Nerve-target interactions in the gustatory system following unilateral chorda tympani nerve section.
Nerve-target interactions in the gustatory system following unilateral chorda tympani nerve section.
复制标题
单侧鼓索神经切片后味觉系统中的神经-目标相互作用。
DOI：
10.1093/chemse/bjh115
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发表时间：
2005
期刊：
影响因子：
3.5
通讯作者：
Hill,DavidL
中科院分区：
文献类型：
--
作者：
Hill,DavidL
Although much effort has been directed at examining the morphological characteristics of denervated and regenerated taste buds, relatively little is known about the physiology of reinnervated taste cells (Vintschgau and Hönigschmied, 1876; Guth, 1957; Fujimoto and Murray, 1970; Cheal and Oakley, 1977; Whitehead et al., 1987). Over 25 years ago, Oakley (Cheal et al., 1977) and colleagues found that some chorda tympani fibers reinnervated fungiform papillae on the gerbil’s anterior tongue in< 2 weeks post-sectioning. Studies that examined recovery of taste function following nerve damage (Cain et al., 1996; Cheal et al., 1977; Ninomiya, 1998; Yasumatsu et al., 2003) indicate that regenerated taste nerves generally recover normal function after progressing through a transitional period. Only relatively recently has the impact of environment on the adult regenerating taste system been explored.Regenerating taste receptor cells in adult rats are susceptible to dietary influences (Hill and Phillips, 1994). Sectioning the chorda tympani unilaterally in rats fed a sodium-restricted diet at adulthood resulted in a regenerated nerve that had attenuated responses to sodium salts. Responses to other stimuli were unaffected. In addition, there were other, novel effects. In the same rat, the contralateral, uncut nerve was supersensitive to sodium salts. The supersensitivity developed progressively following an initial subnormal response. Moreover, these remarkable changes happened in the absence of reinnervation. Although the mechanism underlying these large, dynamic functional changes are not clearly identified, increasing evidence suggests a novel and important interaction exists with the immune system (Phillips and Hill, 1996; Hendricks et al., 2002; McCluskey and Hill, 2002; McCluskey, 2003). We hypothesize that the immune system may be activated during phagocytosis of neural and taste receptor cell debris following nerve section in sodium-replete rats. The activated immune cells may then play a role in maintaining normal function. We further hypothesized, from published reports (Chandra and Dayton, 1982; Pimentel and Cook, 1987; Latshaw, 1991), that sodium-restricted rats are immunocompromised and may fail to maintain normal taste function on the intact side of the tongue following unilateral nerve section. In summary, there is emerging evidence that the immune system has a significant role in the biology of adult taste buds and may be similar to roles demonstrated in other sensory receptors (Warchol, 1997; Warchol, 1999; Warchol et al., 2001). In addition to providing an excellent model for functional studies of taste receptor cell plasticity, the regenerating taste system provides an excellent model in which to study the plasticity of gustatory neuron/target matching. We explored the hypothesis that the altered taste function produced by combining unilateral chorda tympani nerve section with sodium restriction in adult rats also produces alterations in peripheral innervation (Shuler et al., 2004). For both sodium-restricted and sodium-replete rats, section-induced morphological alterations occurred on both the regenerated and the intact side of the tongue. Namely, fewer than normal numbers of geniculate ganglion neurons per taste bud volume innervated single fungiform papillae on the regenerated side, and greater than normal numbers of
