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Demas GE, Munley KM, Jasnow AM. A seasonal switch hypothesis for the neuroendocrine control of aggression. Trends Endocrinol Metab 2023; 34:799-812. [PMID: 37722999 DOI: 10.1016/j.tem.2023.08.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 08/22/2023] [Accepted: 08/23/2023] [Indexed: 09/20/2023]
Abstract
Aggression is a well-studied social behavior that is universally exhibited by animals across a wide range of contexts. Prevailing knowledge suggests gonadal steroids primarily mediate aggression; however, this is based mainly on studies of male-male aggression in laboratory rodents. When males and females of other species, including humans, are examined, a positive relationship between gonadal steroids and aggression is less substantiated. For instance, hamsters housed in short 'winter-like' days show increased aggression compared with long-day housed hamsters, despite relatively low circulating gonadal steroids. These results suggest alternative, non-gonadal mechanisms controlling aggression. Here, we propose the seasonal switch hypothesis, which employs a multidisciplinary approach to describe how seasonal variation in extra-gonadal steroids, orchestrated by melatonin, drives context-specific changes in aggression.
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Affiliation(s)
- Gregory E Demas
- Department of Biology, Program in Neuroscience, and Program in Animal Behavior, Indiana University, Bloomington, IN 47405, USA.
| | - Kathleen M Munley
- Department of Psychology, University of Houston, Houston, TX 77204, USA
| | - Aaron M Jasnow
- Department of Pharmacology, Physiology & Neuroscience, University of South Carolina School of Medicine, Columbia, SC 29209, USA
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Aspesi D, Bass N, Kavaliers M, Choleris E. The role of androgens and estrogens in social interactions and social cognition. Neuroscience 2023:S0306-4522(23)00151-3. [PMID: 37080448 DOI: 10.1016/j.neuroscience.2023.03.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 03/02/2023] [Accepted: 03/28/2023] [Indexed: 04/22/2023]
Abstract
Gonadal hormones are becoming increasingly recognized for their effects on cognition. Estrogens, in particular, have received attention for their effects on learning and memory that rely upon the functioning of various brain regions. However, the impacts of androgens on cognition are relatively under investigated. Testosterone, as well as estrogens, have been shown to play a role in the modulation of different aspects of social cognition. This review explores the impact of testosterone and other androgens on various facets of social cognition including social recognition, social learning, social approach/avoidance, and aggression. We highlight the relevance of considering not only the actions of the most commonly studied steroids (i.e., testosterone, 17β-estradiol, and dihydrotestosterone), but also that of their metabolites and precursors, which interact with a plethora of different receptors and signalling molecules, ultimately modulating behaviour. We point out that it is also essential to investigate the effects of androgens, their precursors and metabolites in females, as prior studies have mostly focused on males. Overall, a comprehensive analysis of the impact of steroids such as androgens on behaviour is fundamental for a full understanding of the neural mechanisms underlying social cognition, including that of humans.
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Affiliation(s)
- Dario Aspesi
- Department of Psychology and Neuroscience Program, University of Guelph
| | - Noah Bass
- Department of Psychology and Neuroscience Program, University of Guelph
| | - Martin Kavaliers
- Department of Psychology and Neuroscience Program, University of Guelph; Department of Psychology, University of Western Ontario, London, Canada; Graduate Program in Neuroscience, University of Western Ontario, London, Canada
| | - Elena Choleris
- Department of Psychology and Neuroscience Program, University of Guelph.
