Bi‐directional actions of dehydroepiandrosterone and aggression in female Siberian hamsters

Rendon, Nikki M.; Demas, Gregory E.

doi:10.1002/jez.2001

Cited by 22 publications

(20 citation statements)

References 26 publications

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“…By contrast, SD‐NR and Mel‐M females exhibited no significant changes in circulating DHEA and T, but showed aggression‐induced increases in circulating E 2 . These findings support our previous work, in which we found that SD hamsters display aggression‐induced decreases in circulating DHEA and T 40,53,68 and that timed melatonin injections cause decreases in circulating DHEA and T in LD males after an aggressive encounter 40 . Other studies have shown that administering E 2 to male song sparrows ( M. melodia ), white‐throated sparrows ( Zonotrichia albicollis ), beach mice ( P. polionotus ) and California mice ( Peromyscus californicus ) increases aggressive behaviour during the non‐breeding season, 9,24,69‐71 whereas blocking aromatase in circulation decreases aggression in non‐breeding male song sparrows 72 .…”

Section: Discussionsupporting

confidence: 91%

“…Pre‐ and post‐aggression levels of serum DHEA, T and E 2 were quantified using commercially available enzyme immunoassay kits that have been previously validated in this species (DHEA: assay sensitivity = 0.108 ng mL ‐1 ; ALPCO Diagnostics, Salem, NH, USA; 20‐DHEHU‐E01 39,53 ; T: assay sensitivity = 5.67 pg mL ‐1 ; Assay Design, Ann Arbor, MI, USA; 900‐065 54,55 ; E 2 : assay sensitivity = 14.0 pg mL ‐1 ; Enzo Life Sciences, Farmingdale, NY, USA; ADI‐900‐174 25 ). Each of these kits is highly specific for the hormone of interest and have negligible or undetectable cross‐reactivity with other steroid hormones (DHEA kit: sulfated DHEA = 0.01%, T = 0.01%, E 2 = < 0.01%, cortisol = < 0.01%; T kit: 19‐hydroxytestosterone = 14.6%, androstenedione = 7.2%, DHEA = 0.7%, E 2 = 0.4%; E 2 kit: oestrone = 17.8%, oestriol = 0.9%, T = 0.01%, DHEA = < 0.001%).…”

Section: Methodsmentioning

confidence: 99%

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Seasonal patterns of melatonin alter aggressive phenotypes of female Siberian hamsters

Rendon

Petersen

Munley

et al. 2020

J Neuroendocrinology

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Many animal species exhibit year‐round aggression, a behaviour that allows individuals to compete for limited resources in their environment (eg, food and mates). Interestingly, this high degree of territoriality persists during the non‐breeding season, despite low levels of circulating gonadal steroids (ie, testosterone [T] and oestradiol [E2]). Our previous work suggests that the pineal hormone melatonin mediates a ‘seasonal switch’ from gonadal to adrenal regulation of aggression in Siberian hamsters (Phodopus sungorus); solitary, seasonally breeding mammals that display increased aggression during the short, ‘winter‐like’ days (SDs) of the non‐breeding season. To test the hypothesis that melatonin elevates non‐breeding aggression by increasing circulating and neural steroid metabolism, we housed female hamsters in long days (LDs) or SDs, administered them timed or mis‐timed melatonin injections (mimic or do not mimic a SD‐like signal, respectively), and measured aggression, circulating hormone profiles and aromatase (ARO) immunoreactivity in brain regions associated with aggressive or reproductive behaviours (paraventricular hypothalamic nucleus [PVN], periaqueductal gray [PAG] and ventral tegmental area [VTA]). Females that were responsive to SD photoperiods (SD‐R) and LD females given timed melatonin injections (Mel‐T) exhibited gonadal regression and reduced circulating E2, but increased aggression and circulating dehydroepiandrosterone (DHEA). Furthermore, aggressive challenges differentially altered circulating hormone profiles across seasonal phenotypes; reproductively inactive females (ie, SD‐R and Mel‐T females) reduced circulating DHEA and T, but increased E2 after an aggressive interaction, whereas reproductively active females (ie, LD females, SD non‐responder females and LD females given mis‐timed melatonin injections) solely increased circulating E2. Although no differences in neural ARO abundance were observed, LD and SD‐R females showed distinct associations between ARO cell density and aggressive behaviour in the PVN, PAG and VTA. Taken together, these results suggest that melatonin increases non‐breeding aggression by elevating circulating steroid metabolism after an aggressive encounter and by regulating behaviourally relevant neural circuits in a region‐specific manner.

