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Quintana L, Jalabert C, Fokidis HB, Soma KK, Zubizarreta L. Neuroendocrine Mechanisms Underlying Non-breeding Aggression: Common Strategies Between Birds and Fish. Front Neural Circuits 2021; 15:716605. [PMID: 34393727 PMCID: PMC8358322 DOI: 10.3389/fncir.2021.716605] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 07/06/2021] [Indexed: 11/13/2022] Open
Abstract
Aggression is an adaptive behavior that plays an important role in gaining access to limited resources. Aggression may occur uncoupled from reproduction, thus offering a valuable context to further understand its neural and hormonal regulation. This review focuses on the contributions from song sparrows (Melospiza melodia) and the weakly electric banded knifefish (Gymnotus omarorum). Together, these models offer clues about the underlying mechanisms of non-breeding aggression, especially the potential roles of neuropeptide Y (NPY) and brain-derived estrogens. The orexigenic NPY is well-conserved between birds and teleost fish, increases in response to low food intake, and influences sex steroid synthesis. In non-breeding M. melodia, NPY increases in the social behavior network, and NPY-Y1 receptor expression is upregulated in response to a territorial challenge. In G. omarorum, NPY is upregulated in the preoptic area of dominant, but not subordinate, individuals. We hypothesize that NPY may signal a seasonal decrease in food availability and promote non-breeding aggression. In both animal models, non-breeding aggression is estrogen-dependent but gonad-independent. In non-breeding M. melodia, neurosteroid synthesis rapidly increases in response to a territorial challenge. In G. omarorum, brain aromatase is upregulated in dominant but not subordinate fish. In both species, the dramatic decrease in food availability in the non-breeding season may promote non-breeding aggression, via changes in NPY and/or neurosteroid signaling.
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Affiliation(s)
- Laura Quintana
- Unidad Bases Neurales de la Conducta, Departamento de Neurofisiología Celular y Molecular, Instituto de Investigaciones Biológicas Clemente Estable, Ministerio de Educación y Cultura, Montevideo, Uruguay
| | - Cecilia Jalabert
- Department of Zoology, The University of British Columbia, Vancouver, BC, Canada
| | - H Bobby Fokidis
- Department of Biology, Rollins College, Winter Park, FL, United States
| | - Kiran K Soma
- Department of Zoology, The University of British Columbia, Vancouver, BC, Canada.,Department of Psychology, The University of British Columbia, Vancouver, BC, Canada
| | - Lucia Zubizarreta
- Unidad Bases Neurales de la Conducta, Departamento de Neurofisiología Celular y Molecular, Instituto de Investigaciones Biológicas Clemente Estable, Ministerio de Educación y Cultura, Montevideo, Uruguay.,Laboratorio de Neurofisiología Celular y Sináptica, Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
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Termignoni-Garcia F, Louder MIM, Balakrishnan CN, O’Connell L, Edwards SV. Prospects for sociogenomics in avian cooperative breeding and parental care. Curr Zool 2020; 66:293-306. [PMID: 32440290 PMCID: PMC7233861 DOI: 10.1093/cz/zoz057] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 11/20/2019] [Indexed: 01/08/2023] Open
Abstract
For the last 40 years, the study of cooperative breeding (CB) in birds has proceeded primarily in the context of discovering the ecological, geographical, and behavioral drivers of helping. The advent of molecular tools in the early 1990s assisted in clarifying the relatedness of helpers to those helped, in some cases, confirming predictions of kin selection theory. Methods for genome-wide analysis of sequence variation, gene expression, and epigenetics promise to add new dimensions to our understanding of avian CB, primarily in the area of molecular and developmental correlates of delayed breeding and dispersal, as well as the ontogeny of achieving parental status in nature. Here, we outline key ways in which modern -omics approaches, in particular genome sequencing, transcriptomics, and epigenetic profiling such as ATAC-seq, can be used to add a new level of analysis of avian CB. Building on recent and ongoing studies of avian social behavior and sociogenomics, we review how high-throughput sequencing of a focal species or clade can provide a robust foundation for downstream, context-dependent destructive and non-destructive sampling of specific tissues or physiological states in the field for analysis of gene expression and epigenetics. -Omics approaches have the potential to inform not only studies of the diversification of CB over evolutionary time, but real-time analyses of behavioral interactions in the field or lab. Sociogenomics of birds represents a new branch in the network of methods used to study CB, and can help clarify ways in which the different levels of analysis of CB ultimately interact in novel and unexpected ways.
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Affiliation(s)
- Flavia Termignoni-Garcia
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
- Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138, USA
| | - Matthew I M Louder
- International Research Center for Neurointelligence, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | | | - Lauren O’Connell
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Scott V Edwards
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
- Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138, USA
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3
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Munley KM, Deyoe JE, Ren CC, Demas GE. Melatonin mediates seasonal transitions in aggressive behavior and circulating androgen profiles in male Siberian hamsters. Horm Behav 2020; 117:104608. [PMID: 31669179 PMCID: PMC6980702 DOI: 10.1016/j.yhbeh.2019.104608] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 09/30/2019] [Accepted: 10/03/2019] [Indexed: 01/12/2023]
Abstract
Some seasonally-breeding animals are more aggressive during the short, "winter-like" days (SD) of the non-breeding season, despite gonadal regression and reduced circulating androgen levels. While the mechanisms underlying SD increases in aggression are not well understood, previous work from our lab suggests that pineal melatonin (MEL) and the adrenal androgen dehydroepiandrosterone (DHEA) are important in facilitating non-breeding aggression in Siberian hamsters (Phodopus sungorus). To characterize the role of MEL in modulating seasonal transitions in aggressive behavior, we housed male hamsters in long days (LD) or SD, treated them with timed MEL (M) or saline injections, and measured aggression after 3, 6, and 9 weeks. Furthermore, to assess whether MEL mediates seasonal shifts in gonadal and adrenal androgen synthesis, serum testosterone (T) and DHEA concentrations were quantified 36 h before and immediately following an aggressive encounter. LD-M and SD males exhibited similar physiological and behavioral responses to treatment. Specifically, both LD-M and SD males displayed higher levels of aggression than LD males and reduced circulating DHEA and T in response to an aggressive encounter, whereas LD males elevated circulating androgens. Interestingly, LD and SD males exhibited distinct relationships between circulating androgens and aggressive behavior, in which changes in serum T following an aggressive interaction (∆T) were negatively correlated with aggression in LD males, while ∆DHEA was positively correlated with aggression in SD males. Collectively, these findings suggest that SD males transition from synthesis to metabolism of circulating androgens following an aggressive encounter, a mechanism that is modulated by MEL.