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Munley KM, Han Y, Lansing MX, Demas GE. Winter madness: Melatonin as a neuroendocrine regulator of seasonal aggression. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2022; 337:873-889. [PMID: 35451566 PMCID: PMC9587138 DOI: 10.1002/jez.2601] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 03/16/2022] [Accepted: 04/07/2022] [Indexed: 12/25/2022]
Abstract
Individuals of virtually all vertebrate species are exposed to annual fluctuations in the deterioration and renewal of their environments. As such, organisms have evolved to restrict energetically expensive processes and activities to a specific time of the year. Thus, the precise timing of physiology and behavior is critical for individual reproductive success and subsequent fitness. Although the majority of research on seasonality has focused on seasonal reproduction, pronounced fluctuations in other non-reproductive social behaviors, including agonistic behaviors (e.g., aggression), also occur. To date, most studies that have investigated the neuroendocrine mechanisms underlying seasonal aggression have focused on the role of photoperiod (i.e., day length); prior findings have demonstrated that some seasonally breeding species housed in short "winter-like" photoperiods display increased aggression compared with those housed in long "summer-like" photoperiods, despite inhibited reproduction and low gonadal steroid levels. While fewer studies have examined how the hormonal correlates of environmental cues regulate seasonal aggression, our previous work suggests that the pineal hormone melatonin acts to increase non-breeding aggression in Siberian hamsters (Phodopus sungorus) by altering steroid hormone secretion. This review addresses the physiological and cellular mechanisms underlying seasonal plasticity in aggressive and non-aggressive social behaviors, including a key role for melatonin in facilitating a "neuroendocrine switch" to alternative physiological mechanisms of aggression across the annual cycle. Collectively, these studies highlight novel and important mechanisms by which melatonin regulates aggressive behavior in vertebrates and provide a more comprehensive understanding of the neuroendocrine bases of seasonal social behaviors broadly.
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Affiliation(s)
- Kathleen M. Munley
- Department of Biology and Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, IN 47405, USA
| | - Yuqi Han
- Department of Biology and Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, IN 47405, USA
| | - Matt X. Lansing
- Department of Biology and Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, IN 47405, USA
| | - Gregory E. Demas
- Department of Biology and Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, IN 47405, USA
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Munley KM, Rendon NM, Demas GE. Neural Androgen Synthesis and Aggression: Insights From a Seasonally Breeding Rodent. Front Endocrinol (Lausanne) 2018; 9:136. [PMID: 29670576 PMCID: PMC5893947 DOI: 10.3389/fendo.2018.00136] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Accepted: 03/15/2018] [Indexed: 11/24/2022] Open
Abstract
Aggression is an essential social behavior that promotes survival and reproductive fitness across animal systems. While research on the neuroendocrine mechanisms underlying this complex behavior has traditionally focused on the classic neuroendocrine model, in which circulating gonadal steroids are transported to the brain and directly mediate neural circuits relevant to aggression, recent studies have suggested that this paradigm is oversimplified. Work on seasonal mammals that exhibit territorial aggression outside of the breeding season, such as Siberian hamsters (Phodopus sungorus), has been particularly useful in elucidating alternate mechanisms. These animals display elevated levels of aggression during the non-breeding season, in spite of gonadal regression and reduced levels of circulating androgens. Our laboratory has provided considerable evidence that the adrenal hormone precursor dehydroepiandrosterone (DHEA) is important in maintaining aggression in both male and female Siberian hamsters during the non-breeding season, a mechanism that appears to be evolutionarily-conserved in some seasonal rodent and avian species. This review will discuss research on the neuroendocrine mechanisms of aggression in Siberian hamsters, a species that displays robust neural, physiological, and behavioral changes on a seasonal basis. Furthermore, we will address how these findings support a novel neuroendocrine pathway for territorial aggression in seasonal animals, in which adrenal DHEA likely serves as an essential precursor for neural androgen synthesis during the non-breeding season.
