Gahr M, Kosar E
Max-Planck-Institut für Verhaltensphysiologie, Seewiesen, Federal Republic of Germany.
J Comp Neurol. 1996 Apr 1;367(2):308-18. doi: 10.1002/(SICI)1096-9861(19960401)367:2<308::AID-CNE11>3.0.CO;2-M.
In many avian species, singing is a circadian or seasonal behavior that appears to be widely dependent on gonadal steroid hormones. To explore the possibility of a further hormone-dependent vocal control mechanism driven by the action of melatonin, we examined the binding of iodinated melatonin (IMEL) in the vocal control network of adult and juvenile (22- and 40-day-old) zebra finches. IMEL binding areas of the zebra finch brain were localized and characterized by using quantitative in vitro autoradiography. In the vocal control system, dense IMEL binding sites were restricted to the nucleus hyperstriatalis ventrale, pars caudalis (HVC). The binding of IMEL to the HVC and to visual areas, e.g., the ectostriatum and the optic tectum, was saturable and showed a single class of high-affinity binding sites with binding affinities (Kds) in the range of 5-20 pM. Competition experiments with various indols and IMEL showed that the IMEL binding site in the zebra finch brain has properties similar to the high-affinity melatonin receptor described in the chicken, in the house sparrow, and in the mammalian brain and retina. Similar to the zebra finch HVC, the HVC of other songbirds, e.g., male canaries and male house sparrows, has the most intense IMEL binding of all areas of the vocal control network. The IMEL binding in the forebrain vocal control areas of the zebra finch, but not that in the visual processing areas, was sexually dimorphic in correlation with the sexually dimorphic neuroanatomy of the forebrain vocal control areas. In the HVC, there is a developmental increase in the maximal number of binding sites for IMEL and in the protein content, so that the adult phenotype of dense IMEL binding develops between day 40 and day 80. The distribution and developmental pattern of IMEL binding in the song system suggests that melatonin has a role in the motor control of singing. Melatonin binding sites in HVC could link HVC-based song control to circadian and circannual changes in the photoperiod independent of gonadal steroids.
在许多鸟类物种中，鸣叫是一种昼夜节律或季节性行为，似乎广泛依赖于性腺类固醇激素。为了探索褪黑素作用驱动的另一种激素依赖性发声控制机制的可能性，我们检测了成年和幼年（22日龄和40日龄）斑胸草雀发声控制网络中碘化褪黑素（IMEL）的结合情况。通过定量体外放射自显影对斑胸草雀脑内的IMEL结合区域进行定位和特征描述。在发声控制系统中，密集的IMEL结合位点局限于腹侧尾端上纹状体核（HVC）。IMEL与HVC以及视觉区域（如外纹状体和视顶盖）的结合是可饱和的，显示出一类高亲和力结合位点，其结合亲和力（解离常数Kds）在5 - 20 pM范围内。用各种吲哚与IMEL进行的竞争实验表明，斑胸草雀脑中的IMEL结合位点具有与鸡、家麻雀以及哺乳动物脑和视网膜中描述的高亲和力褪黑素受体相似的特性。与斑胸草雀的HVC类似，其他鸣禽（如雄性金丝雀和雄性家麻雀）的HVC在发声控制网络的所有区域中具有最强的IMEL结合。斑胸草雀前脑发声控制区域的IMEL结合存在性别差异，与前脑发声控制区域的性别差异神经解剖结构相关，而视觉处理区域则不存在这种差异。在HVC中，IMEL结合位点的最大数量和蛋白质含量在发育过程中增加，因此在第40天到第80天之间形成了密集IMEL结合的成年表型。鸣唱系统中IMEL结合的分布和发育模式表明，褪黑素在鸣叫的运动控制中起作用。HVC中的褪黑素结合位点可以将基于HVC的鸣叫控制与光周期的昼夜节律和年周期变化联系起来，而与性腺类固醇无关。
