柯鈺婷,周文華,2
(1.寧波大學(xué)醫(yī)學(xué)院,浙江寧波315211;2.寧波戒毒研究中心,浙江寧波315000)
運(yùn)動干預(yù)藥物依賴的神經(jīng)生物學(xué)機(jī)制研究進(jìn)展
柯鈺婷1,周文華1,2
(1.寧波大學(xué)醫(yī)學(xué)院,浙江寧波315211;2.寧波戒毒研究中心,浙江寧波315000)
流行病學(xué)研究證實,有規(guī)律的有氧運(yùn)動能降低藥物濫用的可能性?;A(chǔ)和臨床研究顯示,運(yùn)動可作為藥物依賴的一種潛在的干預(yù)手段,在成癮依賴的各個階段產(chǎn)生有益和持久的保護(hù)作用。運(yùn)動的這種保護(hù)作用與其調(diào)節(jié)藥物依賴相關(guān)的神經(jīng)適應(yīng)性改變有關(guān)。運(yùn)動可調(diào)節(jié)各種神經(jīng)遞質(zhì)系統(tǒng)以及細(xì)胞內(nèi)信號傳遞,增加腦源性神經(jīng)營養(yǎng)因子水平,促進(jìn)神經(jīng)再生和膠質(zhì)細(xì)胞再生和調(diào)控表觀遺傳學(xué)變化等提升大腦對成癮物質(zhì)損害的抵抗力,降低大腦對藥物的渴求感,預(yù)防復(fù)吸。此外,運(yùn)動的強(qiáng)度、時間和類型不同也會產(chǎn)生不同的神經(jīng)生物學(xué)機(jī)制。本文著重從運(yùn)動干預(yù)藥物依賴的神經(jīng)生物學(xué)機(jī)制方面綜述了以運(yùn)動為基礎(chǔ)的單獨(dú)或輔助其他治療手段干預(yù)藥物成癮。
運(yùn)動;物質(zhì)相關(guān)性障礙;神經(jīng)可塑性
藥物依賴是一種表現(xiàn)為持續(xù)性渴求和強(qiáng)迫性覓藥行為的慢性復(fù)發(fā)性腦病[1]。目前治療阿片類藥物依賴的方式主要有藥物治療(如美沙酮和丁丙諾啡替代療法)和非藥物治療(如行為和心理矯正)等[2]。豐富環(huán)境(enriched environment,EE)作為一種可選擇的非藥物強(qiáng)化方式用以消除覓藥行為并減少復(fù)吸風(fēng)險[3]。運(yùn)動作為EE的一個重要手段,對藥物成癮的各個階段包括起始階段、維持階段、戒斷階段以及復(fù)吸過程均有保護(hù)作用,運(yùn)動對預(yù)防藥物成癮和復(fù)吸也有積極的作用?;A(chǔ)和臨床研究表明,經(jīng)過≥6周中等強(qiáng)度運(yùn)動能降低起始和維持階段的藥物攝入量和獎賞動機(jī)[4-5],戒斷階段進(jìn)行>12周中等強(qiáng)度運(yùn)動能減少戒斷癥狀和覓藥行為[6-7],減輕抑郁和焦慮等負(fù)性情緒[8-9],預(yù)防復(fù)吸,治療藥物依賴[10]。此外,運(yùn)動還具有長時程治療效應(yīng),其對復(fù)吸行為影響的作用持續(xù)時間超過了運(yùn)動的時間[11]。因此,運(yùn)動可作為一種潛在的干預(yù)手段預(yù)防和治療藥物依賴。運(yùn)動的這種保護(hù)作用與其調(diào)節(jié)藥物依賴相關(guān)的神經(jīng)適應(yīng)性改變有關(guān)。長期濫用藥物會使大腦產(chǎn)生適應(yīng)性改變,主要表現(xiàn)為腦內(nèi)多巴胺(dopamine,DA)、谷氨酸、阿片肽和γ-氨基丁酸(γ-aminobutyric acid,GABA)能等與獎賞系統(tǒng)有關(guān)的神經(jīng)遞質(zhì)改變,一些腦區(qū)的突觸可塑性、神經(jīng)再生和神經(jīng)營養(yǎng)因子釋放的改變等。藥物的長期濫用還會通過神經(jīng)元染色體重塑的方式使基因表達(dá)發(fā)生變化[12]。近來認(rèn)為,表觀遺傳調(diào)控介導(dǎo)的基因長時程表達(dá)改變可能是藥物成癮的這種穩(wěn)定的行為異常模式的機(jī)制之一[13]。