LaVinka Pamela Colleen, Brand Antje, Landau Victoria J, Wirtshafter David, Park Thomas J
University of Illinois at Chicago, Biological Sciences, 840 W Taylor St, Chicago, IL 60607, USA.
J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2009 May;195(5):419-27. doi: 10.1007/s00359-009-0420-0. Epub 2009 Feb 15.
Naked mole-rats (Heterocephalus glaber) naturally lack neuropeptides associated with the signaling of chemical irritants from C type trigeminal nerve fibers. The goal of the present study was to assess behavioral responses of these animals to stimulation of the trigeminal chemosensory system, and to determine if stimulation would increase post-synaptic activity in the trigeminal nucleus, as seen in laboratory mice and rats. The results show that naked mole-rats are behaviorally insensitive to capsaicin solution applied to the nostrils and to ammonia fumes in a behavioral avoidance test. Centrally, the number of c Fos labeled cells in the spinal trigeminal nucleus increased from exposure to ammonia although the magnitude of the increase was less than for rats. The increase observed in naked mole-rats likely reflects activity from glutamate release, which appears insufficient to drive pain and aversion behaviors. The results support the idea that neuropeptides in the C fibers of the trigeminal system may be required to signal the aversive quality of specific chemical irritants. The natural lack of neuropeptides in naked mole-rats may be an adaptation to living in a challenging subterranean environment with extremely high levels of ammonia and carbon dioxide, stimuli known to excite trigeminal chemosensory C fibers.
裸鼹鼠（Heterocephalus glaber）天然缺乏与C型三叉神经纤维化学刺激信号相关的神经肽。本研究的目的是评估这些动物对三叉化学感觉系统刺激的行为反应，并确定这种刺激是否会像在实验室小鼠和大鼠中那样增加三叉神经核的突触后活动。结果表明，在行为回避试验中，裸鼹鼠对涂抹在鼻孔的辣椒素溶液和氨气烟雾在行为上不敏感。在中枢方面，尽管增加的幅度小于大鼠，但暴露于氨气后，脊髓三叉神经核中c-Fos标记细胞的数量增加。裸鼹鼠中观察到的增加可能反映了谷氨酸释放产生的活动，而这种活动似乎不足以引发疼痛和厌恶行为。这些结果支持了这样一种观点，即三叉神经系统C纤维中的神经肽可能是特定化学刺激厌恶性质信号传递所必需的。裸鼹鼠天然缺乏神经肽可能是对生活在具有极高氨气和二氧化碳水平的具有挑战性的地下环境的一种适应，已知这些刺激会激发三叉化学感觉C纤维。
