Harrington M E, Eskes G A, Dickson P, Rusak B
Department of Psychology, Dalhousie University, Halifax, Canada.
Brain Res Bull. 1990 Apr;24(4):593-7. doi: 10.1016/0361-9230(90)90164-u.
Constant light exposure (LL) can result in "splitting" of circadian rhythms into two components coupled about 12 hr apart. Splitting has been interpreted as evidence for the presence of two main oscillators or groups of oscillators underlying circadian rhythms. Abolition of splitting after unilateral suprachiasmatic nucleus ablation suggested that each suprachiasmatic nucleus could correspond to one of these component oscillators. We examined whether lesions outside the suprachiasmatic nuclei (SCN) would abolish split activity rhythms of hamsters in LL. Wheel-running activity was recorded for 3 months after surgery. Tissue damage was assessed by Klüver-Barrera staining. Damage to areas dorso-caudal to the SCN was able to abolish the split condition. Bilateral damage to the anterior SCN, partial unilateral SCN ablation or unilateral periventricular damage also abolished the split pattern. These results indicate that destruction of one SCN is not essential for the elimination of split rhythms since lesions dorsal to the SCN or partial bilateral SCN damage are also effective. Indirect lesion effects on SCN function or damage to extra-SCN oscillators may account for the loss of the split condition.
持续光照（LL）可导致昼夜节律“分裂”为两个大约相隔12小时耦合的成分。这种分裂被解释为昼夜节律存在两个主要振荡器或振荡器组的证据。单侧视交叉上核切除后分裂现象的消失表明，每个视交叉上核可能对应于这些成分振荡器之一。我们研究了视交叉上核（SCN）以外的损伤是否会消除LL条件下仓鼠的分裂活动节律。术后记录3个月的转轮活动。通过Klüver-Barrera染色评估组织损伤。SCN背尾侧区域的损伤能够消除分裂状态。双侧前SCN损伤、部分单侧SCN切除或单侧脑室周围损伤也消除了分裂模式。这些结果表明，破坏一个SCN对于消除分裂节律并非必不可少，因为SCN背侧损伤或部分双侧SCN损伤也有效。对SCN功能的间接损伤效应或SCN外振荡器的损伤可能是分裂状态消失的原因。