運(yùn)動能通過多種作用機(jī)制協(xié)助藥物濫用者擺脫毒癮,其能調(diào)節(jié)各種神經(jīng)遞質(zhì)系統(tǒng)以及細(xì)胞內(nèi)信號傳遞,增加腦源性神經(jīng)營養(yǎng)因子(brain-derived neurotrophic factor,BDNF)水平,促進(jìn)神經(jīng)再生和膠質(zhì)細(xì)胞再生和調(diào)控表觀遺傳學(xué)變化等提升大腦對成癮物質(zhì)損害的抵抗力,降低大腦對藥物的渴求感,預(yù)防復(fù)吸。本文主要就運(yùn)動對藥物依賴的神經(jīng)可塑性機(jī)制和調(diào)節(jié)進(jìn)行闡述,揭示運(yùn)動干預(yù)藥物依賴的神經(jīng)生物學(xué)機(jī)制,為藥物依賴治療提供新的理論構(gòu)架。
運(yùn)動具有正性強(qiáng)化作用,它所影響的與介導(dǎo)藥物正性強(qiáng)化的信號分子和神經(jīng)解剖結(jié)構(gòu)類似,這可能是運(yùn)動干預(yù)藥物依賴有效性的神經(jīng)機(jī)制之一。長時程和短時程運(yùn)動都會導(dǎo)致神經(jīng)遞質(zhì)的改變,如強(qiáng)迫和自愿運(yùn)動會改變?nèi)ゼ啄I上腺素(noradrenaline,NA)、5-羥色胺(5-hydroxytryptamine,5-HT)、GABA和內(nèi)源性大麻素的濃度。所有這些遞質(zhì)在成癮的形成和發(fā)展中都起著重要的作用。
1.1 運(yùn)動對多巴胺、5-羥色胺和去甲腎上腺素的影響
DA是主要的兒茶酚胺類遞質(zhì),由腦內(nèi)分泌,直接影響情緒、感覺和欣快感。中腦邊緣和中腦皮質(zhì)的DA能系統(tǒng)是藥物產(chǎn)生獎賞效應(yīng)的主要部位,在藥物成癮中有重要作用[14]。而長期濫用藥物會導(dǎo)致中腦邊緣功能減退,內(nèi)源性DA釋放減少,機(jī)體只能通過促進(jìn)吸食藥物來彌補(bǔ)DA缺失所造成的快感缺乏等[15]。近年來研究發(fā)現(xiàn),不同水平的運(yùn)動能影響DA能系統(tǒng)信號傳遞,增加DA的釋放。Goekint等[16]發(fā)現(xiàn),2 h的快速運(yùn)動(如跑步)能誘導(dǎo)海馬DA釋放,其釋放量是靜止組大鼠的2倍。長期自愿和強(qiáng)迫運(yùn)動能增加腦內(nèi)酪氨酸羥化酶(DA合成過程中的限速酶)和DA受體偶聯(lián)蛋白表達(dá),促進(jìn)DA的合成[17]。尤其是自愿運(yùn)動能激活中腦腹側(cè)被蓋區(qū)的DA能神經(jīng)元[18],增加伏隔核(nucleus accumbens,NAc)DA濃度[19]。而藥物濫用所產(chǎn)生的正性強(qiáng)化作用部分是通過增加NAc DA濃度介導(dǎo)的[20]。
長期吸毒會使DA系統(tǒng)產(chǎn)生神經(jīng)適應(yīng)性改變,如上調(diào)D1樣受體,下調(diào)D2樣受體,敏化長期戒斷后的DA系統(tǒng)信號通路[21]。運(yùn)動能調(diào)節(jié)藥物誘發(fā)的神經(jīng)適應(yīng)性,改變個體對藥物的易感性,減少復(fù)吸。例如,緩慢運(yùn)動不僅降低了去氧麻黃堿(甲基苯丙胺)誘導(dǎo)的覓藥行為,還減少了杏仁核和紋狀體中因藥物刺激誘導(dǎo)的DA釋放[22]。O′Dell等[23]發(fā)現(xiàn),運(yùn)動能減弱甲基苯丙胺誘導(dǎo)的紋狀體DA能損傷以及5-HT能神經(jīng)元損傷。另外,強(qiáng)迫和自愿運(yùn)動不僅能增加正常動物的DA水平,還能使患有某些特定疾病(高血壓、癲癇等)所致的DA水平過低的動物恢復(fù)正常甚至增加[24]。值得注意的是,運(yùn)動條件不同會產(chǎn)生不同的神經(jīng)生物學(xué)效應(yīng)。Greenwood等[17]研究發(fā)現(xiàn),長期高水平自愿運(yùn)動會使獎賞通路產(chǎn)生神經(jīng)適應(yīng)性改變,這些改變與長期濫用藥物后產(chǎn)生的效應(yīng)類似。這些發(fā)現(xiàn)說明運(yùn)動能使長期用藥后的中腦邊緣的功能減退正?;?。
