GONADAL-GABAERGIC INTERACTION IS AN IMPORTANT FACTOR INVOLVED IN PHOTOPERIOD-INDUCED 2-[I-125] IODOMELATONIN BINDING CHANGES IN THE JAPANESE-QUAIL BRAIN
GONADAL-GABAERGIC INTERACTION IS AN IMPORTANT FACTOR INVOLVED IN PHOTOPERIOD-INDUCED 2-[I-125] IODOMELATONIN BINDING CHANGES IN THE JAPANESE-QUAIL BRAIN
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DOI：
10.1016/0361-9230(94)90014-0
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发表时间：
1994-01-01
影响因子：
3.8
通讯作者：
FRANZONI, MF
中科院分区：
文献类型：
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作者：
CANONACO, M;TAVOLARO, R;FRANZONI, MF
褪黑激素单独和/或通过其他假定的神经递质的干预能够控制昼夜节律的机制的类型仍然没有解决。比较2-[I-125] iodomelatonin结合模式在去势和性腺完整的日本鹌鹑（Coturnix japonica）的大脑中，使用定量受体放射自显影，显示完整的性腺条件和长日（16 L：8 D）的光刺激时间表的组合是负责主要的结合变化。事实上，在视交叉上区和外乳头核（p < 0.01）以及视前前核和古纹状体（p < 0.001）中分别获得了高和低的结合水平。在所有脑区中，性腺调节作用并不总是明显的，如长日照光周期在去势和性腺完整的动物的前新纹状体和圆核中产生减少的（p < 0.01）结合水平所揭示的，尽管在相同动物的中央灰质中也发现了升高的值（p < 0.05）。饱和结合的研究表明，性腺和/或光的影响引起的结合位点的数量的变化，而亲和力常数变化只在一些下丘脑网站。在2-[I-125]碘褪黑激素结合水平上的GABA能活性测试表明，这种抑制性神经递质负责增加低受体值。此外，GABA依赖性的影响被证明是通过GABA介导的，受体亚型，因为荷包牡丹碱（该网站的特异性拮抗剂）抑制GABA诱导的褪黑激素结合水平升高，在上述大脑部位的性腺完整的鹌鹑暴露于两个光周期。即使在这种情况下，褪黑激素结合的变化是由于结合位点的数量的变化。在不同光照条件下，GABA能-性腺的明显影响导致2-[I-125] iodomelatonin结合值的变化，提供了其他可能的神经机制的证据，这些机制在神经内分泌活动和社会性行为中引起昼夜节律。
The type of mechanism(s) by which melatonin alone and/or through the intervention of other putative neurotransmitters is able to control circadian rhythms remains unresolved. Comparison of 2-[I-125] iodomelatonin binding pattern in the brain of castrated and gonadally intact Japanese quail (Coturnix japonica), using quantitative receptor autoradiography, displayed that the combination of the intact gonadal condition and a long-day (16L:8D) photostimulatory schedule is responsible for major binding changes. In fact, high and low binding levels were obtained in the suprachiasmatic area and nucleus ectomamillaris (p < 0.01) and in the nucleus preopticus anterior and paleostriatum primitivum (p < 0.001), respectively. A gonadal modulatory role was not always evident in all brain areas as revealed by long-day photic cycles producing diminished (p < 0.01) binding levels in the anterior neostriatum and the nucleus rotundus of both castrated and gonadally intact animals, although elevated values were also found in the substantia grisea centralis (p < 0.05) of the same animals. Saturation binding studies revealed that gonadal and/or photic effects induce alterations in the number of binding sites, whereas the affinity constant varied only in some hypothalamic sites. Testing of GABAergic activity on 2-[I-125] iodomelatonin binding levels showed that this inhibitory neurotransmitter was responsible for increasing low receptor values. Moreover, GABA-dependent influences were shown to be mediated via a GABA, receptor subtype since bicuculline (specific antagonist of this site) inhibited the elevated GABA-induced melatonin binding levels in the above brain sites of the gonadally intact quail exposed to both photoperiod cycles. Even in this case, melatonin binding changes were due to the variations in the number of binding sites. The apparent GABAergic-gonadal influence resulting in changes of the 2-[I-125] iodomelatonin binding values, under the different photic conditions, provides evidences of other probable neural mechanisms that entrain circadian rhythmicity in neuroendocrine activities and in sociosexual behaviors.