Pickard G E, Turek F W
Brain Res. 1983 Jun 6;268(2):201-10. doi: 10.1016/0006-8993(83)90486-9.
Unilateral lesions of the bilaterally paired suprachiasmatic nuclei of the hypothalamus were made in golden hamsters maintained in constant light (LL). Prior to surgery, the circadian rhythm of locomotor activity had dissociated or 'split' into two distinct components in 19 out of 30 hamsters, while in the remaining 11 animals (i.e. non-splitters) a normal rhythm with a single bout of activity was maintained. Following destruction of a major portion (i.e. 50-100%) of a single suprachiasmatic nucleus (SCN) in 6 'split' and 5 'non-split' hamsters, a single circadian bout of activity was observed in all animals. In 9 of these 11 animals the circadian period of the activity rhythm was altered following unilateral SCN lesions. In two split animals sustaining lesions which missed the SCN, but disrupted efferents caudal to the SCN, the split condition was also abolished. Lesions which destroyed less than 50% of a single SCN did not abolish the split condition (n = 6) and had little effect on the circadian pattern of the non-splitters (n = 5). In contrast, bilateral destruction of the suprachiasmatic nuclei eliminated the circadian pattern of activity in both 'split' (n = 5) and 'non-split' (n = 1) animals. These results demonstrate that each SCN is capable by itself of maintaining circadian rhythmicity and that at least two circadian oscillators, or oscillating systems, reside within the suprachiasmatic nuclei.
在持续光照（LL）条件下饲养的金黄仓鼠中，对双侧配对的下丘脑视交叉上核进行单侧损伤。手术前，30只仓鼠中有19只的运动活动昼夜节律已解离或“分裂”为两个不同的成分，而其余11只动物（即非分裂者）则维持着单次活动发作的正常节律。在6只“分裂”和5只“非分裂”仓鼠中，对单个视交叉上核（SCN）的大部分（即50 - 100%）进行破坏后，所有动物均观察到单次昼夜活动发作。在这11只动物中的9只中，单侧SCN损伤后活动节律的昼夜周期发生了改变。在两只分裂动物中，损伤未累及SCN，但破坏了SCN尾侧的传出神经，分裂状态也被消除。破坏单个SCN不到50%的损伤并未消除分裂状态（n = 6），对非分裂者的昼夜模式影响很小（n = 5）。相比之下，双侧破坏视交叉上核消除了“分裂”（n = 5）和“非分裂”（n = 1）动物的昼夜活动模式。这些结果表明，每个SCN自身都能够维持昼夜节律性，并且至少有两个昼夜振荡器或振荡系统存在于视交叉上核内。