5-HT主要在增加成癮易感性特征的情感和認(rèn)知(如抑郁、強(qiáng)迫等)系統(tǒng)中發(fā)揮作用[25]。NA主要涉及大腦覺醒、認(rèn)知、應(yīng)激和情感等方面的功能[26]。兩者均在藥物成癮和戒斷后藥物復(fù)吸中有關(guān)鍵作用。Valim等[27]隨機(jī)平行試驗發(fā)現(xiàn),有氧訓(xùn)練會增加血清中5-HT水平,有利于緩解長期吸毒后戒斷時期的抑郁等負(fù)性情感狀態(tài)。在動物模型中,NA對應(yīng)激誘導(dǎo)的和可卡因誘導(dǎo)的復(fù)吸有重要的作用。如Soares等[28]發(fā)現(xiàn),運(yùn)動訓(xùn)練能減少前額皮質(zhì)(prefrontal cortex,PFC)NA的釋放,減弱應(yīng)激和可卡因誘導(dǎo)的復(fù)吸行為。
總之,在長期吸毒的DA系統(tǒng)信號傳遞中,運(yùn)動通過與藥物類似的作用增加DA的濃度和DA受體偶聯(lián)蛋白的表達(dá),激活獎賞通路,拮抗藥物引起的神經(jīng)適應(yīng)性改變,起到保護(hù)藥物依賴人群和減少其復(fù)吸的作用。
1.2 運(yùn)動對谷氨酸的影響
谷氨酸是中樞神經(jīng)系統(tǒng)內(nèi)廣泛分布的、重要的興奮性氨基酸類神經(jīng)遞質(zhì),谷氨酸及其受體參與了阿片軀體及精神依賴、條件化行為的形成[29]。N-甲基-D-天門冬氨酸受體是一個離子通道偶聯(lián)的大分子復(fù)合體,具有谷氨酸、甘氨酸和多氨類等多種配體的結(jié)合位點,其功能受多種內(nèi)源性物質(zhì)及藥物的精細(xì)調(diào)節(jié),在神經(jīng)可塑性方面具有重要作用[30]。研究表明,長期使用成癮藥物會使谷氨酸內(nèi)環(huán)境穩(wěn)態(tài)失調(diào),下調(diào)膠質(zhì)細(xì)胞谷氨酸轉(zhuǎn)運(yùn)體水平,增加對藥物相關(guān)刺激的敏感性,使突觸谷氨酸釋放增加[31]。谷氨酸能系統(tǒng)信號傳遞改變對長期用藥后的覓藥行為和復(fù)吸具有重要的作用。運(yùn)動能使機(jī)體谷氨酸水平恢復(fù)正常,保護(hù)對抗長期吸毒后藥物對谷氨酸受體的過度刺激。Guezennec等[32]給予大鼠6周的強(qiáng)迫運(yùn)動后,與對照組一起進(jìn)行疲勞測試,結(jié)果發(fā)現(xiàn),運(yùn)動組谷氨酸濃度明顯減少。Biedermann等[33]用核磁共振技術(shù)觀察到自愿運(yùn)動大鼠海馬體積增加,伴隨著海馬區(qū)谷氨酸水平降低。Real等[34]則研究顯示,強(qiáng)迫跑步機(jī)運(yùn)動能增加紋狀體代謝型谷氨酸受體2/3基因的表達(dá),促進(jìn)谷氨酸受體突觸可塑性改變,抑制谷氨酸能系統(tǒng)信號傳導(dǎo),降低藥物易感性。
總之,運(yùn)動能使谷氨酸恢復(fù)到正常水平,對抗長期濫用藥物后對谷氨酸受體的過度刺激,改善機(jī)體功能,降低藥物易感性,減少復(fù)吸。
1.3 運(yùn)動對內(nèi)源性阿片肽的影響
內(nèi)源性阿片肽是存在于體內(nèi)的具有阿片樣作用的多肽,主要有腦啡肽、內(nèi)啡肽和強(qiáng)啡肽3類,它們分別作用于阿片受體亞型mu(μ),kappa(κ)和delta(δ),與情緒改變,痛覺感知和執(zhí)行能力有關(guān)。強(qiáng)迫和自愿運(yùn)動能增加血漿3類內(nèi)源性阿片肽的濃度。Malinowski等[35]對在進(jìn)行跑步機(jī)運(yùn)動前、中、后的14匹馬的血漿β-內(nèi)啡肽濃度進(jìn)行了測量,結(jié)果發(fā)現(xiàn),鍛煉后血漿β-內(nèi)啡肽濃度顯著增加。