【摘要】： 晝夜節(jié)律貫穿于所有生物體生命活動的始終。下丘腦視交叉上核(SCN)作為哺乳動物晝夜節(jié)律的主起搏器(生物鐘)已經(jīng)得到許多實驗的證明,并一直成為許多學者關注的熱點。而韁核是目前少有的已被證實自身可呈現(xiàn)出與SCN相似節(jié)律性振蕩的腦內(nèi)核團,且其與SCN之間還存在著密切的形態(tài)學與功能學上的聯(lián)系。另外,韁核與晝夜節(jié)律系統(tǒng)中另一重要結(jié)構(gòu)——松果體之間也存在著獨有的解剖學關系及密切的功能聯(lián)系。因此,韁核很可能在晝夜節(jié)律系統(tǒng)的調(diào)節(jié)中發(fā)揮重要的作用。 本研究首先通過實驗觀察在持續(xù)黑暗(DD)及光暗周期(LD)條件下?lián)p毀韁核對大鼠自發(fā)活動晝夜節(jié)律的影響,隨后運用高效液相色譜(HPLC)熒光法檢測不同條件下韁核損毀大鼠紋狀體內(nèi)的多巴胺(DA)及5-羥色胺(5-HT)含量變化,試圖揭示韁核損毀對大鼠跑輪活動影響的作用機制。同時,本研究還應用HPLC檢測了韁核損毀大鼠松果體內(nèi)褪黑素(Mel)的含量變化、應用透射電鏡技術(shù)觀察了韁核損毀對松果體細胞超微結(jié)構(gòu)的影響及運用電生理學技術(shù)研究離體腦片韁核神經(jīng)元對不同劑量Mel的反應,以考察韁核在松果體和Mel所參與晝夜節(jié)律調(diào)節(jié)過程中的作用。 結(jié)果顯示,韁核損毀大鼠在DD條件下仍表現(xiàn)為近似24h的自由運行周期不變,但自發(fā)活動在自由運轉(zhuǎn)周期內(nèi)的分布卻發(fā)生了顯著性變化。在LD條件下,韁核損毀可明顯加快大鼠對光照延后8 h再導引作用的反應速度,但不改變其對光照前移8 h再導引作用的反應。在DD條件下,韁核損毀大鼠紋狀體內(nèi)DA含量變化與自發(fā)跑輪活動在自由運轉(zhuǎn)周期內(nèi)分布的變化呈現(xiàn)反相關系:即在主觀夜晚,DA含量增加,跑輪活動所占的比例降低;在主觀白天,DA含量減少,而跑輪活動所占的比例明顯增高。在LD條件下,韁核損毀3周時紋狀體內(nèi)的DA含量在光時相及暗時相都表現(xiàn)為增加。而紋狀體內(nèi)的5-HT,無論是LD還是DD條件下,損毀3周時都只表現(xiàn)為暗時相/主觀夜晚時含量的增加。但LD條件下韁核損毀8周時紋狀體內(nèi)DA及5-HT的含量都表現(xiàn)為ZT4點的明顯降低。結(jié)果還顯示,韁核損毀后DD條件下松果體內(nèi)Mel含量無明顯變化。而在LD條件下松果體內(nèi)的Mel含量及松果體的重量在暗時相均明顯降低;同時,損毀大鼠的松果體細胞超微結(jié)構(gòu)也發(fā)生了顯著性的變化。此外,約有70%的韁核神經(jīng)元在離體給予Mel后可發(fā)生明顯性的放電變化,且不同濃度的Mel所引起的放電變化反應類型有明顯的不同。但是,韁核的不同亞核對10-7 mol/L Mel的反應無明顯的區(qū)域性差異。結(jié)果表明:韁核參與SCN產(chǎn)生的內(nèi)源性節(jié)律的調(diào)節(jié)過程,其機制可能有腦內(nèi)DA及5-HT系統(tǒng)的參與;同時韁核也可通過與松果體之間的相互作用關系進而實現(xiàn)其對晝夜節(jié)律的調(diào)節(jié),一方面韁核可通過對松果體的調(diào)控影響其內(nèi)Mel的合成和分泌,另一方面,它也是Mel在腦內(nèi)作用的重要靶點。
[Abstract]:The circadian rhythm runs through the life of all living organisms. As the main pacemaker (circadian clock) of mammalian circadian rhythm, the supraoptic nucleus of hypothalamus (SCN) has been proved by many experiments and has been a hot topic for many researchers. Habenular nucleus is one of the few nuclei which has been proved to exhibit rhythmic oscillations similar to that of SCN, and there is a close relationship between habenular nucleus and SCN in morphology and function. In addition, there is a unique anatomical relationship and close functional relationship between the habenular nucleus and the pineal gland, another important structure in the circadian rhythm system. Therefore, habenular nucleus may play an important role in the regulation of circadian rhythm system. In this study, the effects of continuous dark (DD) and light-dark period (LD) on the circadian rhythm of spontaneous activity of habenular nucleus in rats were studied. Then the changes of dopamine (DA) and 5-hydroxytryptamine (5-HT) in the striatum of rats with habenular nucleus lesion under different conditions were detected by high performance liquid chromatography (HPLC) fluorescence method in order to elucidate the mechanism of the effect of habenular nucleus damage on rat wheel running activity. At the same time, HPLC was used to detect the changes of melatonin (Mel) in the pineal gland of rats with habenular nucleus lesion. The effects of habenular nucleus