據(jù)國外媒體報(bào)道,，研究人員一項(xiàng)最新老鼠實(shí)驗(yàn)顯示,，大腦不依賴味覺機(jī)制便可以探測到食物中的卡路里,。這種感知系統(tǒng)被稱為“大腦第六感”,，有利于科學(xué)家對人體肥胖的更深入理解,。該研究發(fā)現(xiàn)暗示高糖易導(dǎo)致肥胖的玉米糖漿為什么受人們的喜愛并廣泛地用于食物佐料,。負(fù)責(zé)該研究的美國杜克大學(xué)研究人員伊凡·德·阿拉喬和同事們將該研究發(fā)表在3月27日出版的《神經(jīng)元》雜志上,。
在實(shí)驗(yàn)中，研究人員對老鼠基因進(jìn)行了改變使其產(chǎn)生“盲糖”反應(yīng),，使老鼠缺少能探測甜味食物的關(guān)鍵性味覺接受細(xì)胞,。接下來研究人員將正常老鼠和盲糖老鼠分成兩組觀測它們飲用含糖液和無糖甜味溶液的具體反應(yīng)，測試結(jié)果顯示,，盲糖老鼠不依賴于探測能力,，在選擇食物時(shí)更傾向于含高卡路里的糖液。
研究人員通過對盲糖老鼠大腦分析,，表明大腦對食物的感應(yīng)線路(reward circuitry)依賴于卡路里攝入量,，獨(dú)立于動物的味覺探測系統(tǒng)。分析結(jié)果顯示大腦化學(xué)多巴胺含量作為感應(yīng)線路的刺激中心隨著卡路里攝入量增加而上升,。同時(shí),，電生理學(xué)研究顯示食物感應(yīng)區(qū)域的神經(jīng)元阿肯伯氏核(nucleus accumbens)受卡路里攝入量刺激，獨(dú)立而味覺探測系統(tǒng),。
阿拉喬稱,，簡要地進(jìn)行概括，我們研究顯示前側(cè)多巴胺紋狀體(dopamine-ventral striatum)感應(yīng)系統(tǒng),，具有連接探測和分配美味食物的感應(yīng)價(jià)值,，可以在缺乏味覺接收信號情況下能夠響應(yīng)食物中的卡路里。因此,，這些大腦路徑并不排除對感觀美食誘惑影響的編碼,，但也可能表現(xiàn)包括探測腸胃和新陳代謝信息的不確定性功能,。
贊恩·安德魯斯和托馬斯·霍瓦斯在《神經(jīng)元》雜志上發(fā)表評論稱，這項(xiàng)大腦卡路里感應(yīng)系統(tǒng)的發(fā)現(xiàn),，帶給我們一些科學(xué)思考,，比如：該研究對于人體肥胖發(fā)病機(jī)理和社會現(xiàn)象的重要理解和認(rèn)識。(魏冬)
生物谷推薦原始出處：
Neuroscience Volume 120, Issue 4, 15 September 2003, Pages 1149-1156
Cholinergic interneurons of the nucleus accumbens and dorsal striatum are activated by the self-administration of cocaine
M. L. Berlangaa, C. M. Olsenb, V. Chenc, A. Ikegamib, B. E. Herringc, C. L. Duvauchellea, b, d and A. A. Alcantara, , a, c, d
a Institute for Neuroscience, The University of Texas at Austin, Austin, TX 78712, USA
b College of Pharmacy, The University of Texas at Austin, Austin, TX 78712, USA
c Department of Psychology, The University of Texas at Austin, Seay Building 4.212, Austin, TX 78712, USA
d The Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX 78712, USA
Accepted 25 April 2003. ; Available online 30 July 2003.
Abstract
The nucleus accumbens, a major component of the ventral striatum, and the dorsal striatum are primary targets of the mesolimbic dopamine pathway, which is a pathway that plays a critical role in reward and addiction. The shell compartment of the nucleus accumbens and the ventromedial striatum, in particular, receive extensive afferent projections from the ventral tegmental area, which is the major afferent source of the mesolimbic pathway [Prog Brain Res 99 (1993) 209; J Neurosci 7 (1987) 3915]. The present study focused on striatal cholinergic interneurons as potential key neurons involved in the neural basis of drug reinforcement. The main finding of this study is that cholinergic interneurons located in the shell compartment of the nucleus accumbens and the ventromedial striatum were activated, as measured by Fos labeling, following a 1 h session of the self-administration of cocaine in rats. A direct correlation existed between the percent of cholinergic interneurons that were activated and the amount of cocaine that was self-administered. The greatest amount of administered cocaine (approximately 10 mg/kg) resulted in the activation of approximately 80% of the cholinergic neurons. No such correlation existed in the group of animals that self-administered saline. In addition, activation was not found in the core compartment of the nucleus accumbens or the dorsolateral striatum, which receive extensive innervation from the substantia nigra and thus are more closely tied to the motor effects of the drug.
In conclusion, cocaine-driven neuronal activation was specific to the shell compartment of the nucleus accumbens (R2=0.9365) and the ventromedial striatum (R2=0.9059). These findings demonstrate that cholinergic interneurons are involved in the initial stage of cocaine intake and that these neurons are located in areas of the nucleus accumbens and dorsal striatum that are more closely tied to the rewarding and hedonic effects rather than the motor effects of cocaine intake.
