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Ågmo A. Androgen receptors and sociosexual behaviors in mammals: The limits of generalization. Neurosci Biobehav Rev 2024; 157:105530. [PMID: 38176634 DOI: 10.1016/j.neubiorev.2023.105530] [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: 10/18/2023] [Revised: 12/27/2023] [Accepted: 12/29/2023] [Indexed: 01/06/2024]
Abstract
Circulating testosterone is easily aromatized to estradiol and reduced to dihydrotestosterone in target tissues and elsewhere in the body. Thus, the actions of testosterone can be mediated either by the estrogen receptors, the androgen receptor or by simultaneous action at both receptors. To determine the role of androgens acting at the androgen receptor, we need to eliminate actions at the estrogen receptors. Alternatively, actions at the androgen receptor itself can be eliminated. In the present review, I will analyze the specific role of androgen receptors in male and female sexual behavior as well as in aggression. Some comments about androgen receptors and social recognition are also made. It will be shown that there are important differences between species, even between strains within a species, concerning the actions of the androgen receptor on the behaviors mentioned. This fact makes generalizations from one species to another or from one strain to another very risky. The existence of important species differences is often ignored, leading to many misunderstandings and much confusion.
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Affiliation(s)
- Anders Ågmo
- Department of Psychology, University of Tromsø, Norway.
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2
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Chu X, Snoeren E, Södersten P, Ågmo A. Sexual incentive motivation and male and female copulatory behavior in female rats given androgen from postnatal day 20. Physiol Behav 2021; 237:113460. [PMID: 33991538 DOI: 10.1016/j.physbeh.2021.113460] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 05/03/2021] [Accepted: 05/03/2021] [Indexed: 11/20/2022]
Abstract
Masculinization and feminization of rat sexual behavior has been supposed to occur during a short postnatal period. However, much data have made it evident that these processes may continue until adolescence. In the present study, we evaluated whether androgen treatment of females from postnatal day 20 and onwards could alter sexual motivation and behavior in a male direction. Juveniles were ovariectomized on day 20 and concurrently implanted with Silastic capsules containing either testosterone or dihydrotestosterone. Controls were implanted with an empty capsule. Tests for sexual incentive motivation and male sexual behavior were performed every fifth day when the females were between 50 and 75 days of age. At day 80, a test for female sexual behavior was performed. Females treated with testosterone approached a female sexual incentive far more than a male incentive, showing that sexual motivation had been changed in a male-like direction. Dihydrotestosterone had a similar, albeit smaller, effect. Females implanted with an empty capsule approached both incentives equally. Testosterone produced a high level of mounting behavior, whereas intromission-like behavioral patterns were rare and ejaculation-like behavior was absent. In the test for female sexual behavior, the testosterone-treated animals displayed a relatively high lordosis quotient, far above that displayed in females implanted with dihydrotestosterone or an empty capsule. It is concluded that treatment with an aromatizable androgen during the peripubertal-adolescent period masculinizes sexual motivation and partly sexual behavior. A non-aromatizable androgen weakly masculinize sexual motivation without enhancing male sexual behavior. It appears that simultaneous actions on androgen and estrogen receptors are needed for significant masculinization during the period studied here. Since the testosterone-treated females displayed lordosis, sexual behavior was not defeminized. In sum, these results suggest that sexual differentiation continues well into the peripubertal and adolescent periods.
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Affiliation(s)
- Xi Chu
- Department of Psychology, Norwegian University of Science and Technology, Trondheim, Norway
| | - Eelke Snoeren
- Department of Psychology, University of Tromsø, 9037 Tromsø, Norway
| | - Per Södersten
- Karolinska Institutet, Novum, S-141 01 Hudddinge, Sweden
| | - Anders Ågmo
- Department of Psychology, University of Tromsø, 9037 Tromsø, Norway.
