The serotonergic projection from the median raphe nucleus to the suprachiasmatic nucleus modulates activity phase onset, but not other circadian rhythm parameters

被引:53
作者
MeyerBernstein, EL
Blanchard, JH
Morin, LP
机构
[1] SUNY STONY BROOK,GRAD PROGRAM NEUROBIOL & BEHAV,STONY BROOK,NY 11794
[2] SUNY STONY BROOK,DEPT PSYCHIAT & BEHAV SCI,STONY BROOK,NY 11794
关键词
suprachiasmatic nucleus; median raphe; circadian rhythm; serotonin; locomotor activity; entrainment;
D O I
10.1016/S0006-8993(97)00111-X
中图分类号
Q189 [神经科学];
学科分类号
071006 ;
摘要
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.
引用
收藏
页码:112 / 120
页数:9
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