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Carrillo B, Fernandez-Garcia JM, García-Úbeda R, Grassi D, Primo U, Blanco N, Ballesta A, Arevalo MA, Collado P, Pinos H. Neonatal inhibition of androgen activity alters the programming of body weight and orexinergic peptides differentially in male and female rats. Brain Res Bull 2024; 208:110898. [PMID: 38360152 DOI: 10.1016/j.brainresbull.2024.110898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 02/02/2024] [Accepted: 02/07/2024] [Indexed: 02/17/2024]
Abstract
The involvement of androgens in the regulation of energy metabolism has been demonstrated. The main objective of the present research was to study the involvement of androgens in both the programming of energy metabolism and the regulatory peptides associated with feeding. For this purpose, androgen receptors and the main metabolic pathways of testosterone were inhibited during the first five days of postnatal life in male and female Wistar rats. Pups received a daily s.c. injection from the day of birth, postnatal day (P) 1, to P5 of Flutamide (a competitive inhibitor of androgen receptors), Letrozole (an aromatase inhibitor), Finasteride (a 5-alpha-reductase inhibitor) or vehicle. Body weight, food intake and fat pads were measured. Moreover, hypothalamic Agouti-related peptide (AgRP), neuropeptide Y (NPY), orexin, and proopiomelanocortin (POMC) were analyzed by quantitative real-time polymerase chain reaction assay. The inhibition of androgenic activity during the first five days of life produced a significant decrease in body weight in females at P90 but did not affect this parameter in males. Moreover, the inhibition of aromatase decreased hypothalamic AgRP mRNA levels in males while the inhibition of 5α-reductase decreased hypothalamic AgRP and orexin mRNA levels in female rats. Finally, food intake and visceral fat, but not subcutaneous fat, were affected in both males and females depending on which testosterone metabolic pathway was inhibited. Our results highlight the differential involvement of androgens in the programming of energy metabolism as well as the AgRP and orexin systems during development in male and female rats.
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Affiliation(s)
- Beatriz Carrillo
- Department of Psychobiology, National University of Distance Education, Madrid, Spain; University Institute of Research-UNED-Institute of Health Carlos III (IMIENS), Madrid, Spain
| | - Jose Manuel Fernandez-Garcia
- University Institute of Research-UNED-Institute of Health Carlos III (IMIENS), Madrid, Spain; Faculty of Psychology, Universidad Villanueva Madrid, Madrid, Spain
| | - Rocío García-Úbeda
- Department of Psychobiology, National University of Distance Education, Madrid, Spain
| | - Daniela Grassi
- Department of Anatomy, Histology and Neuroscience, Autonomous University of Madrid, Madrid, Spain
| | - Ulises Primo
- Department of Psychobiology, National University of Distance Education, Madrid, Spain
| | - Noemí Blanco
- Department of Psychobiology, National University of Distance Education, Madrid, Spain; University Institute of Research-UNED-Institute of Health Carlos III (IMIENS), Madrid, Spain
| | - Antonio Ballesta
- Department of Psychobiology, Centro de Enseñanza Superior Cardenal Cisneros, Spain
| | - Maria Angeles Arevalo
- Neuroactive Steroids Lab, Cajal Institute, CSIC, Madrid, Spain; Centro de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
| | - Paloma Collado
- Department of Psychobiology, National University of Distance Education, Madrid, Spain; University Institute of Research-UNED-Institute of Health Carlos III (IMIENS), Madrid, Spain
| | - Helena Pinos
- Department of Psychobiology, National University of Distance Education, Madrid, Spain; University Institute of Research-UNED-Institute of Health Carlos III (IMIENS), Madrid, Spain.
