL), and corticosterone levels; 4) reproductive organ (i.e., testis and ventral prostate) weights; and 5) male mating behavior in Noble (NB/Cr) and Wistar-Furth (WF/NCr) rat strains to determine the genetic influence on the measured parameters. Maximal phenotypic divergence in male SDN-POA volumes was seen between NB/Cr versus WF/NCr and BDIX/Cr rats (among nine rat strains initially examined), with the average SDN-POA volume of NB/Cr male rats being significantly greater ( approximately 30%) than that of either WF/NCr or BDIX/Cr males. Subsequent experiments investigated WF/NCr versus NB/Cr male rats in further detail. Significantly higher MBH-POA aromatase activity was seen in adult WF/NCr versus NB/Cr males, while MBH-POA 5alpha-reductase rates were not significantly different (within or between sex) for the two rat strains assayed. Serum LH levels were significantly higher (by greater than sixfold) in WF/NCr versus NB/Cr males, whereas testis organ:body weight and ventral prostate:body weight ratios in WF/NCr versus NB/Cr males were significantly smaller (by approximately 6-fold for testis and approximately 1.5-fold for prostate values). Serum FSH levels were significantly higher (by twofold) in WF/NCr versus NB/Cr males. However, serum testosterone levels were not significantly different, whereas E2 levels were approximately twofold higher (but not significantly different) in WF/NCr versus NB/Cr animals. No significant differences were found in basal (i.e., nonstress) serum PRL or corticosterone levels between the WF/NCr and NB/Cr males. In male copulatory tests, NB/Cr males exhibited significantly more aggressive sexual behavior (e.g., in mounting, intromission, and ejaculation parameters) compared with WF/NCr males. Taken together, these findings indicate that WF/NCr males are, in general, low responders, whereas NB/Cr males are high responders to hormonal signals. The obtained data suggest that the correlative, phenotypic variation in SDN-POA volume (i.e., structure) and reproductive hormone patterns and mating behavior (i.e., function) of WF/NCr versus NB/Cr males is regulated by potentially E2-mediated mechanisms that are genetically controlled.
Collapse
Affiliation(s)
- E D Lephart
- Neuroscience Center, 633 WIDB, Brigham Young University, Provo, UT 84602, USA.
| | | | | | | | | | | | | |
Collapse
|
21
|
Guerriero G, Roselli CE, Paolucci M, Botte V, Ciarcia G. Estrogen receptors and aromatase activity in the hypothalamus of the female frog, Rana esculenta. Fluctuations throughout the reproductive cycle. Brain Res 2000; 880:92-101. [PMID: 11032993 DOI: 10.1016/s0006-8993(00)02798-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
It is well known that certain actions of androgen are mediated through in situ aromatization to estrogen in neural target tissues. This study was undertaken to investigate androgen utilization in the hypothalamus of the female frog, Rana esculenta, through a quantification of estrogen receptors and aromatase activity during the reproductive cycle. 3H-estradiol-binding molecules were present in both the cytosol and the nuclear extract of the hypothalamus. These molecules bound specifically 3H-estradiol with high affinity (Kd 10(-10) M) and low capacity (cytosol: 1.2+/-0.4 fmol/mg protein; nuclear extract: 7.9+/-0.6 fmol/mg protein). Aromatase activity was detected in the microsomal fraction of the hypothalamus using a sensitive in vitro radiometric assay. Both aromatase activity and nuclear estrogen receptor binding fluctuated in synchrony throughout the reproductive cycle. Western blot analysis of aromatase protein revealed one immunoreactive band with a molecular weight of approximately 56 kDa. In contrast to aromatase enzyme activity, the relative levels of aromatase protein changed little during the reproductive cycle suggesting that post-translational mechanisms may be involved in regulating estrogen synthesis in the frog brain. A possible role for estrogens in the modulation of the reproductive behavior in this species is suggested.
Collapse
Affiliation(s)
- G Guerriero
- Department of Zoology, Federico II University, Via Mezzocannone, 8, 80134, Naples, Italy.
| | | | | | | | | |
Collapse
|
22
|
Pinckard KL, Stellflug J, Resko JA, Roselli CE, Stormshak F. Review: brain aromatization and other factors affecting male reproductive behavior with emphasis on the sexual orientation of rams. Domest Anim Endocrinol 2000; 18:83-96. [PMID: 10701766 DOI: 10.1016/s0739-7240(99)00065-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- K L Pinckard
- Department of Animal Sciences, Oregon State University, Corvallis 97331-6702, USA
| | | | | | | | | |
Collapse
|
23
|
Segovia S, Guillamón A, del Cerro MC, Ortega E, Pérez-Laso C, Rodriguez-Zafra M, Beyer C. The development of brain sex differences: a multisignaling process. Behav Brain Res 1999; 105:69-80. [PMID: 10553691 DOI: 10.1016/s0166-4328(99)00083-2] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
In order to account for the development of sex differences in the brain, we took, as an integrative model, the vomeronasal pathway, which is involved in the control of reproductive physiology and behavior. The fact that brain sex differences take place in complex neural networks will help to develop a motivational theory of sex differences in reproductive behaviors. We also address the classic genomic actions in which three agents (the hormone, the intracellular receptor, and the transcription function) play an important role in brain differentiation, but we also point out refinements that such a theory requires if we want to account of the existence of two morphological patterns of sex differences in the brain, one in which males show greater morphological measures (neuron numbers and/or volume) than females and the opposite. Moreover, we also consider very important processes closely related to neuronal afferent input and membrane excitability for the developing of sex differences. Neurotransmission associated to metabotropic and ionotropic receptors, neurotrophic factors, neuroactive steroids that alter membrane excitability, cross-talk (and/or by-pass) phenomena, and second messenger pathways appear to be involved in the development of brain sex differences. The sexual differentiation of the brain and reproductive behavior is regarded as a cellular multisignaling process.