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Scotti MAL, Rendon NM, Greives TJ, Romeo RD, Demas GE. Short-day aggression is independent of changes in cortisol or glucocorticoid receptors in male Siberian hamsters (Phodopus sungorus). ACTA ACUST UNITED AC 2015; 323:331-41. [DOI: 10.1002/jez.1922] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 01/21/2015] [Indexed: 11/07/2022]
Affiliation(s)
| | - Nikki M. Rendon
- Department of Biology; Program in Neuroscience; Center for the Integrative Study of Animal Behavior, Indiana University; Bloomington Indiana
| | - Timothy J. Greives
- Department of Biological Sciences; North Dakota State University; Fargo North Dakota
| | - Russell D. Romeo
- Department of Psychology and Neuroscience and Behavior Program; Barnard College of Columbia University; New York New York
| | - Gregory E. Demas
- Department of Biology; Program in Neuroscience; Center for the Integrative Study of Animal Behavior, Indiana University; Bloomington Indiana
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French JA, Mustoe AC, Cavanaugh J, Birnie AK. The influence of androgenic steroid hormones on female aggression in 'atypical' mammals. Philos Trans R Soc Lond B Biol Sci 2013; 368:20130084. [PMID: 24167314 PMCID: PMC3826213 DOI: 10.1098/rstb.2013.0084] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Dimorphism on dominance and agonistic behaviour in mammals tends to be strongly biased toward males. In this review, we focus on a select few species of mammals in which females are as or more aggressive than males, and/or are dominant to males, and explore the role of androgenic hormones in mediating this important difference. While the data are not as clear-cut as those published on traditional laboratory mammals, our review highlights important endocrine substrates for both organizational and activational influences of steroids on female aggressive behaviour. We highlight areas in which further observations and experiments are crucial, especially the potential facilitative effects of androgens on female aggression. Finally, new and innovative techniques, including molecular genetics and receptor pharmacology, portend important insights into the ways in which androgenic hormones regulate aggressive behaviour in 'atypical' female mammals.
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Affiliation(s)
- Jeffrey A. French
- Department of Psychology, Callitrichid Research Center, University of Nebraska at Omaha, Omaha, NE 68182, USA
- Department of Biology, University of Nebraska at Omaha, Omaha, NE 68182, USA
| | - Aaryn C. Mustoe
- Department of Psychology, Callitrichid Research Center, University of Nebraska at Omaha, Omaha, NE 68182, USA
| | - Jon Cavanaugh
- Department of Psychology, Callitrichid Research Center, University of Nebraska at Omaha, Omaha, NE 68182, USA
| | - Andrew K. Birnie
- Department of Psychology, Callitrichid Research Center, University of Nebraska at Omaha, Omaha, NE 68182, USA
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Scotti MAL, Belén J, Jackson JE, Demas GE. The role of androgens in the mediation of seasonal territorial aggression in male Siberian hamsters (Phodopus sungorus). Physiol Behav 2008; 95:633-40. [DOI: 10.1016/j.physbeh.2008.09.009] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2008] [Revised: 09/04/2008] [Accepted: 09/05/2008] [Indexed: 11/17/2022]
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Soma KK, Scotti MAL, Newman AEM, Charlier TD, Demas GE. Novel mechanisms for neuroendocrine regulation of aggression. Front Neuroendocrinol 2008; 29:476-89. [PMID: 18280561 DOI: 10.1016/j.yfrne.2007.12.003] [Citation(s) in RCA: 159] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2007] [Revised: 10/02/2007] [Accepted: 12/25/2007] [Indexed: 11/19/2022]
Abstract
In 1849, Berthold demonstrated that testicular secretions are necessary for aggressive behavior in roosters. Since then, research on the neuroendocrinology of aggression has been dominated by the paradigm that the brain receives gonadal hormones, primarily testosterone, which modulate relevant neural circuits. While this paradigm has been extremely useful, recent studies reveal important alternatives. For example, most vertebrate species are seasonal breeders, and many species show aggression outside of the breeding season, when gonads are regressed and circulating testosterone levels are typically low. Studies in birds and mammals suggest that an adrenal androgen precursor-dehydroepiandrosterone (DHEA)-may be important for the expression of aggression when gonadal testosterone synthesis is low. Circulating DHEA can be metabolized into active sex steroids within the brain. Another possibility is that the brain can autonomously synthesize sex steroids de novo from cholesterol, thereby uncoupling brain steroid levels from circulating steroid levels. These alternative neuroendocrine mechanisms to provide sex steroids to specific neural circuits may have evolved to avoid the "costs" of high circulating testosterone during particular seasons. Physiological indicators of season (e.g., melatonin) may allow animals to switch from one neuroendocrine mechanism to another across the year. Such mechanisms may be important for the control of aggression in many vertebrate species, including humans.
