Edeline Eric, Bardonnet Agnès, Bolliet Valérie, Dufour Sylvie, Elie Pierre
Cemagref, Unité Ecosystèmes Estuariens et Poissons Migrateurs Amphihalins (EPBX), 50 avenue de Verdun, 33612 Cestas Cedex, France.
Horm Behav. 2005 Jun;48(1):53-63. doi: 10.1016/j.yhbeh.2005.02.001. Epub 2005 Mar 17.
Dispersal, one of the most important processes in population ecology, is an issue linking physiological and behavioral features. However, the endocrine control of animal dispersal remains poorly understood. Here, we tested whether and how thyroid hormones may influence dispersal in glass eels of Anguilla anguilla, by testing their influence on locomotor activity and rheotactic behavior. Glass eels were caught during their estuarine migration and treated by immersion in either a l-thyroxine (T(4)) or a thiourea (TU) solution. As measured by radioimmunoassay, T(4) and TU treatments induced, respectively, increased and decreased whole-body thyroid hormone levels relative to untreated controls. We tested a total of 960 glass eels distributed into control, and T(4) and TU treatment groups, on their swimming behavior in experimental flume tanks equipped with upstream and downstream traps that allowed us to concurrently measure both the locomotor activity and the rheotactic behavior. Compared to controls, locomotor activity significantly increased among the hyperthyroid, T(4)-treated eels, but significantly decreased among the hypothyroid, TU-treated eels. The results on rheotactic behavior suggested a more complex regulatory mechanism, since TU but not T(4) treatment significantly affected rheotactic behavior. The influence of thyroid hormones on locomotor activity suggests a central role for these hormones in the regulation of mechanisms leading to the colonization of continental habitats by glass eels. Thyroid hormones are also implicated in the control of locomotor activity in mammals and migratory behavior in birds, suggesting that these hormones represent conserved, proximate mediators of dispersal in vertebrates.
扩散是种群生态学中最重要的过程之一，是一个将生理和行为特征联系起来的问题。然而，动物扩散的内分泌控制仍知之甚少。在这里，我们通过测试甲状腺激素对欧洲鳗鲡玻璃鳗运动活性和趋流行为的影响，来检验甲状腺激素是否以及如何影响其扩散。玻璃鳗在河口洄游期间被捕捞，并通过浸泡在左旋甲状腺素（T4）或硫脲（TU）溶液中进行处理。通过放射免疫测定法测量，相对于未处理的对照组，T4和TU处理分别导致全身甲状腺激素水平升高和降低。我们总共测试了960条玻璃鳗，它们被分为对照组、T4处理组和TU处理组，在配备有上游和下游陷阱的实验水槽中测试它们的游泳行为，这使我们能够同时测量运动活性和趋流行为。与对照组相比，甲状腺功能亢进的T4处理组玻璃鳗的运动活性显著增加，而甲状腺功能减退的TU处理组玻璃鳗的运动活性显著降低。趋流行为的结果表明存在更复杂的调节机制，因为只有TU处理而非T4处理显著影响趋流行为。甲状腺激素对运动活性的影响表明，这些激素在调节玻璃鳗定殖于大陆栖息地的机制中起核心作用。甲状腺激素也参与哺乳动物运动活性的控制和鸟类的迁徙行为，这表明这些激素是脊椎动物中保守的、直接的扩散调节因子。