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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.
| | - Jessica E Deyoe
- Department of Biology and Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, IN 47405, USA.
| | - Clarissa C Ren
- 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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4
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Heimovics SA, Merritt JR, Jalabert C, Ma C, Maney DL, Soma KK. Rapid effects of 17β-estradiol on aggressive behavior in songbirds: Environmental and genetic influences. Horm Behav 2018; 104:41-51. [PMID: 29605636 PMCID: PMC6344317 DOI: 10.1016/j.yhbeh.2018.03.010] [Citation(s) in RCA: 17] [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: 02/06/2018] [Revised: 03/27/2018] [Accepted: 03/28/2018] [Indexed: 02/06/2023]
Abstract
Contribution to Special Issue on Fast effects of steroids. 17β-estradiol (E2) has numerous rapid effects on the brain and behavior. This review focuses on the rapid effects of E2 on aggression, an important social behavior, in songbirds. First, we highlight the contributions of studies on song sparrows, which reveal that seasonal changes in the environment profoundly influence the capacity of E2 to rapidly alter aggressive behavior. E2 administration to male song sparrows increases aggression within 20 min in the non-breeding season, but not in the breeding season. Furthermore, E2 rapidly modulates several phosphoproteins in the song sparrow brain. In particular, E2 rapidly affects pCREB in the medial preoptic nucleus, in the non-breeding season only. Second, we describe studies of the white-throated sparrow, which reveal how a genetic polymorphism may influence the rapid effects of E2 on aggression. In this species, a chromosomal rearrangement that includes ESR1, which encodes estrogen receptor α (ERα), affects ERα expression in the brain and the ability of E2 to rapidly promote aggression. Third, we summarize studies showing that aggressive interactions rapidly affect levels of E2 and other steroids, both in the blood and in specific brain regions, and the emerging potential for steroid profiling by liquid chromatography tandem mass spectrometry (LC-MS/MS). Such studies of songbirds demonstrate the value of an ethologically informed approach, in order to reveal how steroids act rapidly on the brain to alter naturally-occurring behavior.
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Affiliation(s)
| | | | - Cecilia Jalabert
- University of British Columbia, Department of Zoology, Vancouver, BC, Canada
| | - Chunqi Ma
- University of British Columbia, Department of Psychology, Vancouver, BC, Canada
| | - Donna L Maney
- Emory University, Department of Psychology, Atlanta, GA, USA
| | - Kiran K Soma
- University of British Columbia, Department of Zoology, Vancouver, BC, Canada; University of British Columbia, Department of Psychology, Vancouver, BC, Canada; Djavad Mowafaghian Centre for Brain Health, Canada
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5
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Eaton J, Pradhan DS, Barske J, Fusani L, Canoine V, Schlinger BA. 3β-HSD expression in the CNS of a manakin and finch. Gen Comp Endocrinol 2018; 256:43-49. [PMID: 28935582 PMCID: PMC5742301 DOI: 10.1016/j.ygcen.2017.09.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 09/01/2017] [Accepted: 09/16/2017] [Indexed: 12/26/2022]
Abstract
The prohormone, dehydroepiandrosterone (DHEA) circulates in vertebrate blood with the potential for actions on target tissues including the central nervous system (CNS). Many actions of DHEA require its conversion into more active products, some of which are catalyzed by the enzyme 3β-hydroxysteroid-dehydrogenase/isomerase (3β-HSD). Studies of birds show both expression and activity of 3β-HSD in brain and its importance in regulating social behavior. In oscine songbirds, 3β-HSD is expressed at reasonably high levels in brain, possibly linked to their complex neural circuitry controlling song. Studies also indicate that circulating DHEA may serve as the substrate for neural 3β-HSD to produce active steroids that activate behavior during non-breeding seasons. In the golden-collared manakin (Manacus vitellinus), a sub-oscine bird, low levels of courtship behavior are displayed by males when circulating testosterone levels are basal. Therefore, we asked whether DHEA circulates in blood of manakins and whether the brain expresses 3β-HSD mRNA. Given that the spinal cord is a target of androgens and likely important in regulating acrobatic movements, we also examined expression of this enzyme in the manakin spinal cord. For comparison, we examined expression levels with those of an oscine songbird, the zebra finch (Taeniopygia guttata), a species in which brain, but not spinal cord, 3β-HSD has been well studied. DHEA was detected in manakin blood at levels similar to that seen in other species. As described previously, 3β-HSD was expressed in all zebra finch brain regions examined. By contrast, expression of 3β-HSD was only detected in the manakin hypothalamus where levels were greater than zebra finches. In spinal cord, 3β-HSD was detected in some but not all regions in both species. These data point to species differences and indicate that manakins have the substrate and neural machinery to convert circulating DHEA into potentially active androgens and/or estrogens.
