Combined Aromatase Inhibitor and Antiandrogen Treatment Decreases Territorial Aggression in a Wild Songbird during the Nonbreeding Season

Soma, Kiran K.; Sullivan, Kim; Wingfield, John C.

doi:10.1006/gcen.1999.7334

Cited by 158 publications

(113 citation statements)

References 54 publications

Supporting

Mentioning

109

Contrasting

Order By: Relevance

“…In male Western song sparrows (Melospiza m. melodia), however, aggressive behavior during the nonbreeding season was reduced after blocking aromatase, the enzyme that converts T into E2. These experiments suggest that E2 might be involved in the regulation of nonbreeding aggression (Soma et al, 1999c. Differences in the regulatory mechanisms of aggressive behavior during the nonbreeding season might be due to different life styles, for example, migratory versus sedentary habits in different bird species.…”

Section: Introductionmentioning

confidence: 85%

“…In particular, several studies in mammals have shown that aggressive behavior is modulated by the activation of ER , but not ER (Ogawa et al, 1998;Scordalakes and Rissman, 2004). In Western song sparrows, E2 appears to be the main hormone regulating territorial aggression during the nonbreeding season (Soma et al, 1999c;Soma et al, 2000). Therefore, it is plausible that in spotted antbirds the increased expression of ER in POM during the nonbreeding season is related to an involvement of E2 in the control of aggressive behavior.…”

Section: Ar Era and Arom Expression In Pommentioning

confidence: 99%

See 1 more Smart Citation

Low sex steroids, high steroid receptors: Increasing the sensitivity of the nonreproductive brain

Canoine

Fusani

Schlinger

et al. 2006

Developmental Neurobiology

View full text Add to dashboard Cite

Male aggressive behavior is generally regulated by testosterone (T). In most temperate breeding males, aggressive behavior is only expressed during the reproductive period. At this time circulating T concentrations, brain steroid receptors, and steroid metabolic enzymes are elevated in many species relative to the nonreproductive period. Many tropical birds, however, display aggressive behavior both during the breeding and the nonbreeding season, but plasma levels of T can remain low throughout the year and show little seasonal fluctuation. Studies on the year-round territorial spotted antbird (Hylophylax n. naevioides) suggest that T nevertheless regulates aggressive behavior in both the breeding and nonbreeding season. We hypothesize that to regulate aggressive behaviors during the nonbreeding season, when T is at its minimum, male spotted antbirds increase brain sensitivity to steroids. This can be achieved by locally up-regulating androgen receptors (ARs), estrogen receptors (ERs), or the enzyme aromatase (AROM) that converts T into estradiol. We therefore compared mRNA expression of AR, ERa, and AROM in freeliving male spotted antbirds across reproductive and nonreproductive seasons in two brain regions known to regulate both reproductive and aggressive behaviors. mRNA expression of ER in the preoptic area and AR in the nucleus taeniae were elevated in male spotted antbirds during the nonbreeding season when circulating T concentrations were low. This unusual seasonal receptor regulation may represent a means for the year-round regulation of vertebrate aggressive behavior via steroids by increasing the brain's sensitivity to sex steroids during the nonbreeding season.

show abstract

Section: Introductionmentioning

confidence: 85%

Section: Ar Era and Arom Expression In Pommentioning

confidence: 99%

Low sex steroids, high steroid receptors: Increasing the sensitivity of the nonreproductive brain

Canoine

Fusani

Schlinger

et al. 2006

Developmental Neurobiology

View full text Add to dashboard Cite

show abstract

“…Although song sparrows are territorial year-round, the hormonal regulation of territorial behavior varies across seasons, shifting from a dependence upon sex steroids produced in the gonads during the breeding season, to dependence upon non-gonadal (perhaps neural) sources of sex steroids during the non-breeding season [6][7][8][9][10][11]. The present study examined whether hormone-sensitive brain regions show different responses in the breeding and non-breeding seasons.…”

Section: Introductionmentioning

confidence: 99%

Neural responses to aggressive challenge correlate with behavior in nonbreeding sparrows

2005

Self Cite

View full text Add to dashboard Cite

The present study was conducted on captive male song sparrows (Melospiza melodia) during the nonbreeding season in order to 1) examine Fos and Zenk responses of basal forebrain sites to simulated territorial intrusion (STI), and 2) determine how those responses relate to aggression. Numerous forebrain areas showed significant Fos and Zenk responses to STI, and in several areas of the hypothalamus and lateral septum, these responses were negatively correlated with aggressive behavior. Homologous areas in mammals show greater responses in subordinate subjects than in dominant subjects. Thus these brain areas may be responsive to social stressors across a wide range of vertebrates.

show abstract

“…Testosterone, in particular, is known to activate and influence reproductive behaviours and aggression in many species of birds and in various contexts (e.g. Silver et al 1979;Harding 1981Harding , 1983Balthazart 1983;Wingfield and Ramenofsky 1985;Wingfield et al 1987Wingfield et al , 2001Schwabl 1992;Soma et al 1999;Canoine and Gwinner 2002). Aggression occurs over limited resources, such as territories and mates, and a modulatory role of testosterone has been demonstrated, mainly in the context of reproductive aggression (Wingfield et al 2006; but see Ros et al 2002 for a role of testosterone in a non-reproductive context).…”

Section: Introductionmentioning

confidence: 99%

European robins (Erithacus rubecula) lack an increase in testosterone during simulated territorial intrusions

Scriba

Goymann

2010

J Ornithol

View full text Add to dashboard Cite

The challenge hypothesis (Wingfield et al. in Am Nat 136:829-846, 1990) predicts that circulating testosterone increases when socially monogamous male birds are challenged during breeding. Although the challenge hypothesis has been confirmed in large-scale interspecific comparisons of seasonal hormone profiles, experimental tests of the challenge hypothesis are still uncommon and the results equivocal. We tested one of the predictions of the challenge hypothesis by investigating the behavioural and hormonal response of freeliving European robins during simulated territorial intrusions (STIs) in the breeding season. We conducted STIs by placing a stuffed decoy in a territory and playing robin song. After the behaviour of the focal male had been recorded for at least 10 min, it was captured and a blood sample was taken immediately. Controls were caught within 10 min of the first response of the territory owner. Hormone concentrations were measured by radioimmunoassay. Although previous studies have shown that testosterone has an impact on aggression, European robins do not respond to STIs by increasing circulating levels of testosterone.

show abstract

Combined Aromatase Inhibitor and Antiandrogen Treatment Decreases Territorial Aggression in a Wild Songbird during the Nonbreeding Season

Cited by 158 publications

References 54 publications

Low sex steroids, high steroid receptors: Increasing the sensitivity of the nonreproductive brain

Low sex steroids, high steroid receptors: Increasing the sensitivity of the nonreproductive brain

Neural responses to aggressive challenge correlate with behavior in nonbreeding sparrows

European robins (Erithacus rubecula) lack an increase in testosterone during simulated territorial intrusions

Contact Info

Product

Resources

About