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de Bournonville C, McGrath A, Remage-Healey L. Testosterone synthesis in the female songbird brain. Horm Behav 2020; 121:104716. [PMID: 32061616 PMCID: PMC7198340 DOI: 10.1016/j.yhbeh.2020.104716] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 02/07/2020] [Accepted: 02/08/2020] [Indexed: 01/19/2023]
Abstract
Decades of work have established the brain as a source of steroid hormones, termed 'neurosteroids'. The neurosteroid neuroestradiol is produced in discrete brain areas and influences cognition, sensory processing, reproduction, neurotransmission, and disease. A prevailing research focus on neuroestradiol has essentially ignored whether its immediate synthesis precursor - the androgen testosterone - is also dynamically regulated within the brain. Testosterone itself can rapidly influence neurophysiology and behavior, and there is indirect evidence that the female brain may synthesize significant quantities of testosterone to regulate cognition, reproduction, and behavior. In songbirds, acoustic communication is regulated by neuroestrogens. Neuroestrogens are rapidly synthetized in the caudomedial nidopallium (NCM) of the auditory cortex of zebra finches in response to song and can influence auditory processing and song discrimination. Here, we examined the in vivo dynamics of NCM levels of the neuroestrogen synthesis precursor, testosterone. Unlike estradiol, testosterone did not appear to fluctuate in the female NCM during song exposure. However, a substantial song-induced elevation of testosterone was revealed in the left hemisphere NCM of females when local aromatization (i.e., conversion to estrogens) was locally blocked. This elevation was eliminated when local androgen synthesis was concomitantly blocked. Further, no parallel elevation was observed in the circulation in response to song playback, consistent with a local, neural origin of testosterone synthesis. To our knowledge, this study provides the first direct demonstration that testosterone fluctuates rapidly in the brain in response to socially-relevant environmental stimuli. Our findings suggest therefore that locally-derived 'neuroandrogens' can dynamically influence brain function and behavior. SIGNIFICANCE STATEMENT: This study demonstrates that androgen synthesis occurs rapidly in vivo in the brain in response to social cues, in a lateralized manner. Specifically, testosterone synthesis occurs within the left secondary auditory cortex when female zebra finches hear male song. Therefore, testosterone could act as a neuromodulator to rapidly shape sensory processing. Androgens have been linked to functions such as the control of female libido, and many steroidal drugs used for contraception, anti-cancer treatments, and sexual dysfunction likely influence the brain synthesis and action of testosterone. The current findings therefore establish a clear role for androgen synthesis in the female brain with implications for understanding neural circuit function and behavior in animals, including humans.
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Affiliation(s)
- Catherine de Bournonville
- Center for Neuroendocrine Studies, University of Massachusetts, Amherst, MA 01003, United States of America.
| | - Aiden McGrath
- Center for Neuroendocrine Studies, University of Massachusetts, Amherst, MA 01003, United States of America
| | - Luke Remage-Healey
- Center for Neuroendocrine Studies, University of Massachusetts, Amherst, MA 01003, United States of America.
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On the role of brain aromatase in females: why are estrogens produced locally when they are available systemically? J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2017; 204:31-49. [PMID: 29086012 DOI: 10.1007/s00359-017-1224-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 10/12/2017] [Accepted: 10/17/2017] [Indexed: 01/27/2023]
Abstract
The ovaries are often thought of as the main and only source of estrogens involved in the regulation of female behavior. However, aromatase, the key enzyme for estrogen synthesis, although it is more abundant in males, is expressed and active in the brain of females where it is regulated by similar mechanisms as in males. Early work had shown that estrogens produced in the ventromedial hypothalamus are involved in the regulation of female sexual behavior in musk shrews. However, the question of the role of central aromatase in general had not received much attention until recently. Here, I will review the emerging concept that central aromatization plays a role in the regulation of physiological and behavioral endpoints in females. The data support the notion that in females, brain aromatase is not simply a non-functional evolutionary vestige, and provide support for the importance of locally produced estrogens for brain function in females. These observations should also have an impact for clinical research.
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Blasberg ME, Robinson S, Henderson LP, Clark AS. Inhibition of estrogen-induced sexual receptivity by androgens: role of the androgen receptor. Horm Behav 1998; 34:283-93. [PMID: 9878277 DOI: 10.1006/hbeh.1998.1484] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Both naturally occurring and synthetic androgens have been shown to inhibit estrogen-induced sexual receptivity when administered to ovariectomized (OVX) rats. The mechanisms by which androgens exert these effects, however, remain unclear. Experiments were conducted to determine the role of the androgen receptor in the inhibition of estrogen-induced sexual receptivity in OVX rats by using flutamide, an androgen receptor antagonist. In each experiment, OVX Long-Evans rats received 6 consecutive days of estradiol benzoate (EB; 2.0 microg/day) followed by 15 days of EB concurrent with flutamide (10. 0 mg/kg; twice daily) or the vehicle and one of the following androgens or the vehicle: dihydrotestosterone propionate (7.5 mg/kg), 3alpha-androstanediol (3.75 mg/kg), 17alpha-methyltestosterone (7.5 mg/kg), stanozolol (7.5 mg/kg), or nandrolone decanoate (7.5 mg/kg). On Day 15, all female rats received progesterone (P; 1.0 mg/rat) 4 h before testing. Tests for sexual receptivity were conducted on Days 3, 6, 14, and 15 of androgen/flutamide treatment. Each androgen inhibited sexual receptivity as expected, and concurrent treatment with flutamide reversed the inhibitory effects of all androgens on sexual receptivity on all test days. High levels of sexual receptivity were displayed in response to P on Day 15, regardless of experimental treatment. These results suggest that naturally occurring and synthetic androgens act at the androgen receptor to inhibit estrogen-induced sexual receptivity in OVX rats.
