Suprachiasmatic Nucleus and Subparaventricular Zone Lesions Disrupt Circadian Rhythmicity but Not Light-Induced Masking Behavior in Nile Grass Rats
Suprachiasmatic Nucleus and Subparaventricular Zone Lesions Disrupt Circadian Rhythmicity but Not Light-Induced Masking Behavior in Nile Grass Rats
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DOI：
10.1177/0748730415626251
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发表时间：
2016-04-01
影响因子：
3.5
通讯作者：
Smale, Laura
中科院分区：
文献类型：
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作者：
Gall, Andrew J.;Shuboni, Dorela D.;Smale, Laura
腹侧室旁区(VSPVZ)接受视网膜的直接输入，影响啮齿类动物的日常活动模式，使其有可能参与调节对光的急性行为反应(即掩蔽)。用谷氨酸激动剂N-甲基-D，L-天冬氨酸对日间草鼠(Arvicanthis Niloticus)的vSPVZ进行化学毁损。在损毁NMA后，我们将草鼠置于不同的光照条件下(例如，12：12明暗、恒定暗、恒定光照)；在昼夜时间(CT)6、14、18和22呈现一系列光脉冲；并将它们置于7h超常周期中以评估行为掩蔽。广泛的双侧vSPVZ损伤扰乱了活动的昼夜节律的表达，取消了对光的掩蔽反应的昼夜调制，而不影响光诱导的掩蔽行为本身。我们还发现，在白天活动的草鼠中，NMA不仅能破坏vSPVZ的神经元，而且还能破坏视交叉上核(SCN)的神经元，尽管兴奋性毒素对夜间活动的啮齿类动物的SCN内的细胞没有作用。草鼠SCN对NMA毒性的脆弱性增加了夜间和白天活动物种谷氨酸受体密度差异的可能性。在损伤延伸到SCN的情况下，存在对光的掩蔽反应，与损伤仅限于vSPVZ的动物所表现的反应相似。因此，广泛的双侧SCN和vSPVZ损伤扰乱了昼夜节律的表达，而不影响一个物种对光的急性反应。我们目前和以前的结果表明，除SCN或vSPVZ以外的视网膜早发型脑区，如膝间小叶或橄榄顶盖前核，可能负责调节白天草鼠对光的掩蔽反应。
The ventral subparaventricular zone (vSPVZ) receives direct retinal input and influences the daily patterning of activity in rodents, making it a likely candidate for the mediation of acute behavioral responses to light (i.e., masking). We performed chemical lesions aimed at the vSPVZ of diurnal grass rats (Arvicanthis niloticus) using N-methyl-D,L-aspartic acid (NMA), a glutamate agonist. Following NMA lesions, we placed grass rats in various lighting conditions (e.g., 12:12 light-dark, constant dark, constant light); presented a series of light pulses at circadian times (CT) 6, 14, 18, and 22; and placed them in a 7-h ultradian cycle to assess behavioral masking. Extensive bilateral lesions of the vSPVZ disrupted the expression of circadian rhythms of activity and abolished the circadian modulation of masking responses to light, without affecting light-induced masking behavior per se. We also found that in diurnal grass rats, NMA was capable of destroying not only neurons of the vSPVZ but also those of the suprachiasmatic nucleus (SCN), even though excitotoxins have been ineffective at destroying cells within the SCN of nocturnal rodents. The vulnerability of the grass rat's SCN to NMA toxicity raises the possibility of a difference in density of receptors for glutamate between nocturnal and diurnal species. In cases in which damage extended to the SCN, masking responses to light were present and similar to those displayed by animals with damage restricted to the vSPVZ. Thus, extensive bilateral lesions of the SCN and vSPVZ disrupted the expression of circadian rhythms without affecting acute responses to light in a diurnal species. Our present and previous results suggest that retinorecipient brain areas other than the SCN or vSPVZ, such as the intergeniculate leaflet or olivary pretectal nucleus, may be responsible for the mediation of masking responses to light in the diurnal grass rat.