Debruille等[36]在給雌大鼠進(jìn)行3周電動跑步機(jī)訓(xùn)練后,證實了大鼠血清中總的阿片樣物質(zhì)(腦啡肽、內(nèi)啡肽和強(qiáng)啡肽)增多。長期運(yùn)動還能使阿片受體結(jié)合蛋白產(chǎn)生適應(yīng)性改變,降低對外部阿片受體激動劑的敏感性[37]。Lett等[38]發(fā)現(xiàn),自愿轉(zhuǎn)輪運(yùn)動產(chǎn)生的正性情感狀態(tài)可被阿片受體拮抗劑納洛酮阻滯,說明運(yùn)動對藥物依賴的有益效應(yīng)可能是通過阿片受體介導(dǎo)的。Mello和Walker等[39-40]通過有氧運(yùn)動研究證實,阿片受體在可卡因和乙醇的強(qiáng)化過程中起著重要的調(diào)節(jié)作用,而運(yùn)動能使過度攝入藥物時期的內(nèi)源性阿片肽系統(tǒng)正?;4送?,轉(zhuǎn)輪運(yùn)動還能減少嗎啡戒斷時的行為表現(xiàn),其機(jī)制可能是通過增加內(nèi)源性阿片肽的釋放[41]。運(yùn)動釋放內(nèi)源性阿片肽能持續(xù)很長時間。Hoffmann等[42]發(fā)現(xiàn),讓訓(xùn)練有素的大鼠進(jìn)行單期轉(zhuǎn)輪運(yùn)動后,腦脊液β-內(nèi)啡肽濃度一直升高直到48 h之后。
運(yùn)動訓(xùn)練能代替藥物釋放內(nèi)源性阿片肽,與美沙酮和其他減少藥物使用的激動劑替代療法機(jī)制一樣,以非藥理學(xué)方法阻止復(fù)吸,對藥物成癮者產(chǎn)生保護(hù)作用。
神經(jīng)可塑性包括神經(jīng)系統(tǒng)結(jié)構(gòu)與功能的可塑性,宏觀上表現(xiàn)為腦功能(如學(xué)習(xí)及記憶功能)、行為及精神活動改變;微觀上則表現(xiàn)為神經(jīng)元突觸、神經(jīng)環(huán)路超微結(jié)構(gòu)與功能的改變,包括神經(jīng)化學(xué)、神經(jīng)電生理,如長時程增強(qiáng)(long-term depression,LTD)和長時程抑制(long-term depression,LTD)等變化[43]。成癮性藥物會導(dǎo)致神經(jīng)元可塑性和適應(yīng)性改變,其長時程效應(yīng)是造成成癮者心理渴求和復(fù)吸行為的主要原因。運(yùn)動同樣能影響大腦獎賞系統(tǒng),對神經(jīng)遞質(zhì)、突觸可塑性、細(xì)胞內(nèi)信號傳遞、神經(jīng)營養(yǎng)素、神經(jīng)再生和表觀遺傳等產(chǎn)生有益作用。
2.1 運(yùn)動與突觸可塑性
1.提前聯(lián)系。2月底就要開始聯(lián)系苗種繁殖場,市場上的蝦苗很多是轉(zhuǎn)手貨,轉(zhuǎn)運(yùn)時間過長,死亡率較高,一些蝦苗即使買的時候存活,投放后不久也會死亡,建議養(yǎng)殖戶在條件允許的情況下直接到養(yǎng)殖基地購買。
突觸可塑性是指突觸在形態(tài)結(jié)構(gòu)和功能上的變動性和可修飾性,包括形態(tài)結(jié)構(gòu)和功能的可塑性[44]。突觸可塑性有多種形式,包括經(jīng)典的LTP與LTD,已被廣泛研究且普遍認(rèn)為是學(xué)習(xí)與記憶的重要機(jī)制[45]。
突觸可塑性易受突觸前遞質(zhì)釋放量和突觸后受體數(shù)目和電導(dǎo)變化等因素影響。運(yùn)動能促進(jìn)海馬區(qū)(學(xué)習(xí)記憶的關(guān)鍵部位)突觸可塑性形態(tài)結(jié)構(gòu)的形成。早期報道的運(yùn)動對大腦的作用,證明了其能導(dǎo)致大腦解剖學(xué)結(jié)構(gòu)的改變,例如增加大腦的質(zhì)量和尺寸,以及區(qū)域性地增大皮質(zhì)尺寸。隨后的分析研究也顯示出了其能導(dǎo)致一些神經(jīng)形態(tài)學(xué)改變,如能增加樹突長度和樹突棘密度,增加樹突嵴樹狀分枝,擴(kuò)增神經(jīng)前體細(xì)胞,更新海馬區(qū)齒狀回神經(jīng)再生[46]。