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Affiliation(s)
- M E Blasberg
- Department of Psychology, Dartmouth College, Hanover, New Hampshire 03755, USA
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Clark AS, Blasberg ME, Brandling-Bennett EM. Stanozolol, oxymetholone, and testosterone cypionate effects on the rat estrous cycle. Physiol Behav 1998; 63:287-95. [PMID: 9423971 DOI: 10.1016/s0031-9384(97)00443-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Anabolic-androgenic steroid (AAS) effects on the estrous cycle of adult Long-Evans rats were examined in four different experiments. Sexual receptivity, vaginal cytology, and body weight were monitored throughout two-week baseline, AAS treatment, and recovery periods. In Experiments 1-3, rats were administered stanozolol, oxymetholone, or testosterone cypionate within dose ranges selected to mimic the human abuse levels of each compound. In these studies, the highest doses of stanozolol (5 mg/kg), oxymetholone (12 mg/kg), or testosterone cypionate (7.5 mg/kg) disrupted the cyclical display of sexual receptivity and vaginal estrus. To compare effects on estrous cyclicity across AAS compounds, rats in Experiment 4 received a single dose (7.5 mg/kg) of each compound for 2 weeks. At the 7.5 mg/kg dose, all AAS compounds interfered with the cyclical display of vaginal estrus, although effects on sexual receptivity were not uniform. No striking AAS effects on body weight were seen in any experiment. The short-term administration of AAS compounds at high doses disrupts female neuroendocrine function in rats.
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Affiliation(s)
- A S Clark
- Department of Psychology, Dartmouth College, Hanover, NH 03755, USA.
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Brand T, Slob AK. Perinatal flutamide and mounting and lordosis behavior in adult female Wistar and Sprague-Dawley rats. Behav Brain Res 1991; 44:43-51. [PMID: 1910570 DOI: 10.1016/s0166-4328(05)80238-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The present study was designed to investigate the possible role of perinatal androgens acting via the androgen receptor, as opposed to the estrogen receptor, for the differentiation of adult mounting and lordosis behavior in female rats. Female Wistar (W) and Sprague-Dawley (SD) rats were exposed to the anti-androgen flutamide prenatally (days 11-22 of pregnancy) and/or neonatally (days 1-10). The females were ovariectomized in adulthood and repeatedly tested for mounting and lordosis behavior. Flutamide, given both pre- and neonatally to SD rats, reduced adult T-induced female mounting. Flutamide administered only prenatally or only neonatally did not lower adult mounting behavior of SD rats. Mounting behavior of female W rats, following pre- and/or neonatal flutamide treatment was not affected. Lordosis behavior was also not altered by perinatal flutamide treatment of either strain. The results of the present study, no effect of prenatal flutamide, do not support the hypothesis that female rats require prenatal androgen receptor-mediated actions of testosterone in the organization of neural tissues for the occurrence of adult mounting and lordosis behavior. Only in SD rats androgenic organization of adult mounting behavior via the androgen receptor seems to occur both pre- and neonatally. Since clear behavioral effects of prenatal flutamide treatment have been published earlier in Long-Evans females, we suggest strain differences in sensitivity for perinatal androgenization in female rats. Future research into that possibility is needed.