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2
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Regional distribution of 5α-reductase type 2 in the adult rat brain: an immunohistochemical analysis. Psychoneuroendocrinology 2013; 38:281-93. [PMID: 22776423 PMCID: PMC3762250 DOI: 10.1016/j.psyneuen.2012.06.008] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 06/18/2012] [Accepted: 06/18/2012] [Indexed: 11/20/2022]
Abstract
The enzyme 5α-reductase (5αR) catalyzes the conversion of testosterone and other Δ(4)-3-ketosteroids into their 5α-reduced metabolites. Of the five members of the 5αR family, the type 2 enzyme (5αR2) plays a key role in androgen metabolism, and is abundantly distributed in the urogenital system. Although 5αR2 has been reported to be highly expressed in the brain during early developmental stages, little is currently known on its anatomical and cellular distribution in the adult brain. Thus, the present study was designed to determine the detailed localization of 5αR2 in the adult rat brain, using a highly specific polyclonal antibody against this isoform. Parasagittal and coronal sections revealed 5αR2 immunoreactivity throughout most brain regions, with strong immunolabeling in the layers III and VI of the prefrontal and somatosensory cortex, olfactory bulb, thalamic nuclei, CA3 field of hippocampus, basolateral amygdala and Purkinje cell layer of cerebellum. Lower 5αR2 levels were detected in the hypothalamus and midbrain. Moreover, double labeling fluorescence with confocal laser scanning microscopy (CLSM) revealed that 5αR2 is localized in neurons, but not in glial cells. Specifically, the enzyme was documented in the pyramidal neurons of the cortex by CLSM analysis of simultaneous Golgi-Cox and immunofluorescent staining. Finally, low levels of 5αR2 expression were identified in GABAergic cells across the cortex, hippocampus and striatum. These findings show that, in the adult brain, 5αR2 is distributed in critical regions for behavioral regulation, suggesting that the functional role of this isoform is present throughout the entire lifespan of the individual.
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3
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Sánchez P, Torres JM, Castro B, Del Moral RG, de Dios Luna J, Ortega E. Steroid 5α-reductase in adult rat brain after neonatal dihydrotestosterone administration. Neurochem Res 2012; 38:557-63. [PMID: 23229791 DOI: 10.1007/s11064-012-0948-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 10/22/2012] [Accepted: 12/01/2012] [Indexed: 11/29/2022]
Abstract
Testosterone (T) is known to play an important masculinizing role in the developing brain of rat, including the regulation of 5α-reductase (5α-R) isozymes. However, the effects of dihydrotesterone (DHT), a more potent androgen than T, have not been elucidated. In this study, DHT was administered from day 5 through day 20 of postnatal life (period of postnatal sexual differentiation of the central nervous system) at doses of: 12 mg/kg/d on days 5, 6, 7, 8, 19, and 20; 15 mg/kg/d on days 9, 10, 11, 12, 16, 17, and 18; and 18 mg/kg/d on days 13, 14, and 15. In adulthood, quantitative RT-PCR was used to measure mRNA levels of 5α-R1 and 5α-R2 isozymes in the prefrontal cortex (PFC) of male and female rats with varied androgenic status. Under our study conditions, neonatal DHT administration influenced on adult PFC 5α-R isozymes levels and their regulation pattern by androgens, and this pattern was the inverse of that reported in adult neonatally T-treated rats.
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Affiliation(s)
- P Sánchez
- Department of Biochemistry and Molecular Biology, School of Medicine, University of Granada, Avda. de Madrid s/n, 18012, Granada, Spain
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4
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Sánchez P, Torres JM, del Moral RG, de Dios Luna J, Ortega E. Steroid 5α-reductase in adult rat brain after neonatal testosterone administration. IUBMB Life 2011; 64:81-6. [DOI: 10.1002/iub.569] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Accepted: 08/04/2011] [Indexed: 11/12/2022]
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5
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Oboti L, Peretto P, Marchis SD, Fasolo A. From chemical neuroanatomy to an understanding of the olfactory system. Eur J Histochem 2011; 55:e35. [PMID: 22297441 PMCID: PMC3284237 DOI: 10.4081/ejh.2011.e35] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Accepted: 09/20/2011] [Indexed: 02/04/2023] Open
Abstract
The olfactory system is the appropriate model for studying several aspects of neuronal physiology spanning from the developmental stage to neural network remodelling in the adult brain. Both the morphological and physiological understanding of this system were strongly supported by classical histochemistry. It is emblematic the case of the Olfactory Marker Protein (OMP) staining, the first, powerful marker for fully differentiated olfactory receptor neurons and a key tool to investigate the dynamic relations between peripheral sensory epithelia and central relay regions given its presence within olfactory fibers reaching the olfactory bulb (OB). Similarly, the use of thymidine analogues was able to show neurogenesis in an adult mammalian brain far before modern virus labelling and lipophilic tracers based methods. Nowadays, a wealth of new histochemical techniques combining cell and molecular biology approaches is available, giving stance to move from the analysis of the chemically identified circuitries to functional research. The study of adult neurogenesis is indeed one of the best explanatory examples of this statement. After defining the cell types involved and the basic physiology of this phenomenon in the OB plasticity, we can now analyze the role of neurogenesis in well testable behaviours related to socio-chemical communication in rodents.