Collapse
Affiliation(s)
- S Segovia
- Departamento de Psicobiología, Universidad Nacional de Educación a Distancia, Madrid, Spain.
| | | | | | | | | | | | | |
Collapse
|
24
|
Lephart ED, Butler PC, Mills RH, Jacobson NA, Ladle DR, Bloch GJ. Effects of testosterone and progesterone on brain 5alpha-reductase and aromatase in Long-Evans males and comparison of aromatase in Long-Evans vs. Sprague-Dawley rats. Brain Res 1998; 789:327-30. [PMID: 9573394 DOI: 10.1016/s0006-8993(97)01553-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We investigated medial basal hypothalamic-preoptic area (MBH-POA) 5alpha-reductase and aromatase enzyme activities in gonadally intact and castrated adult Long-Evans (L-E) male rats treated with testosterone (T), progesterone (P), and a combination of T+P. MBH-POA 5alpha-reductase and aromatase activities did not differ significantly among the groups. The lack of a difference in MBH-POA aromatase between control and castrated L-E animals was unexpected. In two further experiments, MBH-POA aromatase was examined in intact and castrated L-E and Sprague-Dawley (S-D) rats, using direct and indirect assays. The activity in castrated S-D (but again, not in L-E) rats significantly decreased compared to control values. These data suggest that the absence of gonads does not decrease MBH-POA aromatase in adult L-E rats.
Collapse
Affiliation(s)
- E D Lephart
- Department of Psychology, Brigham Young University, Provo, UT 84602, USA. edwin@lephart@.byu.edu
| | | | | | | | | | | |
Collapse
|
25
|
Abstract
In the early eighties we found sex differences in the vomeronasal organ (VNO) and hypothesized that the vomeronasal system (VNS), a complex neural network involved in the control of reproductive behavior, might be sexually dimorphic. At that time sex differences had already been described for some structures that receive VNO input, such as the medial amygdala, the medial preoptic area, the ventromedial hypothalamic nucleus, and the ventral region of the premammillary nucleus. Since then, we have shown sex differences in the accessory olfactory bulb (AOB), the bed nucleus of the accessory olfactory tract (BAOT), and the bed nucleus of the stria terminalis (BST). When new VNS connections were found, all of them ended in nuclei that present sex differences. In general, sex differences in the olfactory system show two morphological patterns: one in which males present greater morphological measures than females, and just the opposite. To explain the morphometric measures of males in the latter, it has been hypothesized that androgens serve as inhibitors. Our work on the involvement of the GABA(A) receptor in the development of AOB and maternal behavior sex differences also suggests that neonatal changes in neuronal membrane permeability to the ion Cl- differences. This might be the first animal model to help us to understand the situation in which human genetic and gonadal sex do not agree with brain and behavioral sex. Finally, we stress that sex differences in the VNS constitute a neurofunctional model for understanding sex differences in reproductive behaviors.
Collapse
Affiliation(s)
- A Guillamón
- Departamento de Psicobiología, Universidad Nacional de Educación a Distancia, Ciudad Universitaria, Madrid, Spain
| | | |
Collapse
|
26
|
Zwain IH, Yen SS, Cheng CY. Astrocytes cultured in vitro produce estradiol-17beta and express aromatase cytochrome P-450 (P-450 AROM) mRNA. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1334:338-48. [PMID: 9101730 DOI: 10.1016/s0304-4165(96)00115-8] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Aromatase cytochrome P-450 (P-450AROM) is an enzyme that catalyzes the conversion of androgen to estrogen. Estrogen plays an important role in the neuronal function by promoting the formation of dendrites and may be involved in protecting the neurons in the cerebral cortex against specific pathological conditions such as Alzheimer's disease. However, the cellular origin of estrogen in the brain is not known. The present study demonstrated for the first time the production of estradiol-17beta and expression of P-450AROM mRNA in astrocytes isolated from the cerebral cortex of neonatal rats. Immunocytochemical studies using a monospecific antibody against rat P-450AROM has shown that this enzyme was localized in the cytoplasm of astrocytes. Interleukin-1 (IL-1) has been shown to stimulate the proliferation and differentiation of astrocytes and to affect the aromatase activity in non-neuronal cells such as Sertoli, Leydig, and placental cells. Treatment of astrocytes with IL-1beta induced a dose-dependent inhibition of estradiol production. This inhibitory action of IL-1beta can be reversed by the addition of anti-IL-1beta antibody. Since astrocytes are involved in the synaptic reorganization in the brain by removing cellular debris and by providing the necessary biological factors for neuronal growth, the ability of astrocytes to produce estradiol-17beta and express P-450AROM mRNA in vitro suggests a new role for these cells in protecting and supporting neurons.