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Affiliation(s)
- T Brand
- Department of Endocrinology and Reproduction, Faculty of Medicine and Health Sciences, Erasmus University, Rotterdam, The Netherlands
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Erskine MS. Effects of an anti-androgen and 5 alpha-reductase inhibitors on estrus duration in the cycling female rat. Physiol Behav 1983; 30:519-24. [PMID: 6683842 DOI: 10.1016/0031-9384(83)90214-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Five experiments examined the role of circulating androgens in the control of sexual behavior (lordosis) in the intact cycling rat. The androgen receptor blocker, flutamide (FLU), was administered daily to cycling rats beginning on the day of estrus, and lordotic responsiveness was measured on the 2nd subsequent proestrus day and on the day of estrus. FLU-treated females showed significantly higher levels of lordosis throughout the end of the period of estrus than controls (Experiment 1). Neither the maximal levels of lordosis seen on the evening of proestrus nor the time of onset of estrous responsiveness during the preceeding afternoon were affected by FLU (Experiment 2). Serum estradiol concentrations seen on the morning of proestrus (Experiment 3) did not differ between FLU- and vehicle-treated animals. The weak 5 alpha-reductase inhibitor, testosterone-17 beta-carboxylic acid (17 beta C), prolonged slightly, but did not significantly lengthen, the period of estrus (Experiment 4), while the highly potent steroidal 5 alpha-reductase inhibitor, 4 MA, significantly increased the rate at which estrous behavior declined on the day of estrus (Experiment 5). Circulating androgens do not appear to affect the maximal level of sexual receptivity displayed nor the time of estrus onset; however, they may govern the duration of the period of estrus by influencing the rate of estrus termination.
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Doering CH, Gladue BA. 5 alpha-androstane-3 beta, 17 beta-diol binds to androgen and estrogen receptors without activating copulatory behavior in female rats. Pharmacol Biochem Behav 1982; 16:837-40. [PMID: 7089040 DOI: 10.1016/0091-3057(82)90244-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The ability of the androgen metabolite 5 alpha-androstane-3 beta, 17 beta-diol (3 beta-A-diol) to facilitate copulatory behavior was assessed directly in adult ovariectomized rats. Neither the highest dosage of 5 mg/day for three days, nor 2 mg/day for 15 days could induce lordosis behavior in females that displayed typically high lordosis quotients with low dosages of estradiol (E). Furthermore, prolonged administration of 5 alpha-dihydrotestosterone (DHT) induced a low but significant level of male-typical mounting behavior in females, whereas 3 beta-a-diol administered for 20 days (2 mg/day) had no effect on mounting behavior. However, this reduced androgen metabolite did compete moderately well for DHT and E binding sites on androgen and estrogen receptors respectively in hypothalamic cytosol preparations. We conclude that in spite of its ability to bind to these receptors in the brain 3 beta-A-diol, a major metabolite of DHT, is totally inert with respect to sexual behavior.
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Gladue BA, Clemens LG. Masculinization diminished by disruption of prenatal estrogen biosynthesis in male rats. Physiol Behav 1980; 25:589-93. [PMID: 7208655 DOI: 10.1016/0031-9384(80)90126-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Landau IT. Facilitation of male sexual behavior in adult male rats by the aromatization inhibitor, 1,4,6-androstatriene-3,17-dione (ATD). Physiol Behav 1980; 25:173-7. [PMID: 7413827 DOI: 10.1016/0031-9384(80)90203-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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12
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Krey LC, Kamel F, McEwen BS. Parameters of neuroendocrine aromatization and estrogen receptor occupation in the male rat. Brain Res 1980; 193:277-83. [PMID: 7378821 DOI: 10.1016/0006-8993(80)90967-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Adkins EK, Boop JJ, Koutnik DL, Morris JB, Pniewski EE. Further evidence that androgen aromatization is essential for the activation of copulation in male quail. Physiol Behav 1980; 24:441-6. [PMID: 7375563 DOI: 10.1016/0031-9384(80)90233-4] [Citation(s) in RCA: 144] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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McEwen BS, Lieberburg I, Chaptal C, Davis PG, Krey LC, MacLusky NJ, Roy EJ. Attenuating the defeminization of the neonatal rat brain: mechanisms of action of cyproterone acetate, 1,4,6-androstatriene-3,17,-dione and a synthetic progestin, R5020. Horm Behav 1979; 13:269-81. [PMID: 575953 DOI: 10.1016/0018-506x(79)90044-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Gray JM, Nunez AA, Siegel LI, Wade GN. Effects of testosterone on body weight and adipose tissue: role of aromatization. Physiol Behav 1979; 23:465-9. [PMID: 504438 DOI: 10.1016/0031-9384(79)90045-3] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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