而以上這些形態(tài)學(xué)變化普遍被認(rèn)為是儲存記憶的機(jī)制,因此,運(yùn)動可能誘導(dǎo)改善海馬的形態(tài)和功能。此外,運(yùn)動還能增強(qiáng)海馬區(qū)的LTP。Farmer等[47]取自海馬區(qū)齒狀回組織切片顯示,與靜止不動的大鼠相比,運(yùn)動的大鼠,無論是強(qiáng)迫跑步機(jī)訓(xùn)練還是滾輪訓(xùn)練都能增強(qiáng)海馬齒狀回區(qū)域的LTP,降低LTD的出現(xiàn)閾值并延長LTD。而突觸強(qiáng)度改變被認(rèn)為是哺乳動物大腦對學(xué)習(xí)和記憶適應(yīng)過程的潛在機(jī)制之一。有趣的是,相似的修飾性作用也發(fā)生在長期藥物暴露之后[48]。盡管目前運(yùn)動對成癮動物或人的突觸可塑性研究非常少,運(yùn)動也可能改善成癮者的突觸可塑性。
2.2 運(yùn)動與細(xì)胞內(nèi)信號分子
PFC的神經(jīng)元活動可能與藥物覓求行為相關(guān)[49]。磷酸化細(xì)胞外信號調(diào)節(jié)蛋白激酶(phospho-extracellular signal-regulated kinase,pERK)位于PFC中,是神經(jīng)元信號傳遞的一個標(biāo)志物,需要同時激活DA和谷氨酸信號通路才能使ERK磷酸化。ERK分子是一個涉及藥物強(qiáng)化作用的細(xì)胞內(nèi)信號分子。有關(guān)研究表明,藥物戒斷后的覓藥行為與PFC中的pERK呈正相關(guān),降低PFC中的pERK水平會使可卡因覓藥行為減少[50]。而Lynch等[11]研究發(fā)現(xiàn),在早期戒斷期給大鼠進(jìn)行轉(zhuǎn)輪運(yùn)動,不僅阻礙了一段時間戒斷后ERK磷酸化水平的升高,還減少了隨后的可卡因覓藥行為和藥物引起的神經(jīng)適應(yīng)性改變,抑制了環(huán)境線索誘導(dǎo)的復(fù)吸行為。此外,運(yùn)動還調(diào)控DA和cAMP調(diào)節(jié)的磷蛋白(蛋白激酶A抑制劑),一個對藥物產(chǎn)生強(qiáng)化作用至關(guān)重要的蛋白激酶A靶點,影響多巴胺D1受體介導(dǎo)的cAMP-蛋白激酶A信號通路,抑制蛋白激酶A,減少藥物攝入和覓藥行為[51]。
總之,運(yùn)動能通過調(diào)節(jié)一些細(xì)胞內(nèi)信號分子活性消除頑固的覓藥行為模式,降低復(fù)吸易感性,治療藥物成癮。
大腦是少數(shù)幾個不能再生的器官之一,但成年期也能形成新的神經(jīng)元,海馬區(qū)齒狀回的顆粒下層和側(cè)腦室的室管膜下層是新神經(jīng)元形成的兩個主要區(qū)域[52]。最近研究顯示,藥物成癮對神經(jīng)再生有影響。Arguello等[53]報道,長期濫用藥物會損害成年大鼠海馬區(qū)的神經(jīng)再生。而Noonan等[54]發(fā)現(xiàn),海馬區(qū)神經(jīng)再生的減少會增加可卡因自身給藥行為,抑制可卡因的消退,增加線索誘導(dǎo)的復(fù)吸。運(yùn)動能增加海馬區(qū)的神經(jīng)再生,是其調(diào)節(jié)藥物自身給藥和覓藥行為的機(jī)制之一[55]。有氧運(yùn)動能誘導(dǎo)海馬許多區(qū)域的神經(jīng)再生,而海馬神經(jīng)再生的減少與藥物攝入有關(guān)[56]。此外,有氧運(yùn)動還能增加大鼠PFC中神經(jīng)膠質(zhì)細(xì)胞再生,對藥物依賴行為有積極作用[57]。而PFC功能不足已被證明在藥物成癮的許多過渡階段有作用,對覓藥行為和戒斷后的復(fù)吸行為也有作用[58]。運(yùn)動通過增強(qiáng)海馬區(qū)神經(jīng)再生和PFC膠質(zhì)細(xì)胞再生緩沖對抗適應(yīng)藥物濫用的不良模式。
2.4 運(yùn)動與表觀遺傳調(diào)控
