Sex differences in estrogen-induced progesterone and estrogen receptor mRNA in the ventromedial hypothalamus of hatchling whiptail lizards

Wennstrom, Kira L.; Gill, Cynthia J.; Crews, David

doi:10.1016/s0165-3806(03)00225-6

Cited by 14 publications

(9 citation statements)

References 39 publications

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“…However, the virago does not exhibit an enlarged POA/AH as do males of the ancestral species (Wennstrom et al, 1999). The virago also does not show another sexually dimorphic response characteristic of the ancestral sexual species, namely, upregulation of progesterone receptor in the ventromedial hypothalamus in response to exogenous estrogen (Wennstrom et al, 2003).…”

mentioning

confidence: 84%

Testosterone Stimulates Mounting Behavior and Arginine Vasotocin Expression in the Brain of both Sexual and Unisexual Whiptail Lizards

Hillsman¹,

Sanderson²,

Crews³

2006

Sex Dev

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In nonmammalian vertebrates the abundance of arginine vasotocin (AVT) neurons in the brain is sexually dimorphic, a pattern that is modulated by testicular androgen. This peptide is thought to be involved in the control of male-typical mounting behaviors. The all-female desert-grasslands whiptail (Cnemidophorus uniparens) reproduces by obligate parthenogenesis and in nature no males exist, but eggs treated with aromatase inhibitor hatch into individuals (called virago C. uniparens) having testes, accessory sex structures, high circulating concentrations of androgens, and exhibiting only male-like copulatory behavior. To examine the ‘sexual’ dimorphism of AVT-containing neurons in these animals, we compared AVT immunoreactivity in gonadectomized control and virago C. uniparens, with that of gonadectomized male and female Cnemidophorus inornatus, a sexual species that is the maternal ancestor to the parthenogenetic species. Mounting behavior is elicited in both species and both sexes by testosterone, and it was predicted that the distribution and abundance of AVT cell bodies and fibers would reflect the propensity of males and females of the two species to display male-typical copulatory behavior. Since both this propensity and AVT abundance are controlled by androgens, we compared testosterone-implanted and control animals within each group. Testosterone treatment generally increased AVT abundance, except in lab-reared parthenoforms, in which testosterone treatment was the least effective in inducing male-like copulatory behavior.

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mentioning

confidence: 84%

Testosterone Stimulates Mounting Behavior and Arginine Vasotocin Expression in the Brain of both Sexual and Unisexual Whiptail Lizards

Hillsman¹,

Sanderson²,

Crews³

2006

Sex Dev

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“…The first results from these experiments show distinct differences in estrogen receptor expression and progesterone concentrations in specifie areas of the central nervous system, a finding that may imply that aromatase regulation is only the first step in a sequence of severa! more complex sex-specific/dimorphic genetic phenomena that still remain to be examined (Wennstrom et al, 2003).…”

Section: Vertebrates a Reptilesmentioning

confidence: 99%

Molecular Mechanism of Sry Action During Testicular Differentiation in the Mouse

Tavallaee¹,

Li²,

Lau³

et al. 2007

Biology of Reproduction

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“…In the case of lizards, an attempt has also been made to examine sexual dimorphism in the brain. The first results from these experimental series show distinct differences in estrogen receptor expression and progesterone concentrations in specific areas of the central nervous system, a finding that may imply that aromatase regulation is only the first step in a sequence of several more complex sex-specific/dimorphic genetic phenomena that still remain to be examined [28]. …”

Section: Vertebratesmentioning

confidence: 99%

“…The study of sex steroid concentrations and the presence of their receptors in various parts of the CNS has already been attempted in various species, including mammals and reptiles. After all, the role of androgens and estrogens in sexual differentiation in vertebrates is a classic concept that modern research data has only supported and expanded, rather than criticize [5,28]. For instance, aromatase regulation appears to be the final target in the sex determination circuit of several turtles.…”

Section: Mammalsmentioning

confidence: 99%

Molecular patterns of sex determination in the animal kingdom: a comparative study of the biology of reproduction

Manolakou¹,

Lavranos²,

Angelopoulou³

2006

Reprod Biol Endocrinol

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Determining sexual fate is an integral part of reproduction, used as a means to enrich the genome. A variety of such regulatory mechanisms have been described so far and some of the more extensively studied ones are being discussed.For the insect order of Hymenoptera, the choice lies between uniparental haploid males and biparental diploid females, originating from unfertilized and fertilized eggs accordingly. This mechanism is also known as single-locus complementary sex determination (slCSD). On the other hand, for Dipterans and Drosophila melanogaster, sex is determined by the ratio of X chromosomes to autosomes and the sex switching gene, sxl. Another model organism whose sex depends on the X:A ratio, Caenorhabditis elegans, has furthermore to provide for the brief period of spermatogenesis in hermaphrodites (XX) without the benefit of the "male" genes of the sex determination pathway.Many reptiles have no discernible sex determining genes. Their sexual fate is determined by the temperature of the environment during the thermosensitive period (TSP) of incubation, which regulates aromatase activity. Variable patterns of sex determination apply in fish and amphibians. In birds, while sex chromosomes do exist, females are the heterogametic (ZW) and males the homogametic sex (ZZ). However, we have yet to decipher which of the two (Z or W) is responsible for the choice between males and females.In mammals, sex determination is based on the presence of two identical (XX) or distinct (XY) gonosomes. This is believed to be the result of a lengthy evolutionary process, emerging from a common ancestral autosomal pair. Indeed, X and Y present different levels of homology in various mammals, supporting the argument of a gradual structural differentiation starting around the SRY region. The latter initiates a gene cascade that results in the formation of a male. Regulation of sex steroid production is also a major result of these genetic interactions. Similar observations have been described not only in mammals, but also in other vertebrates, emphasizing the need for further study of both normal hormonal regulators of sexual phenotype and patterns of epigenetic/ environmental disruption.

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Sex differences in estrogen-induced progesterone and estrogen receptor mRNA in the ventromedial hypothalamus of hatchling whiptail lizards

Cited by 14 publications

References 39 publications

Testosterone Stimulates Mounting Behavior and Arginine Vasotocin Expression in the Brain of both Sexual and Unisexual Whiptail Lizards

Testosterone Stimulates Mounting Behavior and Arginine Vasotocin Expression in the Brain of both Sexual and Unisexual Whiptail Lizards

Molecular Mechanism of Sry Action During Testicular Differentiation in the Mouse

Molecular patterns of sex determination in the animal kingdom: a comparative study of the biology of reproduction

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