Herichová I, Monosíková J, Zeman M
Department of Animal Physiology and Ethology, Comenius University Bratislava, Mlynská Dolina B2, 84215 Bratislava, Slovakia.
Comp Biochem Physiol A Mol Integr Physiol. 2008 Jan;149(1):44-50. doi: 10.1016/j.cbpa.2007.10.006. Epub 2007 Oct 11.
The chicken pineal gland possesses the capacity to generate circadian oscillations, is able to synchronize to external light:dark cycles and can generate an hormonal output--melatonin. We examined the light responses of the chicken pineal gland and its effects on melatonin and Per2, Bmal1 and E4bp4 expression in 19-day old embryos and hatchlings during the dark phase, subjective light phase and in constant darkness. Expression of Per2 and E4bp4 were rhythmic under light:dark conditions, but the rhythms of E4bp4 and Bmal1 mRNA did not persist in constant darkness in 19-day old embryos. Per2 mRNA expression persisted in constant darkness, but with a reduced amplitude. Per2 expression was inducible by light only during the subjective day. Melatonin release was inhibited by light only at end of the dark phase and during the subjective light phase in embryos. Our data demonstrate that the embryonic avian pineal pacemaker is light sensitive and can generate rhythmic output, however the effects of light were diminished in chick embryos in compared to hatchlings.
鸡松果体具有产生昼夜节律振荡的能力，能够与外部明暗周期同步，并能产生激素输出——褪黑素。我们在黑暗期、主观光照期和持续黑暗条件下，研究了19日龄胚胎和雏鸡松果体的光反应及其对褪黑素、Per2、Bmal1和E4bp4表达的影响。在明暗条件下，Per2和E4bp4的表达具有节律性，但在19日龄胚胎中，E4bp4和Bmal1 mRNA的节律在持续黑暗中并未持续。Per2 mRNA表达在持续黑暗中持续存在，但振幅降低。Per2表达仅在主观白天受光诱导。在胚胎中，褪黑素释放仅在黑暗期结束时和主观光照期受光抑制。我们的数据表明，胚胎期鸟类松果体生物钟对光敏感，能够产生节律性输出，然而与雏鸡相比，光对鸡胚胎的影响较小。
