Testosterone selectively affects aromatase and 5α-reductase activities in the green anole lizard brain

Cohen, Rachel E.; Wade, Juli

doi:10.1016/j.ygcen.2009.11.006

Cited by 19 publications

(17 citation statements)

References 49 publications

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“…Activity is higher in the brainstem than the forebrain, and whole brain activity does not differ between the sexes or the seasons in gonadally intact animals [Rosen and Wade, 2001;Wade, 1997]. However, T treatment increases whole-brain 5 ␣ R activity in gonadectomized males [Cohen and Wade, 2010].…”

Section: Introductionmentioning

confidence: 93%

Distribution of Two Isozymes of 5α-Reductase in the Brains of Adult Male and Female Green Anole Lizards

Cohen

Wade²

2010

Brain Behav Evol

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The 5α-reductase (5αR) enzyme converts testosterone to 5α-dihydrotestosterone. This local metabolism within the brain is important for the full expression of male sexual behavior in many species, including green anole lizards. Two isozymes of 5αR exist and little is known about their specific distributions. We conducted in situ hybridization for both isozymes in intact male and female green anole brains during the breeding (BS) and non-breeding (NBS) seasons. 5αR1 mRNA was only detected in the brainstem, while 5αR2 was expressed in specific areas throughout the brain. As our primary interest was evaluating the potential role of 5αR in forebrain regulation of reproductive behavior, we quantified 5αR2 expression in the preoptic area, amygdala (AMY), and ventromedial hypothalamus (VMH). More 5αR2 cells were detected during the NBS than BS in the AMY, and the density of these cells was greater in females than males. In the VMH, the right side contained more 5αR2 cells than the left, an effect driven by a lateralized increase in the NBS. These data expand understanding of the distribution and potential roles of both isozymes in the adult brain, and differences in expression patterns between mammals and birds suggest that they may have been co-opted for different functions later in evolution.

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Section: Introductionmentioning

confidence: 93%

Distribution of Two Isozymes of 5α-Reductase in the Brains of Adult Male and Female Green Anole Lizards

Cohen

Wade²

2010

Brain Behav Evol

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“…After the animals were acclimated to the laboratory, males and females were injected with 10 μl of 0.2% lidocaine before being anesthetized with isoflurane, then bilaterally gonadectomized while on ice. During this procedure animals were subcutaneously implanted with a Silastic capsule (7 mm long × 0.7 mm inner diameter × 1.65 mm outer diameter) containing either 5 mm of packed TP or left blank, as in previous studies [Holmes and Wade, 2005;Neal and Wade, 2007;Cohen and Wade, 2010]. This hormonal manipulation produces detectable plasma concentrations that average 48.69 ± 4.78 (SEM) ng/ml, with no difference across seasons [Cohen and Wade, 2012].…”

Section: Treatment and Tissue Collectionmentioning

confidence: 99%

“…20 ng/ml in the BS and 11 ng/ml in the NBS); however, they overlap with the range seen in breeding individuals [Lovern et al, 2001]. This dose was chosen because it reliably activates male sexual behavior and facilitates biochemical and morphological changes in the brain [Neal and Wade, 2007;Cohen and Wade, 2010]. These animals were euthanized by rapid decapitation and the brains were collected 1 week after treatment.…”

Section: Treatment and Tissue Collectionmentioning

confidence: 99%

Relationships among Sex, Season and Testosterone in the Expression of Androgen Receptor mRNA and Protein in the Green Anole Forebrain

Kerver

Wade

2014

Brain Behav Evol

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Sexual behavior in male green anole lizards is regulated by a seasonal increase in testosterone (T). However, T is much more effective at activating behavioral, morphological and biochemical changes related to reproduction in the breeding season (BS; spring) compared to nonbreeding season (NBS; fall). An increase in androgen receptor (AR) during the BS is one potential mechanism for this differential responsiveness. AR expression has not been investigated in specific brain regions across seasons in anoles. The present studies were designed to determine relative AR expression in areas important for male (preoptic area, ventromedial amygdala) and female (ventromedial hypothalamus) sexual behavior, as well as whether T upregulates AR in the anole brain. In situ hybridization and Western blot analyses were performed in unmanipulated animals across sex and season, as well as in gonadectomized animals with and without T treatment. Among hormone-manipulated animals, more cells expressing AR mRNA were detected in females than males in the amygdala. T treatment increased the volume of the ventromedial hypothalamus of gonadectomized animals in the BS, but not the NBS. AR protein in dissections of the hypothalamus and preoptic area was increased in males compared to females specifically in the BS. Additionally, among females, it was increased in the NBS compared to the BS. Collectively, these results indicate that differences in central AR expression probably do not facilitate a seasonal responsiveness to T. However, they are consistent with a role for AR in regulating some differences between sexes in the display of reproductive behaviors.

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“…Testosterone treatment in males of this species also produces enhanced SRD5A activity regardless of the season but only up-regulates aromatase activity during the breeding season. Interestingly, comparable responses are absent in testosterone-treated females (Cohen and Wade 2010). This latter response might be considered an activational effect of testosterone as it occurs during the adult period.…”

Section: Introductionmentioning

confidence: 94%

Neuroendocrine disruption of organizational and activational hormone programming in poikilothermic vertebrates

Rosenfeld

Denslow

Orlando

et al. 2017

Journal of Toxicology and Environmental Health, Part B

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In vertebrates, sexual differentiation of the reproductive system and brain is tightly orchestrated by organizational and activational effects of endogenous hormones. In mammals and birds, the organizational period is typified by a surge of sex hormones during differentiation of specific neural circuits; whereas activational effects are dependent upon later increases in these same hormones at sexual maturation. Depending on the reproductive organ or brain region, initial programming events may be modulated by androgens or require conversion of androgens to estrogens. The prevailing notion based upon findings in mammalian models is that male brain is sculpted to undergo masculinization and defeminization. In absence of these responses, the female brain develops. While timing of organizational and activational events vary across taxa, there are shared features. Further, exposure of different animal models to environmental chemicals such as xenoestrogens such as bisphenol A- BPA and ethinylestradiol- EE2, gestagens, and thyroid hormone disruptors, broadly classified as neuroendocrine disrupting chemicals (NED), during these critical periods may result in similar alterations in brain structure, function, and consequently, behaviors. Organizational effects of neuroendocrine systems in mammals and birds appear to be permanent, whereas teleost fish neuroendocrine systems exhibit plasticity. While there are fewer NED studies in amphibians and reptiles, data suggest that NED disrupt normal organizational-activational effects of endogenous hormones, although it remains to be determined if these disturbances are reversible. The aim of this review is to examine how various environmental chemicals may interrupt normal organizational and activational events in poikilothermic vertebrates. By altering such processes, these chemicals may affect reproductive health of an animal and result in compromised populations and ecosystem-level effects.

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Testosterone selectively affects aromatase and 5α-reductase activities in the green anole lizard brain

Cited by 19 publications

References 49 publications

Distribution of Two Isozymes of 5α-Reductase in the Brains of Adult Male and Female Green Anole Lizards

Distribution of Two Isozymes of 5α-Reductase in the Brains of Adult Male and Female Green Anole Lizards

Relationships among Sex, Season and Testosterone in the Expression of Androgen Receptor mRNA and Protein in the Green Anole Forebrain

Neuroendocrine disruption of organizational and activational hormone programming in poikilothermic vertebrates

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