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Does Leptin Provide a Metabolic Signal to the Reproductive System in Blue-tongued lizards, Tiliqua nigrolutea?
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Animals require adequate energy reserves to fuel successful reproduction: there must, therefore, be a physiological signal that informs the reproductive axis about the body's nutritional state. We aimed to test the hypothesis that leptin provides a metabolic signal to the reproductive system in blue-tongued lizards, a species in which energy intake is constrained by hibernation, and in which the females, but not the males, exhibit a multiennial reproductive cycle. We compared the annual cycles of plasma leptin, and corticosterone, as a second major metabolic hormone, in male and female blue-tongued lizards. In males, plasma corticosterone is high during the spring mating period, lowest during summer, and rises to a significant peak during late hibernation. In both reproductive and non-reproductive females, plasma corticosterone is minimal in spring. In pregnant females corticosterone peaks during late gestation, falling sharply around the time of birth: this pattern is not apparent in non-pregnant females. Plasma leptin concentrations vary between males and females but again, there was no significant difference between the patterns of plasma leptin in reproductive and non-reproductive females. These results suggest that other factors, such as thyroid hormones, may contribute to determining an individual female's decision to breed in any one year.
conference abstract from Australia and New Zealand Society for Comparative Physiologists and Biochemists, Brisbane 2006
|Date Deposited:||19 Jan 2007|
|Last Modified:||18 Nov 2014 03:12|
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