Reproductive and thyroid hormone profiles in captive Western fence lizards (Sceloporus occidentalis) after a period of brumation

Publication Type:
Journal Article
Year of Publication:
Sandra M. Brasfield, Larry G. Talent, David M. Janz
Zoo Biology
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Abstract 10.1002/zoo.20159.abs Seasonal fluctuation in serum concentrations of sex steroid (testosterone [T] and 17β-estradiol [E2]) and thyroid (triiodothyronine [T3] and thyroxine [T4]) hormones was determined in captive Western fence lizards (Sceloporus occidentalis). Samples were collected from male and female breeding pairs weekly for a 4-month period after their emergence from artificial brumation. Circulating levels of E2 corresponded with the expected vitellogenic and ovulatory cycles in females, and surprisingly, E2 in males followed a similar pattern, indicating a possible role in breeding behavior. Serum T was elevated in male lizards for the first 6 weeks after emergence from brumation, possibly related to an increase in the onset of active spermatogenesis. Thyroid hormones showed little cyclical activity throughout the breeding period, with the exception of small increases of T3 at weeks 8 and 16, possibly implying an active role of this hormone with ovulation in females. Overall, these baseline hormone data are not only useful in developing this animal as a laboratory reptile model for assessment of endocrine-mediated toxicity, but also of value for understanding herpetological endocrinology and for application in the conservation of threatened species. Zoo Biol 27:36–48, 2008. © 2007 Wiley-Liss, Inc.


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