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Affiliation(s)
- L Oboti
- Department of Animal and Human Biology, University of Turin, Italy
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6
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Sánchez P, Torres JM, Ortega E. Effects of dihydrotestosterone on brain mRNA levels of steroid 5alpha-reductase isozymes in early postnatal life of rat. Neurochem Res 2005; 30:577-81. [PMID: 16076027 DOI: 10.1007/s11064-005-2692-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
We studied the expression of type 1 (5alpha-R1) and type 2 (5alpha-R2) 5alpha-reductase isozymes (5alpha-R) and their regulation by dihydrotestosterone (DHT) in the prefrontal cortex of male and female rats during postnatal sexual differentiation of the central nervous system (CNS), using one-step quantitative RT-PCR coupled with laser-induced fluorescence capillary electrophoresis. We found a higher expression of 5alpha-R2, which is considered a masculinizing enzyme, in the female versus male CNS, and observed sexual dimorphism in the regulation of both 5alpha-R isozymes by DHT. These results open up a new research line that could improve understanding of the role of 5alpha-R isozymes in the physiology of the CNS.
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Affiliation(s)
- Pilar Sánchez
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Granada, Avda. de Madrid s/n, Granada, Spain
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7
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Tai FD, Wang TZ, Zhang YH, Sun RY. Sexual dimorphism of the vomeronasal organ and the accessory olfactory bulb of the mandarin voleMicrotus mandarinus and the reed voleM. fortis. ACTA ACUST UNITED AC 2004. [DOI: 10.1007/bf03192506] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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8
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Galanopoulou AS, Moshé SL. Role of sex hormones in the sexually dimorphic expression of KCC2 in rat substantia nigra. Exp Neurol 2003; 184:1003-9. [PMID: 14769394 DOI: 10.1016/s0014-4886(03)00387-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2003] [Revised: 07/17/2003] [Accepted: 07/22/2003] [Indexed: 10/26/2022]
Abstract
KCC2 is a neuronal-specific potassium chloride cotransporter. The level of KCC2 expression is a factor determining whether GABA(A) receptor agonists depolarize or hyperpolarize neurons. Substantia nigra reticulata (SNR) neurons of male postnatal day 15 (PN15) rats have low KCC2 mRNA expression and respond to GABA(A) receptor activation with depolarization and activation of calcium-regulated gene expression. Female PN15 SNR neurons have high KCC2 mRNA expression and GABA(A) receptor agonists cannot activate calcium-dependent signaling processes. We investigate whether sex hormones regulate KCC2 mRNA expression in PN15 rat SNR. Using in situ hybridization, we studied the effects of acute (4 h) or prolonged (52 h) subcutaneous (s.c.) administration of testosterone (100 microg), dihydrotestosterone (180 microg) or 17beta-estradiol benzoate (5 microg) on KCC2 mRNA expression in male and female PN15 rat SNR. Different doses of estradiol (1 and 10 microg s.c., 4 h) were also acutely administered in female PN15 rats. Controls received oil injections. Separate groups of PN15 male rats were pretreated with antagonists of L-type voltage-sensitive calcium channels (L-VSCCs) [nifedipine, 100 mg/kg s.c.] or GABA(A) receptors [bicuculline, 2 mg/kg intraperitoneally (i.p.)] or their vehicles, 30 min before estradiol (5 microg s.c., 4 h). Testosterone and dihydrotestosterone upregulated KCC2 mRNA in both sexes. Estradiol downregulated KCC2 mRNA in males but not in females. Both acute and prolonged hormonal administration had similar effects. In male PN15 SNR, nifedipine and bicuculline decreased KCC2 mRNA acutely and prevented further downregulation of KCC2 mRNA by estradiol. Estradiol therefore downregulates KCC2 mRNA in male PN15 SNR, by interacting with the GABA(A) receptor and L-VSCC signaling pathway.