Collapse
Affiliation(s)
- I H Zwain
- The Population Council, Center for Biomedical Research, New York, NY 10021, USA
| | | | | |
Collapse
|
27
|
Iqbal J, Swanson JJ, Prins GS, Jacobson CD. Androgen receptor-like immunoreactivity in the Brazilian opossum brain and pituitary: distribution and effects of castration and testosterone replacement in the adult male. Brain Res 1995; 703:1-18. [PMID: 8719610 DOI: 10.1016/0006-8993(95)00983-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Androgens are involved in a variety of centrally mediated functions after binding to their intracellular receptors. In the present report, we have employed the androgen receptor antibody, PG-21, and indirect immunohistochemistry to examine the distribution of cells containing androgen receptor-like immunoreactivity (AR-IR) in the intact adult male Brazilian opossum brain and pituitary. Additional adult males were castrated to examine the effects of withdrawal of circulating androgens and testosterone replacement on AR-IR. Immunoblots and immunohistochemical controls demonstrated that the androgen receptor in the opossum brain and peripheral tissues are of a similar molecular mass as to has been reported for the rat. Cells containing AR-IR were widely distributed throughout the brain of intact adult males. The highest number of immunoreactive cells were present in the dorsal and ventral nuclei of the lateral septum, medial division of the bed nucleus of the stria terminalis, medial preoptic area, median preoptic nucleus, nucleus of the lateral olfactory tubercle, central amygdaloid nucleus, anterior cortical amygdaloid nucleus, posterior amygdaloid nucleus, subiculum, ventromedial hypothalamic nucleus, arcuate-median eminence region, and ventral premammillary nucleus. The anterior pituitary gland also contained a high number of cells containing AR-IR. The general distribution of AR-IR both in the brain and anterior pituitary gland resembled that reported for other mammalian species. Castration of the adult males four days prior to perfusion eliminated androgen receptor immunostaining throughout the brain except for a few lightly immunostained cells in the ventral nucleus of the lateral septum and stria terminalis. Androgen receptor immunostaining was decreased in the anterior pituitary gland following castration and became cytoplasmic. Testosterone administration 2 h before perfusion restored AR-IR both in the brain and anterior pituitary gland. These data suggested that immunohistochemical detection of bound (nuclear) androgen receptors as seen with PG-21 antibody in the brain and anterior pituitary gland of the opossum is dependent upon circulating androgens. Further, the wide distribution and similarity in localization of androgen receptors in the opossum brain and anterior pituitary gland to that of other species suggests that androgen receptors might be involved in similar functions in the opossum as has been reported for other species.
Collapse
Affiliation(s)
- J Iqbal
- Department of Veterinary Anatomy and Neuroscience Program, Iowa State University, Ames, 50011, USA
| | | | | | | |
Collapse
|
28
|
Kawata M. Roles of steroid hormones and their receptors in structural organization in the nervous system. Neurosci Res 1995; 24:1-46. [PMID: 8848287 DOI: 10.1016/0168-0102(96)81278-8] [Citation(s) in RCA: 258] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Due to their chemical properties, steroid hormones cross the blood-brain barrier where they have profound effects on neuronal development and reorganization both in invertebrates and vertebrates, including humans mediated through their receptors. Steroids play a crucial role in the organizational actions of cellular differentiation representing sexual dimorphism and apoptosis, and in the activational effects of phenotypic changes in association with structural plasticity. Their sites of action are primarily the genes themselves but some are coupled with membrane-bound receptor/ion channels. The effects of steroid hormones on gene transcription are not direct, and other cellular components interfere with their receptors through cross-talk and convergence of the signaling pathways in neurons. These genomic and non-genomic actions account for the divergent effects of steroid hormones on brain function as well as on their structure. This review looks again at and updates the tremendous advances made in recent decades on the study of the role of steroid (gonadal and adrenal) hormones and their receptors on developmental processes and plastic changes in the nervous system.
Collapse
Affiliation(s)
- M Kawata
- Department of Anatomy and Neurobiology, Kyoto Prefectural University of Medicine, Japan
| |
Collapse
|
29
|
Yamada-Mouri N, Hirata S, Hayashi M, Kato J. Analysis of the expression and the first exon of aromatase mRNA in monkey brain. J Steroid Biochem Mol Biol 1995; 55:17-23. [PMID: 7577717 DOI: 10.1016/0960-0760(95)00157-u] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
To elucidate the mechanism of the region-specific expression of the aromatase in the primate brain, we investigated the distribution and level of the total aromatase mRNA and the aromatase mRNA with the exon 1-f, which was reported to be the brain-specific exon 1 of the human aromatase gene, in male Japanese monkeys. Total RNAs extracted from the hypothalamus-preoptic area (HPOA), amygdala (AMY), cerebellum, hippocampus, brainstem, five regions of cerebral cortex and four peripheral tissues: liver, kidney, adipose tissue and testis were subjected to a semi-quantitative reverse transcription-polymerase chain reaction-Southern blotting (RT-PCR-SB) assay. The levels of the total aromatase mRNA was high in the HPOA, AMY and testis with a low level of message in the other regions. These results roughly paralleled the distribution of aromatase activity of the monkey brain previously reported. The level of the aromatase mRNA with the exon 1-f was high in the HPOA and AMY, and low in the other regions of the brain and the testis with an undetectable level of the messenger in the other peripheral tissues. Furthermore, the ratio of the aromatase mRNA with the exon 1-f to the total aromatase mRNA was different among various regions of the monkey brain, for example, the ratio in the AMY was distinctly higher than that in the HPOA. These results indicated that the level of the aromatase mRNA mainly regulated the level of aromatase protein and aromatase activity in a region-specific manner, and that the exon 1-f was used in most of the monkey brain regions. Moreover, the ratio of the aromatase mRNA with the exon 1-f to the total aromatase mRNA varied in the brain regions. It was implied that the aromatase mRNA using the other first exons was also expressed in the brain and was involved in the region-specific expression of the brain aromatase.
