【摘要】：目的:在成年動(dòng)物,γ-氨基丁酸(GABA)作為重要的抑制性神經(jīng)遞質(zhì),可通過(guò)激動(dòng)A-型GABA受體(GABA_A受體),影響神經(jīng)元的興奮性。突觸中的GABA_A受體介導(dǎo)瞬時(shí)抑制(phasic inhibition),而突觸外的GABA_A受體則介導(dǎo)持久性抑制(tonic inhibition)。研究顯示:突觸外的GABA_A受體主要包含α_5亞基(即:α_5-GABA_A受體)和δ亞基(即:δ-GABA_A受體)。大量的實(shí)驗(yàn)已經(jīng)探討了GABA能瞬時(shí)抑制對(duì)谷氨酸能突觸傳遞效率的影響。然而,持久性抑制對(duì)脊髓背角突觸傳遞和突觸可塑性的影響還不明確。本文探討了GABA能持久性抑制對(duì)C纖維誘發(fā)的場(chǎng)電位(C fiber-evoked field potentials)長(zhǎng)時(shí)程增強(qiáng)(Long-Term Potential,LTP)的調(diào)控作用。方法:本文通過(guò)電生理方法,在大鼠脊髓背角記錄C纖維誘發(fā)的場(chǎng)電位;低頻電刺激(Low Frequency Stimulation,LFS)誘發(fā)LTP;脊髓局部給予α_5-GABA_A受體抑制劑L-655,708(20 nM)或δ-GABA_A受體激動(dòng)劑THIP(2μM),觀察LTP的誘導(dǎo)及幅值的變化,研究突觸外膜GABA_A受體對(duì)痛覺(jué)突觸傳遞的調(diào)控作用及其機(jī)制。結(jié)果:(1)給予大鼠坐骨神經(jīng)2 min的低頻電刺激(60 V,0.5-ms duration,2 Hz)可穩(wěn)定誘發(fā)LTP,且LTP至少可以維持3 h。滴加生理鹽水不影響正常場(chǎng)電位及LTP的幅值。(2)脊髓局部滴加α_5-GABA_A受體的特異性抑制劑L-655,708(20 nM)可明顯增大C纖維的基礎(chǔ)電位幅值,提示:α_5-GABA_A受體的去抑制可增強(qiáng)C纖維支配的突觸傳遞。(3)低頻電刺激前用L-655,708(20 nM)預(yù)處理脊髓1 h,能夠促進(jìn)C纖維誘發(fā)場(chǎng)電位LTP的形成、顯著提高LTP的幅值,提示:抑制α_5-GABA_A受體可易化LTP的誘導(dǎo)。(4)低頻電刺激前,用L-655,708(20 nM)先作用30 min,再給脊髓局部滴加“包含GluN2B亞基的NMDA型谷氨酸受體(GluN2B受體)”的特異性抑制劑ifenprodil(10μg),能夠阻斷L-655,708對(duì)LTP的增強(qiáng)作用,提示:α_5-GABA_A受體可能通過(guò)GluN2B受體調(diào)控LTP的誘導(dǎo)。(5)L-655,708(20 nM)作用30 min后,脊髓背角滴加“包含GluN2A亞基的NMDA受體(GluN2A受體)”的選擇性抑制劑TCN-201(10μM),不影響低頻電刺激誘導(dǎo)LTP。(6)低頻電刺激30 min和3 h后,分別用L-655,708(20 nM)處理脊髓背角,能使早期和晚期LTP的幅值進(jìn)一步增強(qiáng);(7)脊髓滴加δ-GABA_A受體的特異性激動(dòng)劑THIP(2μM),對(duì)C纖維基礎(chǔ)電位幅值無(wú)明顯影響,但能夠降低低頻電刺激引發(fā)的LTP幅值。(8)低頻電刺激3 h后再用THIP(2μM)處理脊髓,可顯著降低晚期LTP幅值。結(jié)論:介導(dǎo)持久性抑制的突觸外膜α_5-GABA_A受體和δ-GABA_A受體參與脊髓背角LTP的調(diào)節(jié)。
[Abstract]:Aim: in adult animals, 緯-aminobutyric acid (GABA), as an important inhibitory neurotransmitter, can affect the excitability of neurons by activating the A-type GABA receptor (GABA_A receptor). GABA_A receptor in synapse mediates transient inhibition of (phasic inhibition), while extrasynaptic GABA_A receptor mediates persistent inhibition of (tonic inhibition). The results show that the extrasynaptic GABA_A receptors mainly contain 偽 _ 5 subunit (偽 _ 5-GABA_A receptor) and 未 subunit (未-GABA_A receptor). A large number of experiments have investigated the effect of transient inhibition of GABA energy on synaptic transmission efficiency of glutamic acid. However, the effects of persistent inhibition on synaptic transmission and synaptic plasticity in spinal dorsal horn are unclear. The regulatory effect of persistent inhibition of GABA on C-fiber-evoked field potentials) evoked field potentials (C-fiber-evoked field potentials) long-term potentiation (Long-Term Potential,LTP) was investigated in this paper. Methods: the field potentials evoked by C fibers were recorded in the dorsal horn of the spinal cord of rats by electrophysiological method, and the LTP; was induced by low frequency electrical stimulation (Low Frequency Stimulation,LFS). Local administration of 偽 _ 5-GABA_A receptor inhibitor L _ 5-GABA_A receptor inhibitor (20 nM) or 未-GABA_A receptor agonist THIP (2 渭 M) was given to the spinal cord to observe