The serotonergic projection from the median raphe nucleus to the suprachiasmatic nucleus modulates activity phase onset, but not other circadian rhythm parameters
The serotonergic projection from the median raphe nucleus to the suprachiasmatic nucleus modulates activity phase onset, but not other circadian rhythm parameters
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DOI：
10.1016/s0006-8993(97)00111-x
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发表时间：
1997-04-25
期刊：
影响因子：
2.9
通讯作者：
Morin, LP
中科院分区：
文献类型：
--
作者：
MeyerBernstein, EL;Blanchard, JH;Morin, LP
视交叉上核（SCN）由起源于中缝正中核（MR）的多巴胺能纤维密集支配。MR的5-羟色胺（5-HT）特异性病变改变了SCN以及所有其他MR受体区域中的夹带并消除了5-HT纤维。本研究使用SCN或MR的5-HT特异性病变来确定5-HT在SCN中作为夹带调节剂的作用。MR的神经毒性损伤显著减少了该核中的5-HT细胞体，并基本上消除了SCN的所有5-HT神经支配。如前所述，这些解剖学变化与活动开始提前、偏移延迟和活动相（α）扩展相关。神经毒素直接应用于SCN引起的平均活动发作的提前，但没有影响偏移或α。大约一半的SCN病变动物的发作与MR病变组相当，而其余动物的发作正常。SCN 5-HT神经支配的损失是严重的所有SCN病变的动物，但显着更大的那些先进的活动发作。这些结果表明，虽然5-HT投影到SCN可能是负责调制活动发作，活动偏移的时间似乎是由MR投影到SCN以外的区域调节。此外，令人惊讶的是，SCN中很少的5-HT纤维足以维持夹带的正常相位角。
The suprachiasmatic nucleus (SCN) is densely innervated by serotonergic fibers originating in the median raphe nucleus (MR). Serotonin (5-HT) specific lesions of the MR alter entrainment and eliminate 5 HT fibers in the SCN, as well as in all other MR-recipient areas. The present study used 5-HT specific lesions of the SCN or the MR to determine the role of 5-HT in the SCN as a regulator of entrainment. Neurotoxic lesions of the MR significantly reduced 5-HT cell bodies in that nucleus and eliminated essentially all 5-HT innervation of the SCN. As previously demonstrated, these anatomical changes were associated with an advance in activity onset, delay in offset and expansion of the activity phase (alpha). Neurotoxin directly applied to the SCN caused an advance in the average activity onset, but had no effect on offset or alpha. About half of the SCN lesion animals had onsets equivalent to the MR lesion group, whereas onsets of the remaining animals were normal. Loss of SCN 5-HT innervation was severe for all SCN lesion animals, but significantly greater for those with advanced activity onsets. These results suggest that although the 5-HT projection to the SCN is likely to be responsible for modulating activity onset, the timing of activity offset appears to be regulated by a MR projection to an area outside the SCN. Furthermore, surprisingly few 5-HT fibers in the SCN are sufficient to maintain the normal phase angle of entrainment.