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Affiliation(s)
- Joy Eaton
- Department of Integrative Biology and Physiology, University of California, Los Angeles, United States
| | - Devaleena S Pradhan
- Department of Integrative Biology and Physiology, University of California, Los Angeles, United States; Laboratory for Neuroendocrinology, University of California, Los Angeles, United States.
| | - Julia Barske
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, United States
| | - Leonida Fusani
- Department of Cognitive Biology, University of Vienna, Austria; Konrad Lorenz Institute of Ethology, University of Veterinary Medicine, Vienna, Austria
| | - Virginie Canoine
- Department of Behavioural Biology, University of Vienna, Austria
| | - Barney A Schlinger
- Department of Integrative Biology and Physiology, University of California, Los Angeles, United States; Laboratory for Neuroendocrinology, University of California, Los Angeles, United States; Department of Ecology and Evolutionary Biology, University of California, Los Angeles, United States
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6
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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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7
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Rendon NM, Amez AC, Proffitt MR, Bauserman ER, Demas GE. Aggressive behaviours track transitions in seasonal phenotypes of female Siberian hamsters. Funct Ecol 2017; 31:1071-1081. [PMID: 28757672 PMCID: PMC5526640 DOI: 10.1111/1365-2435.12816] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Seasonally breeding animals exhibit profound physiological and behavioural responses to changes in ambient day length (photoperiod), including changes in reproductive function and territorial aggression.Species where aggression persists when gonads are regressed and circulating levels of gonadal hormones are low, such as Siberian hamsters (Phodopus sungorus) and song sparrows (Melospiza melodia), challenge the well-established framework that gonadal hormones are important mediators of aggression.A solution to this apparent paradox is that a season-specific increase in sensitivity to hormones in brain areas associated with aggression offsets low levels of gonadal hormones during periods of reproductive quiescence.To test this hypothesis, we manipulated photoperiod to induce natural fluctuations in seasonal phenotype across multiple stages of the annual reproductive cycle in female Siberian hamsters that display increased aggression during short-day reproductive quiescence, suggesting that behaviour persists independent of gonadal steroids.Females were housed in long "summer" days or short "winter" days for 10, 24 or 30 weeks to capture gonadal regression, transition back to a reproductively functional state and full gonadal recrudescence, respectively.Long-day animals maintained reproductive functionality and displayed low aggression across all time points. By week 10, short-day reproductively responsive females underwent gonadal regression and displayed increased aggression; non-responsive animals showed no such changes. At week 24, animals were in a transitional period and displayed an intermediate phenotype with respect to reproduction and aggression. By week 30, short-day females were fully recrudesced and returned to long-day-like levels of aggression.Consistent with our hypothesis, gonadally regressed females displayed decreases in 17β-oestradiol (oestradiol) levels, but site-specific increases in the abundance of brain oestrogen receptor-alpha (ERα) in regions associated with aggression, but not reproduction. Increased site-specific ERα may function as a compensatory mechanism to allow increased responsiveness to oestradiol in regulating aggression in lieu of high circulating concentrations of hormones.Collectively, these results broaden our understanding of how breeding phenology maps onto social behaviour and the mechanisms that have evolved to coordinate behaviours that occur in non-breeding contexts.
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Affiliation(s)
- Nikki M Rendon
- Department of Biology, Center for the Integrative Study of Animal Behavior, Program in Neuroscience, Indiana University, Bloomington, IN 47405, USA
| | - Andrea C Amez
- Department of Biology, Center for the Integrative Study of Animal Behavior, Program in Neuroscience, Indiana University, Bloomington, IN 47405, USA
| | - Melissa R Proffitt
- Department of Biology, Center for the Integrative Study of Animal Behavior, Program in Neuroscience, Indiana University, Bloomington, IN 47405, USA
| | - Elizabeth R Bauserman
- Department of Biology, Center for the Integrative Study of Animal Behavior, Program in Neuroscience, Indiana University, Bloomington, IN 47405, USA
| | - Gregory E Demas
- Department of Biology, Center for the Integrative Study of Animal Behavior, Program in Neuroscience, Indiana University, Bloomington, IN 47405, USA
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8
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Rendon NM, Demas GE. Bi‐directional actions of dehydroepiandrosterone and aggression in female Siberian hamsters. ACTA ACUST UNITED AC 2015; 325:116-21. [DOI: 10.1002/jez.2001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 12/03/2015] [Accepted: 12/03/2015] [Indexed: 11/06/2022]
Affiliation(s)
- Nikki M. Rendon
- Department of BiologyCenter for the Integrative Study of Animal BehaviorProgram in NeuroscienceIndiana UniversityBloomingtonIndiana
| | - Gregory E. Demas
- Department of BiologyCenter for the Integrative Study of Animal BehaviorProgram in NeuroscienceIndiana UniversityBloomingtonIndiana
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9
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Sex steroid profiles and pair-maintenance behavior of captive wild-caught zebra finches (Taeniopygia guttata). J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2015; 202:35-44. [PMID: 26610331 DOI: 10.1007/s00359-015-1050-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Revised: 10/12/2015] [Accepted: 10/29/2015] [Indexed: 12/19/2022]
Abstract
Here, we studied the life-long monogamous zebra finch, to examine the relationship between circulating sex steroid profiles and pair-maintenance behavior in pairs of wild-caught zebra finches (paired in the laboratory for >1 month). We used liquid chromatography-tandem mass spectrometry to examine a total of eight androgens and progestins [pregnenolone, progesterone, dehydroepiandrosterone (DHEA), androstenediol, pregnan-3,17-diol-20-one, androsterone, androstanediol, and testosterone]. In the plasma, only pregnenolone, progesterone, DHEA, and testosterone were above the limit of quantification. Sex steroid profiles were similar between males and females, with only circulating progesterone levels significantly different between the sexes (female > male). Circulating pregnenolone levels were high in both sexes, suggesting that pregnenolone might serve as a circulating prohormone for local steroid synthesis in zebra finches. Furthermore, circulating testosterone levels were extremely low in both sexes. Additionally, we found no correlations between circulating steroid levels and pair-maintenance behavior. Taken together, our data raise several interesting questions about the neuroendocrinology of zebra finches.
