Rasika S, Nottebohm F, Alvarez-Buylla A
Laboratory of Animal Behavior, Rockefeller University, New York, NY 10021.
Proc Natl Acad Sci U S A. 1994 Aug 16;91(17):7854-8. doi: 10.1073/pnas.91.17.7854.
New neurons are added to the high vocal center (HVC) of adult male and female canaries. Exogenous testosterone induces a marked increase in HVC size in adult female canaries, though the mechanisms responsible for this increase remain unknown. To understand the mechanisms, we analyzed the effects of testosterone on neuronal recruitment in the female HVC. Intact adult female canaries received Silastic implants that were empty or filled with testosterone. Birds in the short-survival group received the Silastic implant, followed by a single injection of [3H]thymidine 2 days later, and were killed on the following day. Birds in the long-survival group were injected once a day for 5 days with [3H]thymidine and received the Silastic implant 20 and 40 days later. These birds were killed 60 days after the first injection of [3H]thymidine. The number of 3H-labeled ventricular zone cells above, rostral, or caudal to HVC was not affected by the hormone treatment in the short-survival birds, suggesting that testosterone did not affect neuronal production. However, the number of 3H-labeled HVC neurons that projected to robust nucleus of the archistriatum (RA) in the long-survival birds was three times greater in the hormone-treated than in the control group, though the total number of RA-projecting cells did not change significantly. Testosterone also induced an increase in the size of the HVC cells that project to RA. Thus, these experiments suggest that testosterone affects the recruitment and/or survival of newly generated RA-projecting HVC neurons but does not affect their production.
成年雄性和雌性金丝雀的高发声中枢（HVC）会添加新的神经元。外源性睾酮会使成年雌性金丝雀的HVC大小显著增加，不过导致这种增加的机制尚不清楚。为了理解相关机制，我们分析了睾酮对雌性HVC中神经元募集的影响。完整的成年雌性金丝雀接受空的或填充有睾酮的硅橡胶植入物。短期存活组的鸟类接受硅橡胶植入物，2天后单次注射[3H]胸腺嘧啶核苷，次日处死。长期存活组的鸟类每天注射一次[3H]胸腺嘧啶核苷，共注射5天，并在20天和40天后接受硅橡胶植入物。这些鸟类在首次注射[3H]胸腺嘧啶核苷60天后处死。在短期存活的鸟类中，激素处理并未影响HVC上方、喙侧或尾侧3H标记的脑室区细胞数量，这表明睾酮不影响神经元的产生。然而，在长期存活的鸟类中，激素处理组投射到古纹状体粗核（RA）的3H标记的HVC神经元数量是对照组的三倍，尽管投射到RA的细胞总数没有显著变化。睾酮还导致投射到RA的HVC细胞大小增加。因此，这些实验表明，睾酮影响新生成的投射到RA的HVC神经元的募集和/或存活，但不影响其产生。
