Androgen-metabolizing enzymes show region-specific changes across the breeding season in the brain of a wild songbird

Soma, Kiran K.; Bindra, Reba K.; Gee, Jennifer M.; Wingfield, John C.; Schlinger, Barney A.

doi:10.1002/(sici)1097-4695(19991105)41:2<176::aid-neu2>3.0.co;2-2

Cited by 103 publications

(36 citation statements)

References 50 publications

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“…Thus, the E2 formed in nT may act transynaptically on other nuclei such as the POM, which is involved in the regulation of song behavior Riters and Ball, 1999;Saldanha et al, 2000;Riters and Alger, 2004). The strong tendency for increased AROM expression in nT in male spotted antbirds occurred during the nonbreeding season when they have low plasma levels of T. This is in contrast with results on temperate birds in which AROM expression (and/or activity) was increased by T-treatment (Fusani et al, 2001) or positively correlated with territorial behavior (Soma et al, 1999a(Soma et al, , 2003. Hence, circulating T levels do not correlate with telencephalic aromatase activity (Fusani et al, 2000;Silverin et al, 2000).…”

Section: Ar and Arom Expression In Ntmentioning

confidence: 70%

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

Canoine

Fusani

Schlinger

et al. 2006

Developmental Neurobiology

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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.

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Section: Ar and Arom Expression In Ntmentioning

confidence: 70%

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

Canoine

Fusani

Schlinger

et al. 2006

Developmental Neurobiology

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“…Further, E2 is effective in stimulating masculine behaviors only when implanted directly into the anterior hypothalamus/preoptic area and not when administered systemically (Mason and Adkins, 1976;Crews et al, 1978;Winkler and Wade, 1998). However, this area accumulates both androgens and estrogens (Martinez-Vargas et al, 1978;Morrell et al, 1979) and, similar to other species (Reddy et al, 1973;Callard et al, 1978aCallard et al, , 1981Roselli et al, 1985;Schlinger and Callard, 1987;Steimer and Hutchison, 1990;Soma et al, 1999), it contains relatively high levels of aromatase activity (Wade, 1997). These studies indicate that the enzyme might play some role in the mediation of male-specific functions other than behavior that are associated with the anterior hypothalamus/preoptic area.…”

Section: Discussionmentioning

confidence: 79%

“…Like green anoles, sex and/or seasonal differences in neuronal aromatase activity have been documented in species ranging from teleosts to mammals (Reddy et al, 1973;Callard et al, 1977Callard et al, , 1981Callard et al, , 1983Roselli et al, 1985;Schlinger and Callard, 1987;Schlinger et al, 1989;Silverin and Deviche, 1991;Soma et al, 1999;Gobbetti et al, 1994). Similar effects on 5␣-reductase have been detected in a few cases.…”

Section: Discussionmentioning

confidence: 85%

Androgen Metabolism in the Brain of the Green Anole Lizard (Anolis carolinensis): Effects of Sex and Season

Rosen

Wade

2001

General and Comparative Endocrinology

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“…We used DHT and E 2 instead of T to directly and selectively activate ARs and ERs, and because the efficiency of T metabolism to DHT and/or E 2 may vary with photoperiod (Soma et al, 1999a(Soma et al, , 2003Riters et al, 2001;Forlano et al, 2006). We used plastic tubing (Scientific Commodities, Lake Havasu City, AZ) (85 durometer vinyl; 0.068 mm i.d.…”

Section: Osmotic Pump and Intracerebral Infusions Surgerymentioning

confidence: 99%

Steroid Hormones Act Transsynaptically within the Forebrain to Regulate Neuronal Phenotype and Song Stereotypy

Meitzen¹,

Moore²,

Lent³

et al. 2007

J. Neurosci.

102

164

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Steroid sex hormones induce dramatic seasonal changes in reproductive related behaviors and their underlying neural substrates in seasonally breeding vertebrates. For example, in adult white-crowned sparrows, increased Spring photoperiod raises circulating testosterone, causing morphological and electrophysiological changes in song-control nuclei, which modify song behavior for the breeding season. We investigated how photoperiod and steroid hormones induce these changes in morphology, electrophysiology, and behavior. Neurons in a song premotor nucleus, the robust nucleus of the arcopallium (RA), show increased intrinsic spontaneous firing rate and soma size when birds are in breeding condition. Using combinations of systemic and unilateral local intracerebral hormonal manipulations, we show that long-day photoperiod accelerates the effects of systemic testosterone on RA neurons via the estradiol-synthesizing enzyme aromatase (CYP19A1); these changes require inputs from the afferent song control nucleus HVC (used as a proper name) and steroid receptor activation within HVC; local coactivation of androgen and estrogen receptors (ARs and ERs, respectively) within HVC, but not RA, is sufficient to cause neuronal changes in RA; activation of ARs in RA is also permissive. Using bilateral local intracerebral hormone-receptor blockade, we found that ARs and ERs in the song-control nucleus HVC mediate systemic testosterone-induced changes in song stereotypy but not rate. This novel transsynaptic effect of gonadal steroids on activity and morphology of RA neurons is part of a concerted change in key premotor nuclei, enabling stereotyped song.

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Androgen-metabolizing enzymes show region-specific changes across the breeding season in the brain of a wild songbird

Cited by 103 publications

References 50 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

Androgen Metabolism in the Brain of the Green Anole Lizard (Anolis carolinensis): Effects of Sex and Season

Steroid Hormones Act Transsynaptically within the Forebrain to Regulate Neuronal Phenotype and Song Stereotypy

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