Whitfield-Rucker M G, Cassone V M
Department of Biology, Texas A&M University, College Station 77843, USA.
Horm Behav. 1996 Dec;30(4):528-37. doi: 10.1006/hbeh.1996.0056.
Avian song is a sexually dimorphic behavior which is regulated seasonally. This regulation involves the construction and growth of song control structures: the high vocal center (HVC), nucleus robustus archistrialis (RA), nucleus magnocellularis anterior (MAN), and Area X. Song behavior and its neural correlates are controlled by steroid-dependent and independent processes. The avian circadian system is known to be involved in both daily processes and seasonal reproduction. A major part of this system is the circadian secretion of melatonin by the pineal gland. To determine possible interactions of the circadian and song control systems, the distribution and density of 2-[125I]iodomelatonin (IMEL) binding, an indicator of melatonin sensitivity, were determined in male and female house sparrow brains. Specific binding was found in visual system centers of both genders, but binding in HVC, RA, and Area X was present only in males. Binding in MAN was present in both sexes. Although the effects of short and long photoperiods on male house sparrow IMEL binding in song structures revealed no systematic changes, there were significant differences in binding under different photoperiods in HVC and RA. IMEL binding in the tectofugal nucleus rotundus, however, was consistently highest under short day conditions. IMEL binding in song control nuclei was independent of testicular influence, since castration did not affect it significantly. The data point to a role for the circadian system of house sparrows in song control, but a specific role for melatonin in the daily or seasonal regulation of the song control system in birds, could not be determined.
鸟类鸣叫是一种受季节性调节的两性异形行为。这种调节涉及鸣叫控制结构的构建和生长：高级发声中枢（HVC）、古纹状体粗核（RA）、前大细胞核（MAN）和X区。鸣叫行为及其神经关联受类固醇依赖性和非依赖性过程的控制。已知鸟类昼夜节律系统参与日常过程和季节性繁殖。该系统的一个主要部分是松果体昼夜分泌褪黑素。为了确定昼夜节律系统与鸣叫控制系统之间可能的相互作用，在雄性和雌性家麻雀大脑中测定了褪黑素敏感性指标2-[125I]碘褪黑素（IMEL）结合的分布和密度。在两性的视觉系统中枢均发现了特异性结合，但仅在雄性的HVC、RA和X区存在结合。MAN区两性均有结合。尽管短光照周期和长光照周期对雄性家麻雀鸣叫结构中IMEL结合的影响未显示出系统性变化，但在不同光照周期下，HVC和RA中的结合存在显著差异。然而，在短日照条件下，顶盖延髓通路的圆核中的IMEL结合始终最高。鸣叫控制核中的IMEL结合不受睾丸影响，因为去势对其没有显著影响。数据表明家麻雀的昼夜节律系统在鸣叫控制中发挥作用，但无法确定褪黑素在鸟类鸣叫控制系统的日常或季节性调节中的具体作用。