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Section: Discussionsupporting

confidence: 91%

Section: Methodsmentioning

confidence: 99%

Seasonal patterns of melatonin alter aggressive phenotypes of female Siberian hamsters

Rendon

Petersen

Munley

et al. 2020

J Neuroendocrinology

Self Cite

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“…Instead, adrenal hormones have been proposed to regulate aggression in SD-housed Siberian hamsters [37–39] and several other seasonal species [40]. It is likely that the conflicting findings in the present study, which indicated that testicular hormones increase aggression, are due to the type of aggression examined.…”

Section: Discussionmentioning

confidence: 59%

Dissociation of Puberty and Adolescent Social Development in a Seasonally Breeding Species

et al. 2018

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Alongside the development of sexual characteristics and reproductive competence, adolescents undergo marked cognitive, social, and emotional development [1]. A fundamental question is whether these changes are triggered by activation of the hypothalamic-pituitary-gonadal (HPG) axis at puberty (puberty dependent) or whether they occur independently of HPG activation (puberty independent). Disentangling puberty-dependent from puberty-independent mechanisms is difficult because puberty and adolescence typically proceed concurrently. Here, we test a new approach that leverages natural adaptations of a seasonally breeding species to dissociate pubertal status from chronological age. Siberian hamsters (Phodopus sungorus) reared in a long, summer-like day length (LD) exhibit rapid pubertal development, whereas those reared in a short, winter-like day length (SD) delay puberty by several months to synchronize breeding with the following spring [2, 3]. We tested whether the SD-induced delay in puberty delays the peri-adolescent decline in juvenile social play and the rise in aggression that characterizes adolescent social development in many species [4-6] and compared the results to those obtained after prepubertal gonadectomy. Neither SD rearing nor prepubertal gonadectomy altered the age at which hamsters transitioned from play to aggression; SD-reared hamsters completed this transition prior to puberty. SD rearing and prepubertal gonadectomy, however, increased levels of play in male and female juveniles, implicating a previously unknown role for prepubertal gonadal hormones in juvenile social behavior. Levels of aggression were also impacted (decreased) in SD-reared and gonadectomized males. These data demonstrate that puberty-independent mechanisms regulate the timing of adolescent social development, while prepubertal and adult gonadal hormones modulate levels of age-appropriate social behaviors.

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“…, see also: Soma & Wingfield ; Demas, Soma & Albers ; Soma et al . ; Prough, Clark & Klinge ; Rendon & Demas ). DHEA can serve as a precursor to testosterone and oestradiol, therefore metabolic conversion makes it possible for relatively low levels of circulating hormones to have dynamic behavioural effects across seasons, as observed across numerous mammals and birds (Hau, Stoddard & Soma ; Soma et al .…”

Section: Discussionmentioning

confidence: 99%

Aggressive behaviours track transitions in seasonal phenotypes of female Siberian hamsters

et al. 2017

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SUMMARY 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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Bi‐directional actions of dehydroepiandrosterone and aggression in female Siberian hamsters

Cited by 22 publications

References 26 publications

Seasonal patterns of melatonin alter aggressive phenotypes of female Siberian hamsters

Seasonal patterns of melatonin alter aggressive phenotypes of female Siberian hamsters

Dissociation of Puberty and Adolescent Social Development in a Seasonally Breeding Species

Aggressive behaviours track transitions in seasonal phenotypes of female Siberian hamsters

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