(Credit: Image courtesy of Duke University Medical Center)
2012年10月27日 訊 /生物谷BIOON/ --在對觸覺研究的同時,，來自杜克大學(xué)醫(yī)學(xué)中心的研究者指出，特殊的神經(jīng)元會調(diào)節(jié)個體的感覺,，感覺神經(jīng)元以刺突為主要特定,，基于其容量,，其常常決定細(xì)胞對壓力的敏感性。研究結(jié)果是通過對果蠅幼蟲研究發(fā)現(xiàn)的,，刊登于10月25日的國際雜志Current Biology上,。該研究首次揭示了感覺神經(jīng)元的功能，并且為理解人類的慢性疼痛綜合征帶來了幫助,。
研究者W. Daniel Tracey表示,，在單一分子水平上,，感覺是我們理解的大多數(shù)的感知行為,，當(dāng)存在許多觸摸感知神經(jīng)元的時候，我們就不知道到底是哪一種神經(jīng)元在對壓力起反應(yīng),。研究者對果蠅的幼蟲進(jìn)行研究闡明了觸覺的感知,，與人類和大多數(shù)動物一樣，果蠅幼蟲也可以通過接觸來學(xué)習(xí),，感知環(huán)境,、危險以及更多活動等。
為了闡明觸覺的效應(yīng)，研究者用睫毛的頂端來刺果蠅幼蟲,，同時測定其行為反應(yīng)以及效應(yīng),。通過研究，研究者發(fā)現(xiàn)了一些特殊的感覺神經(jīng)元,，尤其是2級和3級的多重樹突狀神經(jīng)元,，對于果蠅的觸摸傳感器來說，神經(jīng)元的遺傳沉默效應(yīng)可以損傷感覺效應(yīng),。
研究者的發(fā)現(xiàn)或許為研究動物模型以更好地理解觸覺提供基礎(chǔ),，Tracey說，我們并不知道是否人類也會出現(xiàn)類似的結(jié)構(gòu),，但是未來研究中我們會對其它物種進(jìn)行觸覺感知的研究,。研究者希望更好地理解人類的觸覺可以幫助臨床醫(yī)師治療那些疼痛或者感覺缺失的病人們。
通過學(xué)習(xí)更多的觸覺感知效用,，研究者就可以解釋為何這些神經(jīng)元對于刺激變得如此敏感,，以及為何這些信號會損傷?；蛟S在未來可以幫助人們理解慢性疼痛時間的發(fā)生及其致病的分子機(jī)制,。相關(guān)研究由國家神經(jīng)性疾病和卒中研究所等機(jī)構(gòu)提供資助。（生物谷Bioon.com）
編譯自：Sensory Neurons Identified as Critical to Sense of Touch
doi:10.1016/j.cub.2012.09.019
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Dendritic Filopodia, Ripped Pocket, NOMPC, and NMDARs Contribute to the Sense of Touch in Drosophila Larvae
Asako Tsubouchi, Jason C. Caldwell, W. Daniel Tracey
Background Among the Aristotelian senses, the subcellular and molecular mechanisms involved in the sense of touch are the most poorly understood. Results We demonstrate that specialized sensory neurons, the class II and class III multidendritic (md) neurons, are gentle touch sensors of Drosophila larvae. Genetic silencing of these cells significantly impairs gentle touch responses, optogenetic activation of these cells triggers behavioral touch-like responses, and optical recordings from these neurons show that they respond to force. The class III neurons possess highly dynamic dendritic protrusions rich in F-actin. Genetic manipulations that alter actin dynamics indicate that the actin-rich protrusions (termed sensory filopodia) on the class III neurons are required for behavioral sensitivity to gentle touch. Through a genome-wide RNAi screen of ion channels, we identified Ripped Pocket (rpk), No Mechanoreceptor Potential C (nompC), and NMDA Receptors 1 and 2 (Nmdars) as playing critical roles in both behavioral responses to touch and in the formation of the actin-rich sensory filopodia. Consistent with this requirement, reporters for rpk and nompC show expression in the class III neurons. A genetic null allele of rpk confirms its critical role in touch responses. Conclusions Output from class II and class III md neurons of the Drosophila larvae is necessary and sufficient for eliciting behavioral touch responses. These cells show physiological responses to force. Ion channels in several force-sensing gene families are required for behavioral sensitivity to touch and for the formation of the actin-rich sensory filopodia.