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10
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Krentzel AA, Remage-Healey L. Sex differences and rapid estrogen signaling: A look at songbird audition. Front Neuroendocrinol 2015; 38:37-49. [PMID: 25637753 PMCID: PMC4484764 DOI: 10.1016/j.yfrne.2015.01.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 01/13/2015] [Accepted: 01/17/2015] [Indexed: 02/07/2023]
Abstract
The actions of estrogens have been associated with brain differentiation and sexual dimorphism in a wide range of vertebrates. Here we consider the actions of brain-derived 'neuroestrogens' in the forebrain and the accompanying differences and similarities observed between males and females in a variety of species. We summarize recent evidence showing that baseline and fluctuating levels of neuroestrogens within the auditory forebrain of male and female zebra finches are largely similar, and that neuroestrogens enhance auditory representations in both sexes. With a comparative perspective we review evidence that non-genomic mechanisms of neuroestrogen actions are sexually differentiated, and we propose a working model for nonclassical estrogen signaling via the MAPK intracellular signaling cascade in the songbird auditory forebrain that is informed by the way sex differences may be compensated. This view may lead to a more comprehensive understanding of how sex influences estradiol-dependent modulation of sensorimotor representations.
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Affiliation(s)
- Amanda A Krentzel
- Neuroscience and Behavior Program, Center for Neuroendocrine Studies, Department of Psychological and Brain Sciences, University of Massachusetts Amherst, Amherst, MA 01003, United States
| | - Luke Remage-Healey
- Neuroscience and Behavior Program, Center for Neuroendocrine Studies, Department of Psychological and Brain Sciences, University of Massachusetts Amherst, Amherst, MA 01003, United States.
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11
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Rouse ML, Stevenson TJ, Fortune ES, Ball GF. Reproductive state modulates testosterone-induced singing in adult female European starlings (Sturnus vulgaris). Horm Behav 2015; 72:78-87. [PMID: 25989596 PMCID: PMC4469036 DOI: 10.1016/j.yhbeh.2015.04.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 04/27/2015] [Accepted: 04/29/2015] [Indexed: 01/13/2023]
Abstract
European starlings (Sturnus vulgaris) exhibit seasonal changes in singing and in the volumes of the neural substrate. Increases in song nuclei volume are mediated at least in part by increases in day length, which is also associated with increases in plasma testosterone (T), reproductive activity, and singing behavior in males. The correlations between photoperiod (i.e. daylength), T, reproductive state and singing hamper our ability to disentangle causal relationships. We investigated how photoperiodic-induced variation in reproductive state modulates the effects of T on singing behavior and song nuclei volumes in adult female starlings. Female starlings do not naturally produce measureable levels of circulating T but nevertheless respond to exogenous T, which induces male-like singing. We manipulated photoperiod by placing birds in a photosensitive or photorefractory state and then treated them with T-filled or empty silastic implants. We recorded morning singing behavior for 3 weeks, after which we assessed reproductive condition and measured song nuclei volumes. We found that T-treated photosensitive birds sang significantly more than all other groups including T-treated photorefractory birds. All T-treated birds had larger song nuclei volumes than with blank-treated birds (despite photorefractory T-treated birds not increasing song-rate). There was no effect of photoperiod on the song nuclei volumes of T-treated birds. These data show that the behavioral effects of exogenous T can be modulated by reproductive state in adult female songbirds. Furthermore, these data are consistent with other observations that increases in singing rate in response to T are not necessarily due to the direct effects of T on song nuclei volume.
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Affiliation(s)
- Melvin L Rouse
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA.
| | - Tyler J Stevenson
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - Eric S Fortune
- Department of Biological Sciences, New Jersey Institute of Technology, University Heights, Newark, NJ, USA
| | - Gregory F Ball
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA
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12
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Heimovics SA, Trainor BC, Soma KK. Rapid Effects of Estradiol on Aggression in Birds and Mice: The Fast and the Furious. Integr Comp Biol 2015; 55:281-93. [PMID: 25980562 DOI: 10.1093/icb/icv048] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Across invertebrates and vertebrates, steroids are potent signaling molecules that affect nearly every cell in the organism, including cells of the nervous system. Historically, researchers have focused on the genomic (or "nuclear-initiated") effects of steroids. However, all classes of steroids also have rapid non-genomic (or "membrane-initiated") effects, although there is far less basic knowledge of these non-genomic effects. In particular, steroids synthesized in the brain ("neurosteroids") have genomic and non-genomic effects on behavior. Here, we review evidence that estradiol has rapid effects on aggression, an important social behavior, and on intracellular signaling cascades in relevant regions of the brain. In particular, we focus on studies of song sparrows (Melospiza melodia) and Peromyscus mice, in which estradiol has rapid behavioral effects under short photoperiods only. Furthermore, in captive Peromyscus, estrogenic compounds (THF-diols) in corncob bedding profoundly alter the rapid effects of estradiol. Environmental factors in the laboratory, such as photoperiod, diet, and bedding, are critical variables to consider in experimental design. These studies are consistent with the hypothesis that locally-produced steroids are more likely than systemic steroids to act via non-genomic mechanisms. Furthermore, these studies illustrate the dynamic balance between genomic and non-genomic signaling for estradiol, which is likely to be relevant for other steroids, behaviors, and species.
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Affiliation(s)
- Sarah A Heimovics
- *Department of Biology, University of St Thomas, St Paul, MN 55105, USA;
| | - Brian C Trainor
- Department of Psychology, University of California-Davis, Davis, CA 95616, USA
| | - Kiran K Soma
- Departments of Psychology and Zoology, Graduate Program in Neuroscience, University of British Columbia, Vancouver, British Columbia, V6T 1Z7, Canada
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13
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Tsutsui K, Haraguchi S, Inoue K, Miyabara H, Ubuka T, Hatori M, Hirota T, Fukada Y. New biosynthesis and biological actions of avian neurosteroids. J Exp Neurosci 2013; 7:15-29. [PMID: 25157204 PMCID: PMC4089810 DOI: 10.4137/jen.s11148] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
De novo neurosteroidogenesis from cholesterol occurs in the brain of various avian species. However, the biosynthetic pathways leading to the formation of neurosteroids are still not completely elucidated. We have recently found that the avian brain produces 7α-hydroxypregnenolone, a novel bioactive neurosteroid that stimulates locomotor activity. Until recently, it was believed that neurosteroids are produced in neurons and glial cells in the central and peripheral nervous systems. However, our recent studies on birds have demonstrated that the pineal gland, an endocrine organ located close to the brain, is an important site of production of neurosteroids de novo from cholesterol. 7α-Hydroxypregnenolone is a major pineal neurosteroid that stimulates locomotor activity of juvenile birds, connecting light-induced gene expression with locomotion. The other major pineal neurosteroid allopregnanolone is involved in Purkinje cell survival during development. This paper highlights new aspects of neurosteroid synthesis and actions in birds.
