Androgen level and male social status in the African cichlid, Astatotilapia burtoni

Parikh, Victoria N.; Clement, Tricia S.; Fernald, Russell D.

doi:10.1016/j.bbr.2005.07.011

Cited by 113 publications

(106 citation statements)

References 17 publications

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“…The reasons for the discrepancy between the studies is not clear, although it suggests that GnRH-R1 mRNA expression is highly labile and may be regulated by factors in addition to social status. In the testes, we found no evidence that reproductive capacity was associated with changes in expression of ARs or ERs, in spite of the fact that enlarged testes are associated with increased production of mature sperm (Fraley and Fernald, 1982) and increased androgen production (Parikh et al, 2006).One of the striking aspect of our results was the fact that, in the anterior brain, expression of all ARs and ERs were regulated by reproductive capacity: all but ER-α were expressed at higher (You and Yin, 2000), implies that the anterior part of the brain could have increased sensitivity to steroid hormones. Such increased sensitivity may enhance the well described negative feedback responses of GnRH1 neurons to circulating steroid levels (e.g., Soma et al, 1996), or increase steroid sensitivity of brain regions involved in behavior.…”

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confidence: 75%

“…Ultimately, dominance affects testes size through regulation of gonadotropin-releasing hormone 1 (GnRH1) production by neurons in the anterior parvocellular preoptic nucleus (aPPn) of the hypothalamus (Davis and Fernald, 1990;Francis et al, 1993;White et al, 2002). The enlarged testes of dominant males contain a higher proportion of mature sperm (Fraley and Fernald, 1982), and produce higher levels of testicular hormones, including 11-ketotestosterone and testosterone (Parikh et al, 2006). The higher levels of circulating androgens in dominant males have behavioral (Francis et al, 1992) and physiological (Soma et al, 1996) consequences.…”

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confidence: 99%

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Social dominance regulates androgen and estrogen receptor gene expression

Burmeister

Kailasanath

Fernald

2007

Hormones and Behavior

112

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In Astatotilapia burtoni, dominant males have higher levels of sex steroid hormones than subordinate males. Because of the complex regulatory interactions between steroid hormones and receptors, we asked whether dominance is also associated with variation in sex steroid receptor gene expression. Using quantitative PCR, we compared the expression of specific subtypes of androgen (AR) and estrogen (ER) receptor genes between dominant and subordinated males in 3 divisions of the brain, the pituitary, and the testes. We measured mRNA levels of AR-α, AR-β, ER-α, ER-βa, and ER-βb, gonadotropin releasing hormone 1 (GnRH1), and GnRH receptor 1 (GnRH-R1) relative to 18S rRNA. In the anterior part of the brain, we found that dominant males had higher mRNA expression of AR-α, AR-β, ER-βa, and ER-βb, but not ER-α, compared to subordinate males. This effect of dominance was reflected in a positive correlation between testes size and AR-α, AR-β, ER-βa, and ER-βb in the anterior brain. In addition, mRNA levels of all ARs and ERs in the anterior brain were positively correlated with mRNA level of GnRH1. In the middle and posterior portions of the brain, as well as the testes, steroid receptor mRNA levels were similar among dominants and subordinates. In the pituitary, ER-α mRNA level was positively correlated with testes size and AR-α mRNA was positively correlated with GnRH-R1 mRNA level. These data suggest that dominant male brains could be more sensitive to sex steroids, which may contribute to the increased complexity of the behavioral repertoires of dominant males. Keywordssteroid hormone receptor; testosterone; estradiol; social dominance; evolution; cichlid; teleost; fish In the cichlid fish Astatotilapia (Haplochromis) burtoni, social status regulates male fertility by controlling the brain-pituitary-gonad (BPG) axis. Consequently, dominant males have 40% larger testes relative to body size compared with subordinate males. Ultimately, dominance affects testes size through regulation of gonadotropin-releasing hormone 1 (GnRH1) production by neurons in the anterior parvocellular preoptic nucleus (aPPn) of the hypothalamus (Davis and Fernald, 1990;Francis et al., 1993;White et al., 2002). The enlarged testes of dominant males contain a higher proportion of mature sperm (Fraley and Fernald, 1982), and produce higher levels of testicular hormones, including 11-ketotestosterone and testosterone (Parikh et al., 2006). The higher levels of circulating androgens in dominant males have behavioral (Francis et al., 1992) and physiological (Soma et al., 1996) consequences. ToCorrespondence to SSB at current address: Department of Biology, University of North Carolina, Chapel Hill, NC 27599, phone: 919-843-5105; fax: 919-962-1625, sburmeister@unc.edu. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting pro...