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9
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Torres JM, Ortega E. Differential regulation of steroid 5alpha-reductase isozymes expression by androgens in the adult rat brain. FASEB J 2003; 17:1428-33. [PMID: 12890696 DOI: 10.1096/fj.02-1119com] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The enzyme 5alpha-reductase (5alpha-R) is present in many mammalian tissues, including the brain. The physiological importance of 5alpha-R in the brain derives from its capability to convert testosterone (T) to a more potent androgen, dihydrotestosterone (DHT), and to convert progesterone and deoxycorticosterone (DOC) to their respective 5alpha-reduced derivatives, precursors of allopregnanolone and tetrahydroDOC, potent allosteric modulators of the gamma-aminobutyric acid receptor (GABA(A)-R). 5alpha-R occurs as two isoforms, 5alpha-R type 1 (5alpha-R1) and 5alpha-R type 2 (5alpha-R2). We studied the effects of T and DHT on the mRNA levels of both 5alpha-R isozymes in the prefrontal cortex of the adult rat, using an accurate and precise method that combines the high specificity of one-step quantitative RT-PCR with the sensitivity of capillary electrophoresis. Our results demonstrate that both isozymes of 5alpha-R are expressed in the cerebral cortex of adult rats. The gene expression of 5alpha-R type 2 is under the positive control of T and DHT. The gene that codes for 5alpha-R type 1 is not constitutive, because its expression is negatively regulated by T and DHT. These results open up a new research line that may lead to a better understanding of the role of 5alpha-R isozymes in the physiology of the central nervous system.
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Affiliation(s)
- J M Torres
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Granada, Avda. de Madrid s/n, 18012 Granada, Spain
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10
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Herreros de Tejada P, Muñoz Tedó C. The decade 1989-1998 in Spanish psychology: an analysis of research in psychobiology. THE SPANISH JOURNAL OF PSYCHOLOGY 2001; 4:219-36. [PMID: 11723643 DOI: 10.1017/s113874160000576x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In this paper, we present an analysis of the research published during the 1989-1998 decade by tenured Spanish faculty members from the area of psychobiology. Database search and direct correspondence with the 110 faculty members rendered a list of 904 psychobiological papers. Classification and analysis of these papers led to the definition of at least 70 different research trends. Topics are grouped into several specific research areas: Learning and Memory; Development and Neural Plasticity; Emotion and Stress; Ethology; Neuropsychology; Sensory Processing; and Psychopharmacology. The international dissemination of this research, published in journals of high impact index, and the increasing number of papers are two noteworthy features.
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11
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Wong CC, Poon WH, Tsim TY, Wong EY, Leung MS. Gene expressions during the development and sexual differentiation of the olfactory bulb in rats. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2000; 119:187-94. [PMID: 10675768 DOI: 10.1016/s0165-3806(99)00173-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
In this study, expressions of cell-cycle-related genes: p53, retinoblastoma (Rb), p21, bcl-2(alpha), bcl-2(beta); protooncogene c-ski; glial cell marker protein gene S100beta; neurotransmitter gene, substance P and sexual-differentiation-related genes, androgen receptor (AR) and estrogen receptor beta (ER(beta)), are studied in the olfactory bulb of groups of both six female and six male rats at the ages of 3, 10, 20 and 40 days. Expressions of housekeeping genes such as beta-actin, cyclophilin and proliferating cell nuclear antigens (PCNA) are determined using reverse transcription polymerase chain reaction (RT-PCR) for the correction of unequal amount of cDNA added into the samples. Using labeled 32P-dCTP and Phosphorimager technology, relative abundance of radioactivities of the PCR products is obtained by dividing the radioactivity of each individual sample by the corresponding radioactivities of different housekeeping genes. Data evaluated by Two-way ANOVA indicate that only the bcl-2(alpha) gene expression is affected significantly by age, sex and their interactions no matter which of the three housekeeping genes is used for correction. When beta-actin was used for corrections, effects of age but not sex were found in the expressions of p53, Rb, p21, AR, ER(beta), substance P and S100beta genes, but not in bcl-2(beta), c-ski, cyclophilin and PCNA genes. While cyclophilin was used for corrections, only the p53, Rb, AR, ER(beta), substance P and S100beta but not the bcl-2(beta), p21, c-ski, PCNA and beta-actin genes are affected by age. They are all not influenced by sex of the animals. Only the AR, ER(beta) and S100beta genes are age-dependent when PCNA was used for the correction. The other gene expressions are not altered by sex, while the interactions of age and sex were found to be significantly affecting the bcl-2(beta) gene expression. Conclusively, developmental changes of the p53, Rb, AR, ER(beta), substance P and S100beta genes expressions are quite evidenced while only the bcl-2(alpha) gene seems to change significantly during the sexual differentiation of olfactory bulb in rats.