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Affiliation(s)
- Kiran K Soma
- Department of Psychology, Graduate Program in Neuroscience, University of British Columbia, Vancouver, BC, Canada V6T 1Z4.
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Abstract
Animal models indicate that the neuroactive steroids 3alpha,5alpha-THP (allopregnanolone) and 3alpha,5alpha-THDOC (allotetrahydroDOC) are stress responsive, serving as homeostatic mechanisms in restoring normal GABAergic and hypothalamic-pituitary-adrenal (HPA) function following stress. While neurosteroid increases to stress are adaptive in the short term, animal models of chronic stress and depression find lower brain and plasma neurosteroid concentrations and alterations in neurosteroid responses to acute stressors. It has been suggested that disruption in this homeostatic mechanism may play a pathogenic role in some psychiatric disorders related to stress. In humans, neurosteroid depletion is consistently documented in patients with current depression and may reflect their greater chronic stress. Women with the depressive disorder, premenstrual dysphoric disorder (PMDD), have greater daily stress and a greater rate of traumatic stress. While results on baseline concentrations of neuroactive steroids in PMDD are mixed, PMDD women have diminished functional sensitivity of GABA(A) receptors and our laboratory has found blunted allopregnanolone responses to mental stress relative to non-PMDD controls. Similarly, euthymic women with histories of clinical depression, which may represent a large proportion of PMDD women, show more severe dysphoric mood symptoms and blunted allopregnanolone responses to stress versus never-depressed women. It is suggested that failure to mount an appropriate allopregnanolone response to stress may reflect the price of repeated biological adaptations to the increased life stress that is well documented in depressive disorders and altered allopregnanolone stress responsivity may also contribute to the dysregulation seen in HPA axis function in depression.
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Affiliation(s)
- Susan S Girdler
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7175, United States.
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Lu SF, Mo Q, Hu S, Garippa C, Simon NG. Dehydroepiandrosterone upregulates neural androgen receptor level and transcriptional activity. ACTA ACUST UNITED AC 2003; 57:163-71. [PMID: 14556282 DOI: 10.1002/neu.10260] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The mechanism of action of dehydroepiandrosterone (DHEA), a neuroactive neurosteroid synthesized in the brains of humans and other mammals, has not been fully characterized in the adult brain. Although well known for modulatory effects on GABA(A), NMDA, and sigma(1) receptors, studies in both CNS and peripheral target cells suggest that DHEA also may exert genomic effects via the androgen receptor (AR). The current study tested the hypothesis that DHEA was capable of producing androgenic effects in the CNS by assaying its ability to induce three characteristic effects of an androgenic compound. These included the ability to upregulate neural AR protein level in mouse brain and immortalized GT1-7 hypothalamic cells, the capacity to induce transcriptional activity through AR in CV-1 cells transfected with an MMTV-ARE-CAT reporter, and competition for recombinant AR binding in a radioligand binding assay. The results showed that DHEA treatment significantly augmented AR both in vivo and in vitro, and that this effect was not blocked by trilostane (TRIL), a known 3beta-hydroxysteroid dehydrogenase (3beta-HSD) inhibitor. DHEA also promoted AR-mediated CAT reporter expression and competed with dihydrotestosterone (DHT) for binding to recombinant AR in a cell-free system. These data indicate that DHEA possesses intrinsic androgenic activity that is potentially independent of metabolic conversion to other androgens, and that it can affect gene function through the AR. In combination with its modulation of neurotransmitter receptors at the cell membrane level, the findings suggest that the mechanism of action of DHEA in the brain can involve a "crosstalk" cellular signaling system that involves both nongenomic and genomic components.
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Affiliation(s)
- Shi-Fang Lu
- Department of Biological Sciences, Lehigh University, 111 Research Drive, Lehigh University, Bethlehem, Pennsylvania 18015, USA.
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