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Affiliation(s)
- Kazuyoshi Tsutsui
- Laboratory of Integrative Brain Sciences, Department of Biology and Center for Medical Life Science, Waseda University, Tokyo, Japan
| | - Shogo Haraguchi
- Laboratory of Integrative Brain Sciences, Department of Biology and Center for Medical Life Science, Waseda University, Tokyo, Japan
| | - Kazuhiko Inoue
- Laboratory of Integrative Brain Sciences, Department of Biology and Center for Medical Life Science, Waseda University, Tokyo, Japan
| | - Hitomi Miyabara
- Laboratory of Integrative Brain Sciences, Department of Biology and Center for Medical Life Science, Waseda University, Tokyo, Japan
| | - Takayoshi Ubuka
- Laboratory of Integrative Brain Sciences, Department of Biology and Center for Medical Life Science, Waseda University, Tokyo, Japan
| | - Megumi Hatori
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Tsuyoshi Hirota
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Yoshitaka Fukada
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Tokyo, Japan
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Tsutsui K, Haraguchi S, Hatori M, Hirota T, Fukada Y. Biosynthesis and biological actions of pineal neurosteroids in domestic birds. Neuroendocrinology 2013; 98:97-105. [PMID: 23797037 DOI: 10.1159/000353782] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Accepted: 06/15/2013] [Indexed: 11/19/2022]
Abstract
The central and peripheral nervous systems have the capacity of synthesizing steroids de novo from cholesterol, the so-called 'neurosteroids'. De novo synthesis of neurosteroids from cholesterol appears to be a conserved property across the subphylum vertebrata. Until recently, it was generally believed that neurosteroids are produced in neurons and glial cells in the central and peripheral nervous systems. However, our recent studies on birds have demonstrated that the pineal gland, an endocrine organ located close to the brain, is an important site of production of neurosteroids de novo from cholesterol. 7α-Hydroxypregnenolone is a major pineal neurosteroid that stimulates locomotor activity of juvenile birds, connecting light-induced gene expression with locomotion. The other major pineal neurosteroid allopregnanolone is involved in Purkinje cell survival by suppressing the activity of caspase-3, a crucial mediator of apoptosis during cerebellar development. This review is an updated summary of the biosynthesis and biological actions of pineal neurosteroids.
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Affiliation(s)
- Kazuyoshi Tsutsui
- Department of Biology and Center for Medical Life Science, Waseda University, Tokyo, Japan
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15
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Abstract
The long-held dogma that the brain is a target of steroids produced by peripheral organs has delayed the widespread acceptance of the functional importance of neurosteroidogenesis. Comparative studies have been vital for establishing the key actions of gonadal and adrenal hormones on brain and behaviour. No doubt, studies across diverse phyla will continue to be crucial for revealing the true significance of neurosteroidogenesis to proper function of the vertebrate brain. Here, we review work carried out in our laboratory, as well as in others, highlighting advances to our understanding of brain steroid synthesis and action using songbirds as animal models. These studies show that steroidogenic transporters and enzymes are present in the songbird brain and that their expression and/or activities are subject to developmental, seasonal or short-term regulation. Our work in a songbird points to synaptic synthesis of neuroactive steroids and fast, perisynaptic membrane actions. Combined with evidence for rapid steroidal control of behaviour, these studies firmly establish a neuromodulatory role for avian neurosteroids. We hope this work will join with that of other species to embolden the acceptance of neurosteroidal signalling as a core property of vertebrate neurobiology.
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Affiliation(s)
- B A Schlinger
- Laboratory of Neuroendocrinology, Department of Integrative Biology and Physiology, Brain Research Institute, UCLA, Los Angeles, CA 90095, USA.
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16
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Taves MD, Ma C, Heimovics SA, Saldanha CJ, Soma KK. Measurement of steroid concentrations in brain tissue: methodological considerations. Front Endocrinol (Lausanne) 2011; 2:39. [PMID: 22654806 PMCID: PMC3356067 DOI: 10.3389/fendo.2011.00039] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2011] [Accepted: 09/06/2011] [Indexed: 12/17/2022] Open
Abstract
It is well recognized that steroids are synthesized de novo in the brain (neurosteroids). In addition, steroids circulating in the blood enter the brain. Steroids play numerous roles in the brain, such as influencing neural development, adult neuroplasticity, behavior, neuroinflammation, and neurodegenerative diseases such as Alzheimer's disease. In order to understand the regulation and functions of steroids in the brain, it is important to directly measure steroid concentrations in brain tissue. In this brief review, we discuss methods for the detection and quantification of steroids in the brain. We concisely present the major advantages and disadvantages of different technical approaches at various experimental stages: euthanasia, tissue collection, steroid extraction, steroid separation, and steroid measurement. We discuss, among other topics, the potential effects of anesthesia and saline perfusion prior to tissue collection; microdissection via Palkovits punch; solid phase extraction; chromatographic separation of steroids; and immunoassays and mass spectrometry for steroid quantification, particularly the use of mass spectrometry for "steroid profiling." Finally, we discuss the interpretation of local steroid concentrations, such as comparing steroid levels in brain tissue with those in the circulation (plasma vs. whole blood samples; total vs. free steroid levels). We also present reference values for a variety of steroids in different brain regions of adult rats. This brief review highlights some of the major methodological considerations at multiple experimental stages and provides a broad framework for designing studies that examine local steroid levels in the brain as well as other steroidogenic tissues, such as thymus, breast, and prostate.