表觀遺傳調(diào)控包括DNA甲基化、組蛋白修飾、染色質(zhì)重塑和非編碼RNA調(diào)控,所有這些修飾都會導(dǎo)致基因激活或者沉默,影響基因轉(zhuǎn)錄,改變基因誘導(dǎo)的轉(zhuǎn)錄復(fù)合物的形成,但沒有改變基因的編碼序列[59]。目前對藥物成癮的大量研究表明,這些表觀遺傳學(xué)改變可能是導(dǎo)致藥物成癮這種穩(wěn)定的不正常行為的機(jī)制之一[60]。
運(yùn)動能通過染色體重塑、改變基因表達(dá)等表觀遺傳調(diào)控方式對藥物成癮者產(chǎn)生長時程保護(hù)作用,抑制覓藥行為,減少復(fù)吸,并可作為輔助治療手段增加治療效果。Takizawa等[61]報道,運(yùn)動能產(chǎn)生分子水平的染色質(zhì)結(jié)構(gòu)適應(yīng)性改變,降低個體藥物濫用易感性,抑制覓藥行為。Zlebnik等[62]發(fā)現(xiàn),自愿轉(zhuǎn)輪運(yùn)動會使NAc、紋狀體、內(nèi)側(cè)PFC(medial PFC,mPFC)和眶額葉皮質(zhì)中c-fos基因表達(dá)減少(功能活性的一個標(biāo)志物),降低藥物濫用易感性。此外,自愿轉(zhuǎn)輪運(yùn)動還能使PFC中BDNF啟動子Ⅳ區(qū)域的組蛋白H3乙?;?,并減少DNA甲基化,增加BDNF基因的表達(dá)[63]。這一作用能抵消因戒斷早期BDNF基因表達(dá)減少而在戒斷后期負(fù)反饋增加的BDNF基因表達(dá)效應(yīng),降低藥物對興奮性突觸的敏化作用,減少覓藥行為和復(fù)吸[64]。
2.5 運(yùn)動與神經(jīng)營養(yǎng)因子
運(yùn)動有利于大腦健康,改善認(rèn)知功能,其機(jī)制可能與增加BDNF有關(guān)[65]。BDNF是調(diào)節(jié)神經(jīng)可塑性的一個關(guān)鍵因子,能誘導(dǎo)成年海馬神經(jīng)再生、突觸再生和突觸可塑性形成,影響精神疾病和認(rèn)知功能,并被認(rèn)為是反復(fù)引起復(fù)吸行為的因素之一[66]。Lu等[67-68]將BDNF注入腦腹側(cè)被蓋區(qū)、NAc和PFC后,發(fā)現(xiàn)對大鼠覓藥行為有很大的影響,據(jù)此推斷BDNF參與戒斷后藥物引燃的復(fù)吸。此外,BDNF基因及其相關(guān)的表觀遺傳調(diào)控產(chǎn)物還與藥物濫用易感性有關(guān)[69]。Vassoler等[70]給雄鼠進(jìn)行一段時間的可卡因自身給藥后,發(fā)現(xiàn)它們能把可卡因持久表型遺傳給其雄性后代,增加其mPFC中BDNF啟動子Ⅳ區(qū)域的H3組蛋白乙?;蛊鋼碛懈偷目煽ㄒ蜃陨斫o藥起始獲得率。
最近研究表明,運(yùn)動能調(diào)節(jié)人類和動物的大腦BDNF基因轉(zhuǎn)錄,阻礙藥物誘導(dǎo)的染色體結(jié)構(gòu)改變,增加BDNF表達(dá),減少覓藥行為。Zoladz等[71]報道,運(yùn)動通過表觀遺傳調(diào)控包含BDNF基因的染色體而增加血清BDNF水平,提高骨骼肌BDNF基因表達(dá),而此BDNF基因與藥物易感性相關(guān)。另外,運(yùn)動還能使反復(fù)用藥引起的一些突觸可塑性改變正?;ㄟ^調(diào)控這些結(jié)構(gòu)中對藥物強(qiáng)化作用有反應(yīng)的BDNF信號傳遞。
運(yùn)動對BDNF作用的潛在分子機(jī)制仍然未知。Wrann等[72]發(fā)現(xiàn),耐力訓(xùn)練能選擇性地誘導(dǎo)小鼠海馬區(qū)氧化物酶體增殖活化受體γ共激活因子-1α (peroxisome proliferator-activated receptor gamma coactivator 1-alpha,PGC-1α)和含Ⅲ型纖連蛋白域蛋白5(fibronectin typeⅢdomain containing protein 5,F(xiàn)NDC5)基因的表達(dá),過表達(dá)或者敲除PGC-1α分別會增加或降低FNDC5基因的表達(dá),這些發(fā)現(xiàn)證明PGC-1α能調(diào)控FNDC5基因的表達(dá)。