Canonaco M, Tavolaro R, Facciolo R M, Artero C, Franzoni M F
Ecology Department, University of Calabria, Rende (CS), Italy.
J Exp Zool. 1994 Jul 15;269(4):383-8. doi: 10.1002/jez.1402690412.
Quantitative receptor autoradiography was used to study the binding of 2-[125I] iodomelatonin in the brain of the castrated and gonadally intact male Japanese quail Coturnix japonica exposed to both long- and short-day photoperiod cycles. The distribution study displayed that these conditions were responsible for a heterogeneous binding pattern as shown by elevated receptor levels being located in visual brain centers, such as the stratum opticum, nucleus pretectalis, and nucleus geniculatus lateralis, pars ventralis, while lower values were found in the nucleus lateralis hypothalami and nucleus isthmi pars magnocellularis. Closer examination of the 2-[125I] iodomelatonin-binding pattern following the different gonadal and photic influences showed that combination of the gonadally intact condition and a 16L:8D (long-day) photoperiod cycle was required for the greater binding changes. These differences occurred in brain sites such as the area preoptica, paleostriatum primitivum, and nucleus ectomamillaris. Saturation binding studies, which were carried out only in some of the above areas, revealed that the combined gonadal- and photic-induced changes are basically due to the modifications of total number of binding sites. The importance of a gonadal steroid modulatory role in the photic-dependent melatonin binding activity suggests that other types of neuronal mechanisms might be involved in the regulation of neuroendocrine and socio-sexual behaviors in nonmammalian vertebrates.
采用定量受体放射自显影技术，研究了暴露于长日照和短日照光周期的去势和性腺完整雄性日本鹌鹑（Coturnix japonica）大脑中2-[125I]碘褪黑素的结合情况。分布研究显示，这些条件导致了异质性结合模式，视觉脑区如视层、前顶盖核和外侧膝状体腹侧部的受体水平升高，而下丘脑外侧核和峡核大细胞部的值较低。对不同性腺和光照影响下2-[125I]碘褪黑素结合模式的进一步研究表明，性腺完整状态与16L:8D（长日照）光周期相结合，才能产生更大的结合变化。这些差异出现在视前区、原古纹状体和乳头外侧核等脑区。仅在上述部分区域进行的饱和结合研究表明，性腺和光照联合诱导的变化主要是由于结合位点总数的改变。性腺类固醇在光依赖的褪黑素结合活性中的调节作用表明，其他类型的神经元机制可能参与非哺乳类脊椎动物神经内分泌和社会性行为的调节。