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Affiliation(s)
- Matthew D. Taves
- Department of Psychology, University of British ColumbiaVancouver, BC, Canada
- Department of Zoology, University of British ColumbiaVancouver, BC, Canada
- *Correspondence: Matthew D. Taves, Department of Psychology, University of British Columbia, 2136 West Mall, Vancouver, BC, Canada V6T 1Z4. e-mail:
| | - Chunqi Ma
- Department of Psychology, University of British ColumbiaVancouver, BC, Canada
| | - Sarah A. Heimovics
- Department of Psychology, University of British ColumbiaVancouver, BC, Canada
| | - Colin J. Saldanha
- Department of Biological Sciences, Lehigh UniversityBethlehem, PA, USA
- Program in Cognitive Science, Lehigh UniversityBethlehem, PA, USA
| | - Kiran K. Soma
- Department of Psychology, University of British ColumbiaVancouver, BC, Canada
- Department of Zoology, University of British ColumbiaVancouver, BC, Canada
- Graduate Program in Neuroscience, University of British ColumbiaVancouver, BC, Canada
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17
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Tsutsui K. Neurosteroid biosynthesis and function in the brain of domestic birds. Front Endocrinol (Lausanne) 2011; 2:37. [PMID: 22645509 PMCID: PMC3355851 DOI: 10.3389/fendo.2011.00037] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2011] [Accepted: 09/05/2011] [Indexed: 11/17/2022] Open
Abstract
It is now established that the brain and other nervous systems have the capability of forming steroids de novo, the so-called "neurosteroids." The pioneering discovery of Baulieu and his colleagues, using rodents, has opened the door to a new research field of "neurosteroids." In contrast to mammalian vertebrates, little has been known regarding de novo neurosteroidogenesis in the brain of birds. We therefore investigated neurosteroid formation and metabolism in the brain of quail, a domestic bird. Our studies over the past two decades demonstrated that the quail brain possesses cytochrome P450 side-chain cleavage enzyme (P450scc), 3β-hydroxysteroid dehydrogenase/Δ(5)-Δ(4)-isomerase (3β-HSD), 5β-reductase, cytochrome P450 17α-hydroxylase/c17,20-lyase (P450(17α,lyase)), 17β-HSD, etc., and produces pregnenolone, progesterone, 5β-dihydroprogesterone (5β-DHP), 3β, 5β-tetrahydroprogesterone (3β, 5β-THP), androstenedione, testosterone, and estradiol from cholesterol. Independently, Schlinger's laboratory demonstrated that the brain of zebra finch, a songbird, also produces various neurosteroids. Thus, the formation and metabolism of neurosteroids from cholesterol is now known to occur in the brain of birds. In addition, we recently found that the quail brain expresses cytochrome P450(7α) and produces 7α- and 7β-hydroxypregnenolone, previously undescribed avian neurosteroids, from pregnenolone. This paper summarizes the advances made in our understanding of neurosteroid formation and metabolism in the brain of domestic birds. This paper also describes what are currently known about physiological changes in neurosteroid formation and biological functions of neurosteroids in the brain of domestic and other birds.
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Affiliation(s)
- Kazuyoshi Tsutsui
- Laboratory of Integrative Brain Sciences, Department of Biology, Waseda University, and Center for Medical Life Science of Waseda UniversityShinjuku-ku, Tokyo, Japan
- *Correspondence: Kazuyoshi Tsutsui, Laboratory of Integrative Brain Sciences, Department of Biology, Waseda University, and Center for Medical Life Science of Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan. e-mail:
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18
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Taves MD, Schmidt KL, Ruhr IM, Kapusta K, Prior NH, Soma KK. Steroid concentrations in plasma, whole blood and brain: effects of saline perfusion to remove blood contamination from brain. PLoS One 2010; 5:e15727. [PMID: 21206751 PMCID: PMC3012083 DOI: 10.1371/journal.pone.0015727] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2010] [Accepted: 11/21/2010] [Indexed: 12/19/2022] Open
Abstract
The brain and other organs locally synthesize steroids. Local synthesis is suggested when steroid levels are higher in tissue than in the circulation. However, measurement of both circulating and tissue steroid levels are subject to methodological considerations. For example, plasma samples are commonly used to estimate circulating steroid levels in whole blood, but steroid levels in plasma and whole blood could differ. In addition, tissue steroid measurements might be affected by blood contamination, which can be addressed experimentally by using saline perfusion to remove blood. In Study 1, we measured corticosterone and testosterone (T) levels in zebra finch (Taeniopygia guttata) plasma, whole blood, and red blood cells (RBC). We also compared corticosterone in plasma, whole blood, and RBC at baseline and after 60 min restraint stress. In Study 2, we quantified corticosterone, dehydroepiandrosterone (DHEA), T, and 17β-estradiol (E2) levels in the brains of sham-perfused or saline-perfused subjects. In Study 1, corticosterone and T concentrations were highest in plasma, significantly lower in whole blood, and lowest in RBC. In Study 2, saline perfusion unexpectedly increased corticosterone levels in the rostral telencephalon but not other regions. In contrast, saline perfusion decreased DHEA levels in caudal telencephalon and diencephalon. Saline perfusion also increased E2 levels in caudal telencephalon. In summary, when comparing local and systemic steroid levels, the inclusion of whole blood samples should prove useful. Moreover, blood contamination has little or no effect on measurement of brain steroid levels, suggesting that saline perfusion is not necessary prior to brain collection. Indeed, saline perfusion itself may elevate and lower steroid concentrations in a rapid, region-specific manner.
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Affiliation(s)
- Matthew D Taves
- Department of Psychology, University of British Columbia, Vancouver, Canada.