而FNDC5在皮質(zhì)神經(jīng)元表達(dá)時會增加BDNF的表達(dá),RNAi介導(dǎo)的FNDC5基因敲除能減少BDNF的表達(dá)。FNDC5最先被運(yùn)動誘導(dǎo)的肌肉蛋白識別,分泌鳶尾素(irisin,F(xiàn)NDC5表達(dá)量大小通過檢測血液中的鳶尾素量得知),這是運(yùn)動對健康產(chǎn)生保護(hù)效應(yīng)的機(jī)制之一[73]。此外,運(yùn)動能選擇性地誘導(dǎo)海馬區(qū)REEA基因的表達(dá),PGC-1α過表達(dá)會增加雌激素相關(guān)受體α(estrogen-related receptor-α,ERR-α)基因(結(jié)合伴侶)表達(dá),破壞ERR-α/PGC-1α復(fù)合物會減少FNDC5的表達(dá)[72]。因此,運(yùn)動誘導(dǎo)海馬區(qū)BDNF基因表達(dá),可能通過選擇性地增加轉(zhuǎn)錄復(fù)合物ERR-α/PGC-1α,而刺激FNDC5基因表達(dá),進(jìn)而提高海馬區(qū)BDNF水平調(diào)控[74]。
總之,運(yùn)動能提高大腦BDNF水平,通過表觀遺傳調(diào)節(jié)包含BDNF基因的染色質(zhì)結(jié)構(gòu),降低藥物濫用易感性,減少復(fù)吸。
運(yùn)動通過影響神經(jīng)遞質(zhì)系統(tǒng)、突觸可塑性、信號分子、神經(jīng)再生、表觀遺傳和BDNF等對成癮者產(chǎn)生長時程保護(hù)作用。從分子機(jī)制上通過神經(jīng)適應(yīng)性調(diào)節(jié)降低藥物濫用易感性,改變?nèi)旧|(zhì)結(jié)構(gòu)從而減少覓藥行為,通過增強(qiáng)海馬區(qū)神經(jīng)再生和PFC膠質(zhì)細(xì)胞再生緩沖對抗適應(yīng)藥物濫用的不良模式,減少復(fù)吸。值得注意的是,運(yùn)動的條件不同會產(chǎn)生不同的神經(jīng)生物學(xué)效應(yīng)。有些甚至帶來與藥物依賴相似的神經(jīng)生物學(xué)改變。這與運(yùn)動的水平、類型、時間有關(guān),未來還需要更多的研究確定運(yùn)動能產(chǎn)生最大保護(hù)作用的條件,研究其分子機(jī)制,并設(shè)計出最優(yōu)方案來治療成癮者和保護(hù)濫用高危人群。運(yùn)動對相關(guān)腦區(qū)神經(jīng)遞質(zhì)、認(rèn)知功能及表觀遺傳學(xué)等方面研究相對較多,而運(yùn)動對藥物依賴的神經(jīng)生物學(xué)作用研究甚少。流行病學(xué)研究發(fā)現(xiàn),運(yùn)動訓(xùn)練與吸毒程度的負(fù)相關(guān)關(guān)系,運(yùn)動對生理和心理有有益作用,運(yùn)動戒毒勢必作為未來的一種潛在的、有效的、預(yù)防和治療藥物依賴的措施。闡明其有效性的神經(jīng)機(jī)制,亦成為未來研究的熱點。此外,運(yùn)動作為一種藥物依賴的輔助治療手段鮮見報道,其藥物相互作用機(jī)制也未能得知。根據(jù)現(xiàn)有的研究表明,運(yùn)動聯(lián)合藥物治療能起到節(jié)約開支、增加治療結(jié)果的作用。探索其輔助治療的條件及闡明其機(jī)制也是未來研究的一個熱點。
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Exercise intervention for drug dependence:evidence from neurobiological mechanism research
KE Yu-ting1,ZHOU Wen-hua1,2
(1.School of Medicine,Ningbo University,Ningbo315211,China;2.Ningbo Addiction Research and Treatment Center,Ningbo315000,China)
