title: DHEA effects on brain and behavior: insights from comparative studies of aggression.
abstract: Historically, research on the neuroendocrinology of aggression has been dominated by the paradigm that the brain receives sex steroid hormones, such as testosterone (T), from the gonads, and then these gonadal hormones modulate behaviorally relevant neural circuits. While this paradigm has been extremely useful for advancing the field, recent studies reveal important alternatives. For example, most vertebrate species are seasonal breeders, and many species show aggression outside of the breeding season, when the gonads are regressed and circulating levels of gonadal steroids are relatively low. Studies in diverse avian and mammalian species suggest that adrenal dehydroepiandrosterone (DHEA), an androgen precursor and prohormone, is important for the expression of aggression when gonadal T synthesis is low. Circulating DHEA can be converted into active sex steroids within the brain. In addition, the brain can synthesize sex steroids de novo from cholesterol, thereby uncoupling brain steroid levels from circulating steroid levels. These alternative mechanisms to provide sex steroids to specific neural circuits may have evolved to avoid the costs of high circulating T levels during the non-breeding season. Physiological indicators of season (e.g., melatonin) may allow animals to switch from one neuroendocrine mechanism to another across the year. DHEA and neurosteroids are likely to be important for the control of multiple behaviors in many species, including humans. These studies yield fundamental insights into the regulation of DHEA secretion, the mechanisms by which DHEA affects behavior, and the brain regions and neural processes that are modulated by DHEA. It is clear that the brain is an important site of DHEA synthesis and action. This article is part of a Special Issue entitled 'Essential role of DHEA'.
authors.affiliation: Departments of Psychology and Zoology, Graduate Program in Neuroscience, and the Brain Research Centre, University of British Columbia, Vancouver, BC, Canada V6T 1Z4. Electronic address: ksoma@psych.ubc.ca.
authors.forename: Kiran K
authors.initials: KK
authors.lastname: Soma
authors.affiliation: Department of Biology, Program in Neuroscience, and Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, IN 47405, USA.
authors.forename: Nikki M
authors.initials: NM
authors.lastname: Rendon
authors.affiliation: Centre for Neurobiology of Stress, Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, Canada M1C 1A4.
authors.forename: Rudy
authors.initials: R
authors.lastname: Boonstra
authors.affiliation: Neuroscience Institute, and Center for Behavioral Neuroscience, Georgia State University, Atlanta, GA 30303, USA.
authors.forename: H Elliott
authors.initials: HE
authors.lastname: Albers
authors.affiliation: Department of Biology, Program in Neuroscience, and Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, IN 47405, USA.
authors.forename: Gregory E
authors.initials: GE
authors.lastname: Demas
mesh_terms: D000374:Aggression; D000728:Androgens / Q000378:metabolism; D000818:Animals; D001141:Aromatase / Q000378:metabolism; D001522:Behavior, Animal; D001921:Brain / Q000378:metabolism*; D006224:Cricetinae; D003687:Dehydroepiandrosterone / Q000378:metabolism*; D004958:Estradiol / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D011323:Primates; D051381:Rats; D012919:Social Behavior; D020308:Songbirds; D013739:Testosterone / Q000378:metabolism
chemical_list: D000728:Androgens; D013739:Testosterone; D003687:Dehydroepiandrosterone; D004958:Estradiol; D001141:Aromatase
keywords: Aggressive behavior; Aromatase; Estradiol; Hamster; Intracrinology; Sex difference; Songbird; Stress