Collapse
Affiliation(s)
- N Yamada-Mouri
- Department of Obstetrics and Gynecology, Yamanashi Medical University, Japan
| | | | | | | |
Collapse
|
30
|
Abstract
The conversion of testosterone to estradiol is catalyzed by cytochrome P450 aromatase. In situ aromatization is required for the full expression of the effects of testosterone in the brain. This study examined the subcellular distribution and reaction kinetics of aromatase in the adult rat brain. Preoptic area, hypothalamus and amygdala were homogenized in isotonic sucrose buffered with potassium phosphate. Tissue homogenates were fractionated by ultracentrifugation. Aromatase activity was measured using a previously validated 3H2O assay. Marker enzymes were measured to identify organelles in the different subcellular fractions. Aromatase activity in all 3 tissues was enriched 10-fold in microsomes, but not in other subcellular fractions. The addition of either a NADPH-generating system or 1 mM NADPH to the reaction mixture stimulated aromatase activity in all subcellular fractions, whereas NADH was only minimally effective. In general, substrate affinity constants were equivalent in all brain areas and subcellular fractions (approximately 10 nM) suggesting that one predominant catalytic form of the enzyme is present in the rat brain. One week after castration, aromatase activity was significantly reduced in all subcellular fractions of preoptic area and in the whole homogenate and microsomal fraction of the hypothalamus. Castration did not significantly alter aromatase activity in any subcellular compartment of amygdala. To more critically evaluate its subcellular localization, aromatase activity was measured in purified synaptosomes. Aromatase activity was not enriched in these preparations suggesting that it is not substantially associated with nerve terminals in rat brain.
Collapse
Affiliation(s)
- C E Roselli
- Department of Physiology, Oregon Health Sciences University, Portland 97201-3098, USA
| |
Collapse
|
31
|
Shinoda K, Nagano M, Osawa Y. Neuronal aromatase expression in preoptic, strial, and amygdaloid regions during late prenatal and early postnatal development in the rat. J Comp Neurol 1994; 343:113-29. [PMID: 8027430 DOI: 10.1002/cne.903430109] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Brain aromatase has been considered to be an important clue in elucidating the actions of androgen on brain sexual differentiation. Using highly specific anti-P450arom antiserum, the regional and subcellular distributions were immunohistochemically evaluated in the preoptic, strial, and amygdaloid regions of developing rat brains. Aromatase-immunoreactive (AROM-I) neurons were classified into three groups. The first, in which immunostaining occurs only during certain pre- or neonatal days (E16-P2), included the anterior medial preoptic nucleus, the periventricular preoptic nucleus, neurons associated with the strial part of the preoptic area, and the rostral portion of the medial preoptic nucleus. The second is a striking AROM-I cell group in the "medial preopticoamygdaloid neuronal arc," which extends from the medial preoptic nucleus to the principal nucleus of the bed nucleus of the stria terminalis and the posterodorsal part of the medial amygdaloid nucleus. The AROM-I neurons appeared by E16, reaching a peak in staining intensity between E18 and P2 and diminishing after the perinatal stage. After P14, a third group of AROM-I neurons emerged in the lateral septal nucleus, the oval nucleus of the bed nucleus of the stria terminalis, and the central amygdaloid nucleus. The second group was thought to be the major aromatization center in developing rat brains, while the center might partly shift to the third group of neurons after the late infantile stage. The distribution and developmental patterns were basically similar in males and females, suggesting that the neonatally prominent aromatase is not induced by male-specific androgen surges occurring around birth. On immunoelectron microscopy, subneuronal aromatase was predominantly localized on the nuclear membrane and endoplasmic reticulum, which appeared to be appropriate for the efficient conversion of androgen into estrogen just prior to binding to the nuclear receptors.