the induction and amplitude change of LTP. To study the regulation and mechanism of GABA_A receptor on pain synaptic transmission. Results: (1) low-frequency electrical stimulation (60 V, 0.5 Ms duration,2 Hz) of sciatic nerve (60 V, 0.5 Ms duration,2 Hz) could induce LTP, stably and LTP could be maintained for at least 3 h. The normal field potential and the amplitude of LTP were not affected by the drip of saline. (2) the basal potential amplitude of C fiber was significantly increased by local drip of 偽 _ 5-GABA_A receptor inhibitor L, 655708 (20 nM) in spinal cord. These results suggest that de-inhibition of 偽 _ 5-GABA_A receptor can enhance synaptic transmission innervated by C fibers. (3) pretreatment of spinal cord with low frequency electrical stimulation for 1 hour can promote the formation of evoked field potential (LTP) of C fibers. It was suggested that the inhibition of 偽 _ 5-GABA_A receptor could facilitate the induction of LTP. (4) before low-frequency electrical stimulation, the inhibition of 偽 _ 5-GABA_A receptor could induce the induction of LTP. (4) before low-frequency electrical stimulation, the inhibitory effect of L _ 5-GABA_A receptor on the induction of LTP was 30 min, first. Ifenprodil (10 渭 g), a specific inhibitor of "NMDA glutamic acid receptor (GluN2B receptor) containing GluN2B subunit" was added to the spinal cord to block the enhancement of LTP induced by LA 655708. These results suggest that 偽 _ 5-GABA_A receptor may regulate the induction of LTP through GluN2B receptor. (5) after 30 min treatment with Lac 655708 (20 nM), it is suggested that 偽 _ TNF receptor may regulate the induction of LTP. The addition of selective inhibitor TCN-201 (10 渭 M) to "NMDA receptor (GluN2A receptor) containing GluN2A subunit" in spinal dorsal horn did not affect the low frequency electrical stimulation of LTP. (6) induced by low frequency electrical stimulation for 30 min and 3 h. The amplitude of LTP in the early and late stage of spinal cord could be further enhanced by the treatment of spinal dorsal horn with L, 655708 (20 nM), respectively. (7) THIP (2 渭 M), a specific agonist of 未-GABA_A receptor, did not affect the amplitude of basic potential of C fiber. (8) after 3 hours of low frequency electrical stimulation, the spinal cord was treated with THIP (2 渭 M), and the amplitude of late LTP was decreased significantly. (3) the amplitude of LTP induced by low frequency electrical stimulation was decreased significantly after 3 hours of low frequency electrical stimulation. Conclusion: 偽 _ 5-GABA_A receptor and 未-GABA_A receptor, which mediate persistent inhibition, are involved in the regulation of LTP in spinal dorsal horn.
【學(xué)位授予單位】：蘭州大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：R402

【相似文獻(xiàn)】

相關(guān)期刊論文 前10條

1 龔良維,丁玉強(qiáng),呂巖,鄭恒興,秦秉志,李繼碩;代謝型谷氨酸受體五種亞型在貓脊髓內(nèi)的分布—免疫組織化學(xué)方法研究[J];中國(guó)組織化學(xué)與細(xì)胞化學(xué)雜志;1998年01期

2 魏祥品;慢性脊髓刺激治療疼痛[J];立體定向和功能性神經(jīng)外科雜志;2002年03期

3 劉燕,陳娟,韓建德,徐迎新,羅力,徐承燾,張艷萍;辣椒素引起脊髓 P 物質(zhì)釋放及其對(duì)血壓的影響[J];生理學(xué)報(bào);1990年05期

4 龍雙漣,李朗,孫俊,傅希s，

本文編號(hào)：2442050