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Affiliation(s)
- C C Wong
- Department of Physiology, The Chinese University of Hong Kong, Shatin, NT, Hongkong, China.
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12
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Poletti A, Coscarella A, Negri-Cesi P, Colciago A, Celotti F, Martini L. 5 alpha-reductase isozymes in the central nervous system. Steroids 1998; 63:246-51. [PMID: 9618779 DOI: 10.1016/s0039-128x(98)00018-x] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The enzyme 5 alpha-reductase (5 alpha-R) activates several delta 4-3keto steroids to more potent derivatives which may also acquire new biological actions. Testosterone gives rise to the most potent natural androgen dihydrotestosterone (DHT), and progesterone to dihydroprogesterone (DHP), a precursor of the endogenous anxiolytic/anesthetic steroid tetrahydroprogesterone (THP). Two isoforms of 5 alpha-R, with a limited degree of homology, different biochemical properties and distinct tissue distribution have been cloned: 5 alpha-R type 1 and type 2. In androgen-dependent structures DHT is almost exclusively formed by 5 alpha-R type 2; 5 alpha-R type 1 is widely distributed in the body, with the highest levels in the liver, and may be involved in steroid catabolism. In the brain, the roles of the two isozymes are still largely unknown. This brief review will summarize recent experimental data from our laboratory which try to assign possible functional roles to the process of 5 alpha-reduction, and to the two 5 alpha-R isoforms in the CNS.
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Affiliation(s)
- A Poletti
- Istituto di Endocrinologia, Università di Milano, Italy
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13
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Melcangi RC, Poletti A, Cavarretta I, Celotti F, Colciago A, Magnaghi V, Motta M, Negri-Cesi P, Martini L. The 5alpha-reductase in the central nervous system: expression and modes of control. J Steroid Biochem Mol Biol 1998; 65:295-9. [PMID: 9699883 DOI: 10.1016/s0960-0760(98)00030-2] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The present paper will summarize two important aspects of the interactions between steroids and the brain, which have recently been studied in the authors' laboratory. In particular the paper will consider data on: (1) the significance of the two isoforms of the 5alpha-R during brain ontogenesis and development, and (2) the cross-talk between glial and neuronal elements, particularly in relation to the metabolism of sex hormones. (1) The data obtained have shown that the 5alpha-R type 1 enzyme is constitutively expressed in the rat CNS at all stages of brain development. Moreover, the expression of the 5alpha-R type 1 is similar in males and in females, and does not appear to be controlled by androgens. The gene expression of the 5alpha-R type 2 is totally different. This isoform appears to be expressed in the rat brain almost exclusively in the late fetal/early post-natal life and is controlled by testosterone. (2) The present data show that two cell lines derived respectively from a rat glioma (C6 cell line) and from a human astrocytoma (1321N1 cell line) are able to convert testosterone and progesterone into their corresponding 5alpha-reduced metabolites dihydrotestosterone and dihydroprogesterone. The possibility that secretory products of normal and tumoral brain cells might be able to influence steroid metabolism occurring in the two glial cell lines previously mentioned has been considered.
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Affiliation(s)
- R C Melcangi
- Department of Endocrinology, University of Milan, Italy
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14
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Celotti F, Negri-Cesi P, Poletti A. Steroid metabolism in the mammalian brain: 5alpha-reduction and aromatization. Brain Res Bull 1997; 44:365-75. [PMID: 9370201 DOI: 10.1016/s0361-9230(97)00216-5] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Several steroid molecules, including androgens, estrogens, progestagens, and corticostereroids, are able to modulate the brain development and functions. These compounds are not always active in their own natural molecular configuration but they often need to be transformed at the level of their target cells into 'active metabolites'. The two major metabolic pathways that transform steroids in the brain are: the 5alpha-reductase-3alpha-hydroxy-steroid dehydrogenase and the aromatase pathways. Both are present in the brain and probably exert specific roles in the mechanism of action of hormonal steroids. In this article we briefly review some important findings achieved in our own and in other laboratories concerning the cellular and subcellular brain distribution, development, regulation, cloning, and molecular characterization of the involved enzymes. In particular, the recent identification of two isoforms of the 5alpha-reductase, the type 1 and type 2, possessing different structural, biochemical, and distribution characteristics has attracted a considerable attention. The few data available on their brain distribution have been carefully considered. Finally, we have tried to focus on the role of the steroid metabolites in the brain, both when they interact with genomic and with membrane receptors. In particular, some unpublished observations on the effects of two 5alpha-reductase inhibitors on progesterone-induced anesthesia, a phenomenon mediated through the GABA(A) receptor, are presented.