Collapse
Affiliation(s)
- K Shinoda
- Department of Anatomy II, Kinki University School of Medicine, Osaka, Japan
| | | | | |
Collapse
|
32
|
Nagano M, Shinoda K. Coexistence of the stigmoid body and estrogen receptor in some neuronal groups involved in rat reproductive functions. Brain Res 1994; 634:296-304. [PMID: 8131080 DOI: 10.1016/0006-8993(94)91933-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Recent immunohistochemical studies have suggested that the forebrain distribution of stigmoid bodies, marked by an antibody against placental aromatase-associated antigen X-P2 (PAX), overlaps with that of the common binding sites of androgen and estrogen. In the present light- and electron-microscopy study the coexistence of stigmoid bodies and estrogen receptors (EsR) is immunohistochemically examined and quantitatively analyzed in the medial preoptic region, part of the bed nucleus of the stria terminalis and part of the medial amygdaloid nucleus of young female rats. Light microscopy with double immunostaining for PAX and EsR in all three regions indicates that 75-84% of the total of PAX-immunoreactive stigmoid structures are present in neurons which also contain EsR-immunoreactive nuclei, and that 75-78% of EsR-immunoreactive neurons contain PAX-immunoreactive inclusions. Electron microscopic analysis confirms that 70-80% of stigmoid body-containing neurons have EsR-immunoreactive nuclei. These results indicate that the majority of the stigmoid bodies and EsRs intimately coexist, strongly suggesting a functional interrelationship in brain regions which are involved in rat reproductive functions. Stigmoid bodies may play a role in subneuronal EsR mechanisms associated with aromatization in these sex steroid targets in rat brain.
Collapse
Affiliation(s)
- M Nagano
- Department of Anatomy II, Kinki University School of Medicine, Osaka, Japan
| | | |
Collapse
|
33
|
Demotes-Mainard J, Vernier P, Vincent JD. Hormonal control of neural function in the adult brain. Curr Opin Neurobiol 1993; 3:989-96. [PMID: 8124084 DOI: 10.1016/0959-4388(93)90172-u] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Although the mechanisms by which peripheral hormones modulate complex behaviors are far from being well understood, recent advances in deciphering the mechanisms of hormone action in the brain are promising. Current areas of interest include the molecular mechanisms of steroid receptor action, the steroid modulation of synaptic function, and the mediation of steroid-regulated neuronal and glial plasticity by growth factors or proteins associated with brain development.
Collapse
|
34
|
Lisciotto CA, Morrell JI. Circulating gonadal steroid hormones regulate estrogen receptor mRNA in the male rat forebrain. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1993; 20:79-90. [PMID: 8255184 DOI: 10.1016/0169-328x(93)90112-3] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
In male rats, the conversion of testosterone to estrogen via aromatization is a critical step in a number of androgen-mediated functions, especially reproductive behavior. Within the central nervous system (CNS), locally formed estrogen binds to its cognate estrogen receptor protein. Little is known about what factors regulate the expression of estrogen receptors in the male rat CNS. This study examined whether circulating male gonadal steroid hormones have a role in the regulation of estrogen receptor mRNA in brain regions critical for the expression of male reproductive behavior. Male rats were gonadectomized or sham operated, and 3 days later were sacrificed. Their brains were fixed by perfusion, frozen, and sectioned. Tissue sections were hybridized to an 35S-labeled 850 base cDNA probe, complementary primarily to the steroid binding domain of the estrogen receptor mRNA. Following post-hybridization washes, slides were dipped in photographic emulsion and exposed for 2 weeks. Estrogen receptor mRNA-containing neurons were observed in all brain regions previously shown by steroid hormone autoradiography to concentrate estrogen. Gonadectomy did not alter the number of estrogen receptor mRNA-producing neurons, but did produce a two-fold increase in the relative amount of estrogen receptor mRNA per cell in the medial preoptic nucleus, periventricular preoptic area, and bed nucleus of the stria terminalis. This study shows that circulating gonadal steroids down-regulate steady state levels of estrogen receptor mRNA within specific brain regions, and thereby have the potential to regulate the sensitivity of particular target regions in the CNS to estrogen.
Collapse
Affiliation(s)
- C A Lisciotto
- Institute of Animal Behavior, Rutgers, State University of New Jersey, Newark 07102
| | | |
Collapse
|
35
|
Jakab RL, Horvath TL, Leranth C, Harada N, Naftolin F. Aromatase immunoreactivity in the rat brain: gonadectomy-sensitive hypothalamic neurons and an unresponsive "limbic ring" of the lateral septum-bed nucleus-amygdala complex. J Steroid Biochem Mol Biol 1993; 44:481-98. [PMID: 8476763 DOI: 10.1016/0960-0760(93)90253-s] [Citation(s) in RCA: 114] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The aromatase (estrogen synthetase) enzyme catalyzes the conversion of androgens to estrogens in peripheral tissues, as well as in the brain. Our study aimed at comparing the brain distribution of aromatase-immunoreactive neurons in male and female, normal and gonadectomized rats. Light microscopic immunostaining was employed using a purified polyclonal antiserum raised against human placental aromatase. Two anatomically separate aromatase-immunoreactive neuronal systems were detected in the rat brain: A "limbic telencephalic" aromatase system was composed by a large population of labeled neurons in the lateral septal area, and by a continuous "ring" of neurons of the laterodorsal division of the bed nucleus of stria terminalis, central amygdaloid nucleus, stria terminalis, and the substantia inominata-ventral pallidum-fundus striati region. The other, "hypothalamic" aromatase system consisted of neurons scattered in a dorsolateral hypothalamic area including the paraventricular, lateral and dorsomedial hypothalamic nuclei, the subincertal nucleus as well as the zona incerta. In addition, a few axon-like processes (unresponsive to gonadectomy) were present in the preoptic-anterior hypothalamic complex, the ventral striatum, and midline thalamic regions. No sexual dimorphism was observed in the distribution or intensity of aromatase-immunostaining. However, 3 days, 2, 3, 8, 16, or 32 weeks after gonadectomy, aromatase-immunoreactive neurons disappeared from the hypothalamus, whereas they were still present in the limbic areas of both sexes. The results indicate the existence of two distinct estrogen-producing neuron systems in the rat brain: (1) a "limbic ring" of aromatase-labeled neurons of the lateral septum-bed nucleus-amygdala complex unresponsive to gonadectomy; and (2) a sex hormone-sensitive "hypothalamic" aromatase neuron system.
