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

Rosen, Greta J.; Wade, Juli

doi:10.1006/gcen.2001.7616

Cited by 28 publications

(20 citation statements)

References 62 publications

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“…Given that we focus solely on testosterone, our results must be interpreted with the caveat that many other factors could influence the traits we measured. This list includes but is not limited to (1) the metabolism of testosterone to other behaviorally relevant hormones (e.g., estradiol, dihydrotestosterone; Winkler and Wade 1998;Rosen and Wade 2001), (2) the importance of tissue sensitivity (e.g., androgen receptor expression) rather than circulating androgen levels per se (Holmes and Wade 2005), and (3) interactions with other signaling pathways, such as the endocrine stress axis the or somatotrophic axis. However, to the extent that testosterone varies in a seasonal and sex-specific fashion and is likely to interact with these factors, it remains a promising mechanism for the integration of this complexity.…”

Section: Discussionmentioning

confidence: 99%

Manipulating Testosterone to Assess Links between Behavior, Morphology, and Performance in the Brown Anole Anolis sagrei

Cox

Stenquist²,

Henningsen³

et al. 2009

Physiological and Biochemical Zoology

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Survival and reproductive success are determined by the complex interplay between behavior, physiology, morphology, and performance. When optimal trait combinations along these various phenotypic axes differ between sexes or across seasons, regulatory mechanisms such as sex steroids can often facilitate sex-specific and/or seasonal trait expression. In this study, we used surgical castration and replacement of exogenous testosterone in adult male brown anoles (Anolis sagrei) to simultaneously examine the effects of testosterone on a suite of morphological (dewlap area, body size), physiological (immune function), behavioral (dewlap, head bob, and push-up displays), and performance (stamina, sprint speed, bite force) traits. We show that testosterone increases (or castration reduces) growth rate, dewlap area, and bite force. Treatment effects on bite force may simply reflect underlying treatment differences in growth combined with allometry of bite force. Other traits, such as stamina, sprint speed, and rate of behavioral displays, were largely independent of circulating testosterone levels. Although we did not observe significant treatment effects on immune function, we found negative correlations between growth and immune function consistent with the hypothesis that testosterone mediates trade-offs between these competing aspects of energy allocation. Overall, our results demonstrate that testosterone can exert pleiotropic effects on a variety of morphological, physiological, behavioral, and performance traits that are known to influence survival and reproductive success.

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Section: Discussionmentioning

confidence: 99%

Manipulating Testosterone to Assess Links between Behavior, Morphology, and Performance in the Brown Anole Anolis sagrei

Cox

Stenquist²,

Henningsen³

et al. 2009

Physiological and Biochemical Zoology

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“…For example, aromatase activity is greater in whole brain homogenates from breeding compared to non-breeding adult male green anoles [73]. Aromatase activity (estradiol) is not required for the display of masculine behavior in this species [94]; T itself is the most potent activator of male sexual behavior [87].…”

Section: Summary and Comparison To Previous Anole Workmentioning

confidence: 93%

Courtship and copulation in the adult male green anole: Effects of season, hormone and female contact on reproductive behavior and morphology

Neal

Wade

2007

Behavioural Brain Research

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Interactions among reproductive season, testosterone (T) and female presence were investigated on the structure and function of forebrain and neuromuscular systems controlling courtship and copulation in the green anole lizard. Under breeding (BS) or non-breeding (NBS) environmental conditions, male green anoles were implanted with either T or blank capsules and exposed to one of three female stimulus conditions: physical, visual or no female contact. T and at least visual exposure to females increased courtship displays (extension of a throat fan, or dewlap), and these effects were greater during the BS than NBS. T also facilitated copulation, and did so to a greater extent in the BS. The hormone increased soma size in the preoptic area (POA) and amygdala (AMY), and in the AMY the effects were greater in the BS than NBS. Cross-sectional areas of copulatory organs and associated muscle fibers were enhanced by T, and more so in the BS than NBS. However, no effects on morphology of dewlap motoneurons or muscles or copulatory motoneurons were detected. Thus, (1) changes in behavior and neural and/or muscular morphology are not always parallel and (2) differences in responsiveness to T exist across seasons and among tissues.

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“…For example, compared to other regions, 5a-reductase activity is increased in the brainstem which contains the dewlap motoneurons (Wade, 1997), but in both whole brain and brainstem, it is equivalent between the sexes and across the breeding and non-breeding seasons. Aromatase activity is relatively high in the hypothalamus and POA, but despite not being critical for masculine sexual behavior, its activity is greater in males than females during the breeding season, and greater in breeding than in non-breeding males (Rosen and Wade, 2001). This pattern, consistent with T up-regulating aromatase activity, is similar to that of other vertebrate species (see Rosen and Wade, 2001; as well as Balthazart, 1997;Lephart, 1996), suggesting that evolutionary conservation is a prominent feature of the mechanisms regulating enzyme activity, but that a correlation with the behavioral importance of the enzyme does not always exist.…”

Section: Hormonal Control Of Reproductive Behaviorsmentioning

confidence: 98%

Current research on the behavioral neuroendocrinology of reptiles

Wade

2005

Hormones and Behavior

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

Cited by 28 publications

References 62 publications

Manipulating Testosterone to Assess Links between Behavior, Morphology, and Performance in the Brown Anole Anolis sagrei

Manipulating Testosterone to Assess Links between Behavior, Morphology, and Performance in the Brown Anole Anolis sagrei

Courtship and copulation in the adult male green anole: Effects of season, hormone and female contact on reproductive behavior and morphology

Current research on the behavioral neuroendocrinology of reptiles

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