Robertson Brian D, Hasstedt Michael R, Vandermeer Caitlin L, MacDougall-Shackleton Scott A
Department of Psychology, Advanced Facility for Avian Research, University of Western Ontario, London, ON N6A 5C2, Canada.
Department of Biology, Advanced Facility for Avian Research, University of Western Ontario, London, ON N6A 5B7, Canada.
Gen Comp Endocrinol. 2014 Aug 1;204:166-72. doi: 10.1016/j.ygcen.2014.04.032. Epub 2014 May 10.
Brain nuclei within the song-control system of songbirds are seasonally plastic during adulthood. These nuclei are larger in birds exposed to long, spring-like days than short, winter-like days. There is overwhelming evidence that this effect is mediated by testosterone (T). However, castration studies have also demonstrated that photostimulation has gonad-independent effects on song-control system plasticity, but these studies rarely control for extra-gonadal sources of T. In this study, we used anti-androgen and anti-estrogen treatments in combination with castration to determine the sex steroid-independent effects of photostimulation on HVC size and doublecortin immunoreactivity in white-throated sparrows (Zonotrichia albicollis). Birds were kept on short days or photostimulated for 1 month. Photostimulated birds were intact, castrated and treated with anti-androgens and anti-estrogens, or castrated and treated with T. HVC volumes of photostimulated birds were significantly larger than short-day birds. HVC volume of castrated birds given anti-androgens/-estrogens was significantly larger than short-day birds, indicating a sex steroid-independent effect of photostimulation. Similar results were observed for RA. The number of migrating neurons (immunoreactive for doublecortin) in HVC did not differ between treatment groups. Our data support the view that photostimulation alone can drive song-control system nuclei growth, and that concurrent exposure to T potentiates this growth. Moreover, these effects do not appear dependent on modulation of neuron migration.
成年鸣禽歌曲控制系统中的脑核在季节上具有可塑性。与暴露在类似冬季的短日照环境中的鸟类相比，暴露在类似春季的长日照环境中的鸟类，这些脑核更大。有大量证据表明，这种效应是由睾酮（T）介导的。然而，去势研究也表明，光刺激对歌曲控制系统可塑性具有性腺非依赖性作用，但这些研究很少控制性腺外的T来源。在本研究中，我们将抗雄激素和抗雌激素处理与去势相结合，以确定光刺激对白喉带鹀（Zonotrichia albicollis）HVC大小和双皮质素免疫反应性的性类固醇非依赖性作用。将鸟类置于短日照环境中或进行1个月的光刺激。光刺激的鸟类保持完整、去势并接受抗雄激素和抗雌激素处理，或去势并接受T处理。光刺激鸟类的HVC体积显著大于短日照鸟类。给予抗雄激素/抗雌激素的去势鸟类的HVC体积显著大于短日照鸟类，表明光刺激具有性类固醇非依赖性作用。对RA也观察到了类似结果。HVC中迁移神经元（双皮质素免疫反应阳性）的数量在各处理组之间没有差异。我们的数据支持这样的观点，即单独的光刺激可以驱动歌曲控制系统核的生长，同时暴露于T会增强这种生长。此外，这些效应似乎不依赖于神经元迁移的调节。