Collapse
Affiliation(s)
- R L Jakab
- Department of Obstetrics and Gynecology, Yale University, School of Medicine, New Haven, CT 06510
| | | | | | | | | |
Collapse
|
36
|
Shinoda K, Nagano M, Osawa Y. An aromatase-associated cytoplasmic inclusion, the "stigmoid body," in the rat brain: II. Ultrastructure (with a review of its history and nomenclature). J Comp Neurol 1993; 329:1-19. [PMID: 8384220 DOI: 10.1002/cne.903290102] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The ultrastructure of aromatase-associated "stigmoid (dot-like) structures," which were detected in a previous study using light-microscopic immunohistochemistry (Shinoda et al.: J. Comp. Neurol. 322:360-376, '92), were examined in the rat medial preoptic region, bed nucleus of the stria terminalis, medial amygdaloid nucleus, and arcuate nucleus by pre- and post-embedding marking with a polyclonal antibody against human placental antigen X-P2 (hPAX-P2) for immuno-electron microscopic analysis. The immunoreactive stigmoid structure was identified as a distinct, non-membrane-bounded cytoplasmic inclusion (approximately 1-3 microns in diameter), which has a granulo-fuzzy texture with moderate-to-low electron density in non-immunostained preparations. It consists of at least four distinct granular and three distinct fibrillo-tubular elements forming a granulo-fibrillar conglomerate. This type of inclusions was formally termed the "stigmoid body" under the electron microscope. The stigmoid body is composed of the outer granulo-fibrillar and inner hyaloplasmic compartments. The immunoreactivity for hPAX-P2 is mainly localized to the former, especially to the low density granulo-fuzzy materials associated with the fibrillo-tubular elements. Identification of the ultrastructure of stigmoid body clarified their prevalence not only in the limbic and hypothalamic regions, but also in sex-steroid-sensitive peripheral tissues (e.g., peripheral sensory ganglia, ovary, testis) by consulting earlier electron-microscopic studies. Reviewing the history and nomenclature of this inclusion body, we reorganized the terminology of related neuronal cytoplasmic inclusions, the terms of which have often been confused, and discussed its functional significance on the basis of the present and previously accumulated data. In conclusion, we emphasized the importance of the stigmoid bodies in the sex-steroid-sensitive neural system because of their large size, high frequency, specific distribution in brains and peripheral tissues, effects of sex-steroids, and immunological and histochemical characteristics of the antibody marking the inclusion. The stigmoid bodies may provide a subcellular site for sex-steroid metabolism in their target tissues and play a critical role in cytosolic modulation of their actions (e.g., by aromatization) prior to their receptor binding.
Collapse
Affiliation(s)
- K Shinoda
- Department of Anatomy II, Kinki University School of Medicine, Osaka, Japan
| | | | | |
Collapse
|
37
|
Segovia S, Guillamón A. Sexual dimorphism in the vomeronasal pathway and sex differences in reproductive behaviors. BRAIN RESEARCH. BRAIN RESEARCH REVIEWS 1993; 18:51-74. [PMID: 8467350 DOI: 10.1016/0165-0173(93)90007-m] [Citation(s) in RCA: 194] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Several years ago we hypothesized that the vomeronasal system (VNS), a complex neural network involved in the control of reproductive behavior, might be sexually dimorphic. This hypothesis sprung from several facts; (a) the existence of steroid receptors in the VNS; (b) sexual dimorphism was already described in some structures that receive vomeronasal input, such as the medial preoptic area, the ventromedial hypothalamic nucleus, the ventral region of the premammillary nucleus and the medial amygdaloid nucleus; and (c) the vomeronasal organ, which is the receptor organ of the VNS, was also sexually dimorphic. After that point, the accessory olfactory bulb (AOB), the bed nucleus of the accessory olfactory tract (BAOT) and the bed nucleus of the stria terminalis were found to be sexually dimorphic. The aim of the present review is to show the experimental facts that confirm our earlier hypothesis and, consequently, to present the existence of a sexually dimorphic multisynaptic pathway for the first time in mammals. Sexual dimorphism in the VNS might provide a comprehensive approach to understanding the neural bases of sexually dimorphic reproductive behavior and it is suggested here that the greater number of neurons which male rats present in relation to females in most VNS structures might contribute to the inhibition of the expression of feminine copulatory behavior (lordosis) and maternal behavior in males. In addition, the mechanisms that control the development of sexual dimorphism in the VNS are discussed. The discussion takes into account the two patterns of sexual dimorphism found in the rat brain. Estrogens seem to promote the development of sexual dimorphism in both male and female rats. However, an inhibitory role of androgens might be necessary to hypothesize when males or females present a lower number of neurons and/or volume than the opposite sex. There are experimental data supporting this hypothesis in the female, since dihydrotestosterone seems to facilitate neuronal death in VNS structures, such as the AOB and the BAOT, in which females present a lower number of neurons and volume than male rats. Finally, since the lateral division of the bed nucleus of the stria terminalis, which belongs to the main olfactory system (MOS), is sexually dimorphic and presents anatomical relationships with some VNS structures the MOS might be sexually dimorphic.