Epidemiological studies reveal that individuals who are engaged in regular aerobic exercise are less prone to drug abuse.Results from animal and human studies indicate that exercise may serve as a potential intervention for drug dependence,producing beneficial and lasting protective effects on different phases of the addiction process.The beneficial effects are connected with neural adaptation which is related to drug dependence.Exercise can regulate various neurotransmitter systems and intracellular signal transmission,increasing levels of brain-derived neurotrophic factors,promoting hippocampal neurogenesis and regulating epigenetic molecular mechanisms in resistance to and/or recovery from drug addiction.Therefore,exercise plays an important role in reducing drug carving and preventing relapse.Moreover,exercise generally produces different neurobiological mechanisms,depending on the level/type/timing of exercise exposure,the stage of addiction,the drug involved,and the subject population.This paper,from the perspective of neurobiological mechanisms,reviews exercise-based interventions alone or as an adjunct to other strategies for treating drug addiction.
exercise;substance-related disorders;neuroplasticity
The project supported by National Key Technology R&D Program in the 12th Five-Year Plan of China(2012BAI01B07);and National Natural Science Foundation of China(U1132602)
ZHOU Wen-hua,E-mail:whzhou@vip.163.com,Tel:(0574)87273530
R964
:A
:1000-3002(2015)04-0599-08
10.3867/j.issn.1000-3002.2015.04.011
2014-11-18 接受日期:2015-03-03)
(本文編輯:喬 虹)
“十二五”支撐項目(2012BAI01B07);國家自然科學(xué)基金(U1132602)
柯鈺婷,女,碩士研究生,從事藥物成癮機(jī)制及防治的研究,E-mail:killua5213@163.com;周文華,男,研究員,主要從事海洛因成癮防治及神經(jīng)生物學(xué)機(jī)制的研究。
周文華,E-mail:whzhou@vip.163.com,Tel:(0574)87273530