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19
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Pradhan DS, Newman AEM, Wacker DW, Wingfield JC, Schlinger BA, Soma KK. Aggressive interactions rapidly increase androgen synthesis in the brain during the non-breeding season. Horm Behav 2010; 57:381-9. [PMID: 20116379 PMCID: PMC2849911 DOI: 10.1016/j.yhbeh.2010.01.008] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2009] [Revised: 12/30/2009] [Accepted: 01/14/2010] [Indexed: 12/15/2022]
Abstract
In male song sparrows (Melospiza melodia), territorial challenges during the breeding season can rapidly increase circulating levels of testosterone (T). During the non-breeding season, male song sparrows are highly aggressive, but the gonads are regressed and plasma T levels are non-detectable and unaffected by territorial challenges. The pro-hormone dehydroepiandrosterone (DHEA) is elevated in song sparrow plasma and brain during the non-breeding season and may be locally converted to sex steroids in the brain to regulate aggression. The enzyme 3beta-hydroxysteroid dehydrogenase/Delta5-Delta4 isomerase (3beta-HSD) converts DHEA to androstenedione (AE) using the cofactor NAD(+), and this is a critical rate-limiting step. We predicted that brain 3beta-HSD activity varies seasonally and is rapidly modulated by aggressive challenges. In the first study, brain 3beta-HSD activity was highest in the non-breeding season in specific regions. In the second study, a simulated territorial challenge rapidly increased aggressive behavior in non-breeding song sparrows. Brain 3beta-HSD activity, when measured without exogenous NAD(+), increased by approximately 250 to 500% in telencephalic regions of challenged subjects. When brain 3beta-HSD activity was measured with exogenous NAD(+), these effects of territorial challenges were not observed. These data suggest that territorial challenges rapidly increase endogenous NAD(+) levels or increase 3beta-HSD activity specifically within a NAD-rich subcellular compartment. Together, these two studies suggest a shift from systemic to local sex steroid signaling in the non-breeding season. Local steroid signaling produces high spatial and temporal specificity of steroid signals and avoids the costs of high systemic T levels during the non-breeding season.
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Affiliation(s)
- Devaleena S Pradhan
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4.
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20
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Charlier TD, Cornil CA, Ball GF, Balthazart J. Diversity of mechanisms involved in aromatase regulation and estrogen action in the brain. Biochim Biophys Acta Gen Subj 2010; 1800:1094-105. [PMID: 20060879 DOI: 10.1016/j.bbagen.2009.12.010] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Revised: 12/10/2009] [Accepted: 12/31/2009] [Indexed: 12/19/2022]
Abstract
BACKGROUND The mechanisms through which estrogens modulate neuronal physiology, brain morphology, and behavior in recent years have proven to be far more complex than previously thought. For example, a second nuclear estrogen receptor has been identified, a new family of coregulatory proteins regulating steroid-dependent gene transcriptions was discovered and, finally, it has become clear that estrogens have surprisingly rapid effects based on their actions on cell membranes, which in turn result in the modulation of intracellular signaling cascades. SCOPE OF REVIEW This paper presents a selective review of new findings in this area related to work in our laboratories, focusing on the role of estrogens in the activation of male sexual behavior. Two separate topics are considered. We first discuss functions of the steroid receptor coactivator-1 (SRC-1) that has emerged as a key limiting factor for behavioral effects of estradiol. Knocking-down its expression by antisense oligonucleotides drastically inhibits male-typical sexual behaviors. Secondly, we describe rapid regulations of brain estradiol production by calcium-dependent phosphorylations of the aromatase enzyme, themselves under the control of neurotransmitter activity. MAJOR CONCLUSIONS These rapid changes in estrogen bioavailability have clear behavioral consequences. Increases or decreases in estradiol concentrations respectively obtained by an acute injection of estradiol itself or of an aromatase inhibitor lead within 15-30 min to parallel changes in sexual behavior frequencies. GENERAL SIGNIFICANCE These new controls of estrogen action offer a vast array of possibilities for discrete local controls of estrogen action. They also represent a formidable challenge for neuroendocrinologists trying to obtain an integrated view of brain function in relation to behavior.
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London SE, Remage-Healey L, Schlinger BA. Neurosteroid production in the songbird brain: a re-evaluation of core principles. Front Neuroendocrinol 2009; 30:302-14. [PMID: 19442685 PMCID: PMC2724309 DOI: 10.1016/j.yfrne.2009.05.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Revised: 05/01/2009] [Accepted: 05/04/2009] [Indexed: 11/17/2022]
Abstract
Concepts of brain-steroid signaling have traditionally placed emphasis on the gonads and adrenals as the source of steroids, the strict dichotomy of early developmental ("organizational") and mature ("activational") effects, and a relatively slow mechanism of signaling through intranuclear receptors. Continuing research shows that these concepts are not inaccurate, but they are certainly incomplete. In this review, we focus on the song control circuit of songbird species to demonstrate how each of these concepts is limited. We discuss the solid evidence for steroid synthesis within the brain ("neurosteroidogenesis"), the role of neurosteroids in organizational events that occur both early in development and later in life, and how neurosteroids can act in acute and non-traditional ways. The songbird model therefore illustrates how neurosteroids can dramatically increase the diversity of steroid-sensitive brain functions in a behaviorally-relevant system. We hope this inspires further research and thought into neurosteroid signaling in songbirds and other animals.
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Affiliation(s)
- Sarah E. London
- Institute for Genomic Biology, University of Illinois, Urbana-Champaign, Urbana, IL 61801
| | - Luke Remage-Healey
- Department of Physiological Science &, Ecology and Evolutionary Biology, Brain Research Institute, University of California, Los Angeles, Los Angeles, California 90095
| | - Barney A. Schlinger
- Department of Physiological Science &, Ecology and Evolutionary Biology, Brain Research Institute, University of California, Los Angeles, Los Angeles, California 90095
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22
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Remage-Healey L, London SE, Schlinger BA. Birdsong and the neural production of steroids. J Chem Neuroanat 2009; 39:72-81. [PMID: 19589382 DOI: 10.1016/j.jchemneu.2009.06.009] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2009] [Revised: 05/30/2009] [Accepted: 06/25/2009] [Indexed: 10/20/2022]
Abstract
The forebrain circuits involved in singing and audition (the 'song system') in songbirds exhibit a remarkable capacity to synthesize and respond to steroid hormones. This review considers how local brain steroid production impacts the development, sexual differentiation, and activity of song system circuitry. The songbird forebrain contains all of the enzymes necessary for the de novo synthesis of steroids - including neuroestrogens - from cholesterol. Steroid production enzymes are found in neuronal cell bodies, but they are also expressed in pre-synaptic terminals in the song system, indicating a novel mode of brain steroid delivery to local circuits. The song system expresses nuclear hormone receptors, consistent with local action of brain-derived steroids. Local steroid production also occurs in brain regions that do not express nuclear hormone receptors, suggesting a non-classical mode of action. Recent evidence indicates that local steroid levels can change rapidly within the forebrain, in a manner similar to traditional neuromodulators. Lastly, we consider growing evidence for modulatory interactions between brain-derived steroids and neurotransmitter/neuropeptide networks within the song system. Songbirds have therefore emerged as a rich and powerful model system to explore the neural and neurochemical regulation of social behavior.