Collapse
Affiliation(s)
- S Segovia
- Departamento de Psicobiología, Universidad Nacional de Educación a Distancia, Madrid, Spain
| | | |
Collapse
|
38
|
Negri Cesi P, Melcangi RC, Celotti F, Martini L. Aromatase activity in cultured brain cells: difference between neurons and glia. Brain Res 1992; 589:327-32. [PMID: 1393598 DOI: 10.1016/0006-8993(92)91294-o] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
At the level of the central nervous system (CNS) of several mammalian and non-mammalian species, estrogens may be intracellularly formed from circulating androgens through the action of the aromatase complex. Estrogenic steroids play a crucial role in organizing and directing certain behavioral and neuroendocrine responses both during the fetal/neonatal life and in adulthood. Biochemical and immunocytochemical studies have shown that the aromatase is particularly concentrated in CNS areas involved in the control of reproductive functions, such as the hypothalamus, the preoptic area and the limbic system; despite this large body of evidence, the exact cellular localization of this enzymatic complex within the different cell populations of the brain is still uncertain. In the experiments described here, the presence of the aromatase has been evaluated in the two main cellular components of the brain: the neurons and the glia. In these experiments, cultures of neurons obtained from the brains of 14-15-day-old rat embryos, mixed glial cells from 1-day-old rats and type 1 astrocytes derived from cultured glial cells, have been utilized. The aromatase has been also evaluated in oligodendrocytes isolated from adult male rat brain by density gradient ultracentrifugation. The aromatase activity has been assayed by an 'in vitro' radiometric method which quantifies the production of tritiated water from [1 beta-3H]-androstenedione as an index of estrogen formation. The validity of the method has been verified both on the placental microsomes and on rat hypothalamic tissue, in which the actual formation of estrogens has also been measured.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- P Negri Cesi
- Department of Endocrinology, University of Milan, Italy
| | | | | | | |
Collapse
|
39
|
Shinoda K, Mori S, Ohtsuki T, Osawa Y. An aromatase-associated cytoplasmic inclusion, the "stigmoid body," in the rat brain: I. Distribution in the forebrain. J Comp Neurol 1992; 322:360-76. [PMID: 1325485 DOI: 10.1002/cne.903220306] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
An aromatase-containing neural system was examined in the rat forebrain, using a polyclonal antibody against aromatase-associated human placental antigen X-P2 (hPAX-P2). Numerous dot-like structures, which we have called stigmoid bodies, were immunostained in the preoptico-hypothalamic region, the bed nucleus of the stria terminalis, the medial amygdala, the arcuate nucleus, the subfornical organ, and the area extending from the hypothalamic area to the central gray through the medial forebrain bundle and the periventricular fiber system of the posterior diencephalon. The stigmoid bodies were always found as inclusions in the neuronal cytoplasm. Their diameter was usually 1-3 microns, but exceptionally large forms, over 3 microns, were found in some brain regions, including the area extending from the median preoptic nucleus surrounding the organosum vasculosum laminae terminalis to the anterior medial preoptic nucleus, the periventricular nucleus of the preoptic area, and some parts of the medial preoptic nucleus. Most of these nuclei show sexual dimorphism. The distribution pattern of the hPAX-P2 immunoreactive stigmoid bodies agreed well with that of aromatase activity previously reported in many biochemical studies. Brain regions where the stigmoid bodies were prominent largely coincide with steroid binding locations common to both androgen and estrogen, or regions where both sex steroid receptors are present. Although it still remains to be determined whether aromatase is localized within these stigmoid bodies, it appears likely that they are closely associated with the function of sex steroids at their target sites in the brain.