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contrasting

confidence: 75%

mentioning

confidence: 99%

Social dominance regulates androgen and estrogen receptor gene expression

Burmeister

Kailasanath

Fernald

2007

Hormones and Behavior

112

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“…However, in animals that experienced a somewhat longer sustained social stress for 24 h, we found several differences. As expected, the circulating cortisol level increased significantly, while the circulating testosterone level dropped significantly, both of which are consistent with the steady-state differences measured between the T and NT phenotypes in longer-term experiments (Fox et al 1997, Parikh et al 2006. GnRH1 gene expression surprisingly increased significantly.…”

Section: Discussionsupporting

confidence: 87%

“…For example, T males in stable conditions have low cortisol (Fox et al 1997) and have higher testosterone and 11-KT levels (Parikh et al 2006) as compared with NT males. In the HPG axis, T males have higher levels of the key signaling peptide, GnRH1 and its mRNA (White et al 2002), higher levels of GnRH-R1 mRNA (Au et al 2006), and larger gonads (Davis & Fernald 1990) than NT males.…”

Section: Discussionmentioning

confidence: 99%

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Physiological consequences of social descent: studies in Astatotilapia burtoni

Parikh¹,

Clement²,

Fernald³

2006

Journal of Endocrinology

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In many species, social interactions regulate reproductive capacity, although the exact mechanisms of such regulation are unclear. Since social stress is often related to reproductive regulation, we measured the physiological signatures of change in reproductive state as they relate to short-term stress and the stress hormone cortisol. We used an African cichlid fish, Astatotilapia burtoni, with two distinct, reversible male phenotypes: dominant (territorial, T) males that are larger, more brightly colored, more aggressive, and reproductively competent and non-dominant males (non-territorial, NT) that are smaller, camouflage colored, and have regressed gonads. Male status, and hence reproductive competence, depends on social experience in this system. Specifically, if a T male is placed among larger male fish, it quickly becomes NT in behavior and coloration, but complete regression of its reproductive axis takes ca. 3 weeks (White et al. 2002). Reproduction in all vertebrates is controlled by the hypothalamic-pituitary-gonadal axis in which the key signaling molecule from the brain to the pituitary is GnRH1. Here, we subjected T males to territory loss, a social manipulation which results in status descent. We measured the effects of this status change in levels of circulating cortisol and testosterone as well as mRNA levels of GnRH1 and GnRH receptor-1 (GnRH-R1) in the brain and pituitary, respectively. Following short-term social suppression (4 h), no change was observed in plasma cortisol level, GnRH1 mRNA expression, GnRH-R1 mRNA expression, or plasma testosterone level. However, following a somewhat longer social suppression (24 h), cortisol and GnRH1 mRNA levels were significantly increased, and testosterone levels were significantly decreased. These results suggest that in the short run, deposed T males essentially mount a neural 'defense' against loss of status.

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Conspecific Odors as Sexual Ornaments with Dual Functions in Fishes

Corkum

Cogliati

2014

Fish Pheromones and Related Cues

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Androgen level and male social status in the African cichlid, Astatotilapia burtoni

Cited by 113 publications

References 17 publications

Social dominance regulates androgen and estrogen receptor gene expression

Social dominance regulates androgen and estrogen receptor gene expression

Physiological consequences of social descent: studies in Astatotilapia burtoni

Conspecific Odors as Sexual Ornaments with Dual Functions in Fishes

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