lesion on ultrastructure of pineal cells were observed by transmission electron microscopy (TEM) and electrophysiological techniques were used to study the response of habenula neurons to different doses of Mel in vitro. To investigate the role of habenular nucleus in the regulation of circadian rhythm in the pineal gland and Mel. The results showed that the free cycle of habenular nucleus lesion remained unchanged in approximately 24 hours under DD, but the distribution of spontaneous activity in the free cycle changed significantly. Under the condition of LD, the damage of habenular nucleus could significantly accelerate the response of rats to light delayed 8 h reguidance, but it did not change its response to light forward 8 h re guidance. Under the condition of DD, the change of DA content in striatum of rats with habenular nucleus lesion was inversely related to the distribution of spontaneous wheel running activity in the free running cycle: in subjective night, the content of DA increased and the proportion of wheel running decreased. During the subjective day, the content of DA decreased and the proportion of wheel running increased significantly. Under the condition of LD, the content of DA in striatum was increased in both light phase and dark phase after 3 weeks of habenular nucleus lesion. However, 5-HT in striatum, whether under LD or DD, showed only the increase of dark phase / subjective night time at 3 weeks after lesion. However, the contents of DA and 5-HT in striatum were significantly decreased at 8 weeks after habenular nucleus lesion under LD condition. The results also showed that there was no significant change of Mel content in pineal body after habenular nucleus lesion under DD. The content of Mel in pineal gland and the weight of pineal gland decreased significantly in dark phase under LD condition, and the ultrastructure of pineal cells in damaged rats also changed significantly at the same time. In addition, about 70% of habenula neurons had obvious changes in discharge after in vitro administration of Mel, and the types of response to different concentrations of Mel were significantly different. However, there were no significant regional differences in response to 10-7 mol/L Mel in different subnuclei of habenular nucleus. The results showed that the habenular nucleus was involved in the regulation of endogenous rhythm produced by SCN, and the mechanism of habenular nucleus might be involved in the DA and 5-HT system in the brain, and the habenular nucleus could also regulate the circadian rhythm through the interaction with pineal gland. On the one hand, the habenular nucleus can affect the synthesis and secretion of Mel through the regulation of pineal body. On the other hand, it is also an important target of Mel in brain.
【學位授予單位】：吉林大學
【學位級別】：博士
【學位授予年份】：2010
【分類號】：R338

【引證文獻】

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1 褚峰;溫度對基于光授時信號途徑的家蠶BmN細胞生物鐘基因表達的影響[D];蘇州大學;2014年

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