Collapse
Affiliation(s)
- K Shinoda
- Department of Anatomy II, Kinki University School of Medicine, Osaka, Japan
| | | | | | | |
Collapse
|
40
|
Connolly PB, Roselli CE, Resko JA. Androgen-dependent and -independent aromatase activity coexists with androgen receptors in male Guinea-pig brain. J Neuroendocrinol 1991; 3:679-84. [PMID: 19215538 DOI: 10.1111/j.1365-2826.1991.tb00333.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Abstract Using a microdissection technique we localized androgen receptors and aromatase activity (AA) in the brain of male guinea-pigs. In addition, we evaluated the effects of castration and androgen replacement on androgen receptor dynamics and induction of AA. In the castrate animal, cytosolic androgen receptor content was highest in the basal hypothalamus, specifically in the median eminence-arcuate nucleus (> 15 fmol mg protein (1)), while lesser levels were found in the preoptic regions and amygdala. Nuclear receptor content was highest (> 150 fmol mg DNA (-1)) in the median eminence-arcuate nucleus, periventricular region of the preoptic area and cortical amygdala. All regions investigated showed a significant decrease in nuclear receptors following castration and an increase with androgen replacement. However, reciprocal changes in cytosolic androgen receptors were not always evident. Aromatase activity was high in the cortical amygdala, medial amygdala, periventricular region of the preoptic area and bed nucleus of the stria terminalis. Castration and androgen replacement had significant stimulatory effects on AA in the ventral medial hypothalamus, median eminence-arcuate nucleus, cortical amygdala and periventricular regions of the preoptic area and anterior hypothalamus. Thus, androgen receptors and AA are unevenly distributed throughout the subcortical regions of the male guinea-pig brain and respond differently to endocrine stimuli. Our data demonstrate that AA is androgen-dependent in some subcortical regions which contain androgen receptors. Even though nuclear receptors in all brain regions were affected by castration and dihydrotestosterone treatment, the events were not always linked to AA regulation. Due to this difference in regulation, AA may serve divergent functions in guinea-pig brain.
Collapse
Affiliation(s)
- P B Connolly
- Department of Physiology, School of Medicine, Oregon Health Sciences University, Portland, Oregon 97201, USA
| | | | | |
Collapse
|
41
|
Simerly RB, Chang C, Muramatsu M, Swanson LW. Distribution of androgen and estrogen receptor mRNA-containing cells in the rat brain: an in situ hybridization study. J Comp Neurol 1990; 294:76-95. [PMID: 2324335 DOI: 10.1002/cne.902940107] [Citation(s) in RCA: 1588] [Impact Index Per Article: 46.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The distribution of cells that express mRNA encoding the androgen (AR) and estrogen (ER) receptors was examined in adult male and female rats by using in situ hybridization. Specific labeling appeared to be largely, if not entirely, localized to neurons. AR and ER mRNA-containing neurons were widely distributed in the rat brain, with the greatest densities of cells in the hypothalamus, and in regions of the telencephalon that provide strong inputs in the medial preoptic and ventromedial nuclei, each of which is thought to play a key role in mediating the hormonal control of copulatory behavior, as well as in the lateral septal nucleus, the medial and cortical nuclei of the amygdala, the amygdalohippocampal area, and the bed nucleus of the stria terminalis. Heavily labeled ER mRNA-containing cells were found in regions known to be involved in the neural control of gonadotropin release, such as the anteroventral periventricular and the arcuate nuclei, but only a moderate density of labeling for AR mRNA was found over these nuclei. In addition, clearly labeled cells were found in regions with widespread connections throughout the brain, including the lateral hypothalamus, intralaminar thalamic nuclei, and deep layers of the cerebral cortex, suggesting that AR and ER may modulate a wide variety of neural functions. Each part of Ammon's horn contained AR mRNA-containing cells, as did both parts of the subiculum, but ER mRNA appeared to be less abundant in the hippocampal formation. Moreover, AR and ER mRNA-containing cells were also found in olfactory regions of the cortex and in both the main and accessory olfactory bulbs. AR and ER may modulate nonolfactory sensory information as well since labeled cells were found in regions involved in the central relay of somatosensory information, including the mesencephalic nucleus of the trigeminal nerve, the ventral thalamic nuclear group, and the dorsal horn of the spinal cord. Furthermore, heavily labeled AR mRNA-containing cells were found in the vestibular nuclei, the cochlear nuclei, the medial geniculate nucleus, and the nucleus of the lateral lemniscus, which suggests that androgens may alter the central relay of vestibular and auditory information as well. However, of all the regions involved in sensory processing, the heaviest labeling for AR and ER mRNA was found in areas that relay visceral sensory information such as the nucleus of the solitary tract, the area postrema, and the subfornical organ. We did not detect ER mRNA in brainstem somatic motoneurons, but clearly labeled AR mRNA-containing cells were found in motor nuclei associated with the fifth, seventh, tenth, and twelfth cranial nerves. Similarly, spinal motoneurons contained AR but not ER mRNA.(ABSTRACT TRUNCATED AT 400 WORDS)
Collapse
Affiliation(s)
- R B Simerly
- Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, California 92037
| | | | | | | |
Collapse
|
42
|
Simerly RB. Hormonal control of neuropeptide gene expression in sexually dimorphic olfactory pathways. Trends Neurosci 1990; 13:104-10. [PMID: 1691870 DOI: 10.1016/0166-2236(90)90186-e] [Citation(s) in RCA: 89] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
An abundance of experimental literature has established that gonadal steroid hormones are responsible for the sexual differentiation of neural circuitry, mediating a variety of reproductive behaviors and physiological mechanisms. These same hormones regulate the expression of reproductive function in the adult and may influence the responsiveness of the brain to specific olfactory cues. The recent demonstration that the expression of the neuropeptide cholecystokinin is activationally regulated by estrogen at the mRNA level, within a sexually dimorphic population of neurons in the medial amygdala, suggests a possible cellular mechanism for the hormonal modulation of olfactory information relayed along the vomeronasal pathway to the hypothalamus.
Collapse
Affiliation(s)
- R B Simerly
- Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, CA 92037
| |
Collapse
|