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Affiliation(s)
- Luke Remage-Healey
- Department of Physiological Science & Ecology and Evolutionary Biology, Brain Research Institute, University of California, Los Angeles, CA 90095, United States
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Newman AEM, Soma KK. Corticosterone and dehydroepiandrosterone in songbird plasma and brain: effects of season and acute stress. Eur J Neurosci 2009; 29:1905-14. [PMID: 19473242 DOI: 10.1111/j.1460-9568.2009.06748.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Prolonged increases in plasma glucocorticoids can exacerbate neurodegeneration. In rats, these neurodegenerative effects can be reduced by dehydroepiandrosterone (DHEA), an androgen precursor with anti-glucocorticoid actions. In song sparrows, season and acute restraint stress affect circulating levels of corticosterone and DHEA, and the effects of stress differ in plasma collected from the brachial and jugular veins. Jugular plasma is an indirect index of the neural steroidal milieu. Here, we directly measured corticosterone and DHEA in several brain regions and jugular plasma, and examined the effects of season and acute restraint stress (30 min) (n = 571 samples). Corticosterone levels were up to 10x lower in brain than in jugular plasma. In contrast, DHEA levels were up to 5x higher in brain than in jugular plasma and were highest in the hippocampus. Corticosterone and DHEA concentrations were strongly seasonally regulated in plasma but, surprisingly, not seasonally regulated in brain. Acute stress increased corticosterone levels in plasma and brain, except during the molt, when stress unexpectedly decreased corticosterone levels in the hippocampus. Acute stress increased DHEA levels in plasma during the molt but had no effects on DHEA levels in brain. This is the first study to measure (i) corticosterone or DHEA levels in the brain of adult songbirds and (ii) seasonal changes in corticosterone or DHEA levels in the brain of any species. These results highlight several critical differences between systemic and local steroid concentrations and the difficulty of using circulating steroid levels to infer local steroid levels within the brain.
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Affiliation(s)
- Amy E M Newman
- Department of Psychology, University of British Columbia, Vancouver, BC, Canada.
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Abstract
The enzyme aromatase, which converts androgens into oestrogens, is expressed throughout the brain in zebra finches. Aromatase is enzymatically active in both cell bodies and synaptic terminals of neurones of the songbird brain, particularly within the forebrain motor and auditory networks. Aromatisation within synaptic terminals could thus provide localised and acute modulatory oestrogens within the forebrain during singing and/or audition. In male zebra finches, we tested the hypothesis that forebrain aromatase activity is elevated during singing behaviour and/or hearing male song. The present study reports that aromatase activity is elevated in males that were singing for 30 min compared to nonsinging males, and that this elevation occurs only within the cellular compartment that contains synaptic terminals. In a separate experiment, males that heard acoustic playback of song for 30 min exhibited no differences in aromatase activity or in aromatase mRNA levels, as revealed by quantitative polymerase chain reaction analysis. Therefore, these results indicate that activation of the motor pathway for song production is linked to local elevations in synaptic aromatase activity within the forebrain of male zebra finches. Future experiments could assess whether elevated synaptic aromatase activity during song is dependent on acute regulation of the aromatase protein.
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Affiliation(s)
- L Remage-Healey
- Department of Physiological Science, Laboratory for Neuroendocrinology, Brain Research Institute, University of California, Los Angeles, CA 90095, USA.
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25
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Newman AEM, Pradhan DS, Soma KK. Dehydroepiandrosterone and corticosterone are regulated by season and acute stress in a wild songbird: jugular versus brachial plasma. Endocrinology 2008; 149:2537-45. [PMID: 18276756 PMCID: PMC2878327 DOI: 10.1210/en.2007-1363] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Stress has well-known effects on adrenal glucocorticoid secretion, and chronic elevation of glucocorticoids can have detrimental effects on the brain. Dehydroepiandrosterone (DHEA), an androgen precursor synthesized in the adrenal glands or the brain itself, has anti-glucocorticoid properties, but little is known about the role of DHEA in the stress response, particularly in the brain. Here, we measured the effects of acute restraint on circulating corticosterone (CORT) and DHEA levels in wild song sparrows. Blood was collected from either the brachial or jugular vein. In songbirds, jugular plasma is enriched with neurally synthesized steroids, and therefore, jugular plasma is an indirect index of the neural steroidal milieu. Subjects were sampled during four times of year: breeding, molt, early nonbreeding, and mid-nonbreeding. Baseline CORT and DHEA levels showed similar seasonal changes; both steroids were elevated during the breeding season. Baseline CORT and DHEA levels were similar in jugular and brachial plasma. Acute stress had robust effects on CORT and DHEA that were season specific and vein specific. For CORT, during the molt, stress increased jugular CORT more than brachial CORT. For DHEA, during the breeding season, stress decreased jugular DHEA but not brachial DHEA. During the molt, stress increased jugular DHEA but not brachial DHEA. Acute stress did not affect brachial DHEA. These data suggest that acute stress specifically affects the balance between DHEA synthesis and metabolism in the brain. Furthermore, these results suggest that CORT and DHEA are locally synthesized in the brain during molt, when systemic levels of CORT and DHEA are low.
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Affiliation(s)
- Amy E M Newman
- Department of Psychology, University of British Columbia, 2136 West Mall, Vancouver, British Columbia, Canada V6T 1Z4.
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