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Affiliation(s)
- F Celotti
- Istituto di Endocrinologia, Università di Milano, Italy
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15
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Abstract
We investigated the effects of cocaine on the corpus callosum, the nerve fibre bundle that connects the bilateral cerebral hemispheres. Our experiments in rats confirmed that, in the control group, the mid-sagittal area of the corpus callosum in the adult male was significantly larger than this area in the female. Early postnatal exposure to cocaine abolished this sexual dimorphism, that is, cocaine-treated males had a significantly smaller callosal area than the control males. Cocaine induced no significant changes in the weight of the body or brain. There were no significant sex differences in the midline sagittal area of the anterior commissure, and no apparent effects of cocaine exposure were determined in this structure. These findings suggest that early postnatal exposure to cocaine abolishes the sexual differentiation of the corpus callosum in male rats.
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Affiliation(s)
- K Ojima
- Department of Legal Medicine, Kyoto University Faculty of Medicine, Japan
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16
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Affiliation(s)
- M D Madeira
- Department of Anatomy, Porto Medical School, Portugal
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17
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Pérez-Laso C, Valencia A, Rodríguez-Zafra M, Calés JM, Guillamón A, Segovia S. Perinatal administration of diazepam alters sexual dimorphism in the rat accessory olfactory bulb. Brain Res 1994; 634:1-6. [PMID: 8156379 DOI: 10.1016/0006-8993(94)90251-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The present study examines the effects of pre and/or early postnatal administration of diazepam on the mitral cell and on the light and dark granule cell populations in the sexually dimorphic accessory olfactory bulb of the rat. Quantitative differences related to sex were observed in the numbers of the three types of neurons, with vehicle males showing greater numbers of cells than vehicle females. The number of mitral cells in males decreased to the levels shown by female rats following prenatal and pre-postnatal diazepam treatments, whereas the DZ treatments did not affect the females. In addition, the diazepam administration during the prenatal, postnatal and pre-postnatal periods decreased the numbers of both light and dark granule cells in males, while these two granule cell subpopulations were not affected in diazepam treated females. These results indicate that perinatal administration of diazepam can alter the sexual dimorphism in the accessory olfactory bulb and that the GABAA/benzodiazepine receptor complex is involved in the sexual differentiation this part of the brain.
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Affiliation(s)
- C Pérez-Laso
- Departamento de Psicobiología, Universidad Nacional de Educación a Distancia, Ciudad Universitaria, Madrid, Spain
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18
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Collado P, Valencia A, Del Abril A, Rodríguez-Zafra M, Pérez-Laso C, Segovia S, Guillamón A. Effects of estradiol on the development of sexual dimorphism in the bed nucleus of the accessory olfactory tract in the rat. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 1993; 75:285-7. [PMID: 8261617 DOI: 10.1016/0165-3806(93)90033-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Orchidectomized males injected with a single dose of estradiol benzoate (EB) on the day of birth (D1) showed a volume and neuron number in the nucleus of the accessory olfactory tract (BAOT) similar to that of control males. However, orchidectomized males and those orchidectomized and given a single dose of DHT on D1 showed a decrease in BAOT volume and neuron number with respect to control males. These results support the notion that estradiol induces the morphological masculinization of this structure. The inability of DHT in counteracting the effect of orchidectomy is addressed taking into account the inhibitory action of androgens.
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Affiliation(s)
- P Collado
- Departamento de Psicobiología, Universidad Nacional de Educación a Distancia, Ciudad Universitaria, Madrid, Spain
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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.
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Affiliation(s)
- S Segovia
- Departamento de Psicobiología, Universidad Nacional de Educación a Distancia, Madrid, Spain
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