Circadian change in tryptophan hydroxylase protein levels within the rat intergeniculate leaflets and raphe nuclei
Circadian change in tryptophan hydroxylase protein levels within the rat intergeniculate leaflets and raphe nuclei
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DOI：
10.1016/j.neuroscience.2004.01.031
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发表时间：
2004-01-01
期刊：
影响因子：
3.3
通讯作者：
Raison, S
中科院分区：
文献类型：
--
作者：
Malek, ZS;Pévet, P;Raison, S
血清素 (5-HT) 参与位于下丘脑 (SCN) 视交叉上核的哺乳动物生物钟的同步。该时钟通过光（光线索）和非光线索同步。非光信号主要通过中脑中缝核 (MRN) 产生的直接 5-HT 通路传递至 SCN。此外，间接投射通过 5-HT 纤维将非光输入从中脑中缝背核 (DRN) 传递到投射到 SCN 的丘脑膝间小叶 (IGL)。在大鼠中，通过原位免疫放射自显影技术研究了作为 5-HT 合成指标的色氨酸羟化酶 (TpH) 在中缝核的血清素能细胞体区域和 IGL 的血清素能末端区域中的定量分布。在 12 小时光照：12 小时黑暗（LD 12:12）下，TpH 蛋白量在 IGL 内表现出节律性变化。在白天/夜间转换时达到最高水平。在 MRN 和 DRN 的侧组中，TpH 变化与 IGL 中观察到的相反。先前在 MRN/SCN 通路中报道了这种相位相反，并且与 SCN 内 5-HT 的节律性释放相关 [Eur J Neurosci 15 (2002) 833]。因此，在 DRN-IGL 途径中观察到的 TpH 水平的每日节律性可能与夜间开始时 IGL 中 5-HT 的节律性释放相关。在持续的黑暗下，两个血清素能途径的 TpH 节律变化得以维持，并且与光/暗循环下观察到的相似。这些结果证明投射到大鼠昼夜节律系统的 5-HT 神经元中存在昼夜节律内源性功能。 (C) 2004 年国际广播组织。由爱思唯尔有限公司出版。保留所有权利。
Serotonin (5-HT) is involved in the synchronisation of the mammalian circadian clock located in the supra-chiasmatic nuclei of the hypothalamus (SCN). This clock is synchronised by light (photic cues) and by non-photic cues. Non-photic cues are notably conveyed to the SCN by a direct 5-HT pathway arising from the mesencephalic median raphe nucleus (MRN). Furthermore, an indirect projection conveys non-photic inputs by 5-HT fibres from the mesencephalic dorsal raphe nucleus (DRN) to the intergeniculate leaflets of the thalamus (IGL) which project to the SCN. In the rat, the quantitative distribution of tryptophan hydroxylase (TpH), used as an index of 5-HT synthesis, was studied by in situ immunoautoradiography in both the sero-toninergic cell bodies area of the raphe nuclei and the sero-toninergic terminal field of the IGL. Under a 12 h light: 12 h dark (LD 12:12), TpH protein amount exhibited a rhythmic variation within the IGL. The maximum levels were reached at the day/night transition. In both MRN and the lateral groups of the DRN, TpH variations were opposite to those observed in the IGL. Such phase opposition was reported previously in the MRN/SCN pathway and was correlated with a rhythmic release of 5-HT within the SCN [Eur J Neurosci 15 (2002) 833]. Thus, the daily rhythmicity of TpH levels observed in DRN-IGL pathway may be correlated with a rhythmic release of 5-HT in the IGL at the beginning of the night. Under constant darkness, TpH rhythmic variations in the two serotoninergic pathways were maintained and similar to those observed under light/dark cycle. These results demonstrate the existence of a circadian endogenous functioning in the 5-HT neurones projecting to the rat circadian system. (C) 2004 IBRO. Published by Elsevier Ltd. All rights reserved.