Caudal Nucleus Tractus Solitarius (NTS)在針灸改變睡眠所扮演的角色

The Role of Caudal Nucleus Tractus Solitarius (NTS) In Electroacupuncture-induced Sleep Activities

鄭穹翔(Chiung-Hsiang Cheng)

指導教授 ： 張芳嘉

國立臺灣大學/獸醫專業學院/獸醫學研究所/博士(2012年)

https://doi.org/10.6342/NTU.2012.00583

摘要

電針刺激可以有許多治療功用，例如止痛、消炎、治療睡眠障礙。電針刺激改善睡眠的機制目前還不明瞭。在中醫理論裡：安眠穴，是一個可以改善失眠的穴道。之前發現10Hz電針刺激安眠穴可以使孤獨徑核 (nucleus tractus solitaries, NTS) 的乙醯膽鹼性神經活化，造成大鼠在暗期的非快速動眼睡眠(non-rapid eye movement sleep; NREM sleep) 上升。我們假設除了乙醯膽鹼類神經外，內生性嗎啡也可能是影響電針在睡眠的作用。本研究結果顯示，10Hz電刺激安眠穴增加了暗期的非快速動眼睡眠但是不影響快速動眼睡眠 (rapid eye movement sleep; REM sleep)，且這些增加的NREM可以被注射到NTS的naloxone (opioid receptor antagonist) 和naloxonazine (μ-opioid receptor antagonist拮抗) 抑制。而注射natrindole (σ-opioid receptor) 和 nor-binaltrophimine (κ-opioid receptor) 則沒有作用。除此之外β-endorphin的表現量在10Hz電針刺激後於腦幹和海馬迴都有上升且會被注射到NTS的muscarinic antagonist: scopolamine拮抗。我們的結果顯示10Hz電刺激安眠穴增加的非快速動眼可能是藉由乙醯膽鹼活化後使opiodergic 神經分泌β-endorphin增高，作用在μ-opioid receptor。
解剖上，從 NTS 來的神經投射到 parabrachial nuclei (PBN)，再投射到視丘的腹內側神經核 (ventromedial nucleus of the thalamus; VM)；或直接由 NTS 投射到視丘的腹內側神經核。清醒時腦中皮質的神經突觸活性較強，但在睡眠時的神經活動基本上會減少這些突觸的活性。從 NTS 到 PBN 以及 VM 的嗎啡類神經藉由嗎啡類受體過極化了PBN 以及 VM 中的神經。因此我們假設 10 Hz 電針刺激增加 NTS 的突觸活性，造成PBN 以及 VM 的過極化，導致增加睡眠的現象。我們接著研究10 Hz 電針刺激安眠穴後，NTS 和 VM 的突觸密度和長度的改變。我們發現 10 Hz 電針刺激安眠穴後 NTS 和 VM 的突觸密度都有增加，但是突觸總長度只有在 NTS 部位有顯著改變。這實驗結果可能代表了電針刺激會增加興奮性突觸的長度以及密度來增強 NTS 的突觸強度，並且在 VM 增加抑制性突觸的密度來減低 VM 的突觸強度，並藉此達到電針安眠穴增加睡眠的作用。
有報告指出不同頻率的電針刺激可以增加不同種的內源性嗎啡，且作用在不同的類嗎啡受體上。因此我們接著使用100 Hz的電針刺激安眠穴發現也增加非快速動眼睡眠，但不會影響快速動眼睡眠。100Hz電刺激增加的非快速動眼睡眠會因為注射naloxone (opioid receptor antagonist)和nor-binaltrophimine (κ-opioid receptor)到NTS而抑制，但注射naloxonazine (μ-opioid receptor antagonist拮抗) 和natrindole (σ-opioid receptor) 不會影響非快速動眼睡眠。我們的結果顯示高頻率100 Hz的電針刺激可能會藉由NTS的κ-opioid receptor增加非快速動眼睡眠。這些結果顯示低頻率 (10Hz) 以及高頻率 (100Hz) 電刺激安眠穴均會增加非快速動眼睡眠，其機轉和電針止痛在脊髓的機制類似，低頻刺激增加β-endorphin在NTS釋放，作用在μ-receptor；而高頻刺激則是藉由κ-receptor。

關鍵字

電針刺激(electroacupuncture, EA) ； 孤獨徑核(nucleus tractus solitaries ； NTS) ； β-endorphin ； μ-opioid receptor ； κ-opioid receptor ； 睡眠 ； 突觸形態 ； 視丘的腹內側神經核 (ventromedial nucleus of the thalamus ； VM)

並列摘要

Electroacupuncture (EA) possesses various therapeutic effects, including alleviation of pain, reduction of inflammation and improvement of sleep disturbance. The mechanisms of EA on sleep improvement, however, remain to be determined. It has been stated in ancient Chinese literature that the Anmian (EX17) acupoint is one of the trigger points that alleviates insomnia. We previously demonstrated that EA stimulation of Anmian acupoints in rats during the dark period enhanced non-rapid eye movement (NREM) sleep, which involves the induction of cholinergic activity in the nucleus tractus solitarius (NTS). In addition to cholinergic activation of the NTS, activation of the endogenous opioidergic system may also be a mechanism by which acupuncture affects sleep. Therefore, this study was designed to investigate the involvement of the NTS opioidergic system in EA-induced alterations in sleep. Our present results indicate that EA of Anmian acupoints increased NREM sleep, but not rapid eye movement (REM) sleep, during the dark period in rats. This enhancement in NREM sleep was dose-dependently blocked by microinjection of opioid receptor antagonist, naloxone, and the μ-opioid receptor antagonist, naloxonazine, into the NTS; administrations of δ-receptor antagonist, natrindole, and the κ-receptor antagonist, nor-binaltrophimine, however, did not affect EA-induced alterations in sleep. Furthermore, β-endorphin was significantly increased in both the brainstem and hippocampus after the EA stimuli, an effect blocked by administration of the muscarinic antagonist scopolamine into the NTS. Our findings suggest that mechanisms of EA-induced NREM sleep enhancement may be mediated, in part, by cholinergic activation, stimulation of the opiodergic neurons to increase the concentrations of β-endorphin and the involvement of the μ-opioid receptors.
One ascending projection is from NTS to the ventromedial nucleus (VM) of the thalamus (the NTS-VM pathway). Wakefulness is accompanied by synaptic potentiation in the cortical circuits, whereas slow wave activity (SWA) during slow wave sleep (SWS) promotes a generalized depression or downscaling of synaptic strength. The VM receives opioidergic inputs from NTS and the activation of opioid receptors hyperpolarize neurons of VM. Accordingly, 10 Hz EA may increase synaptic activity of NTS and subsequently hyperpolarize and downscale the synaptic strength in the VM of thalamus by inhibitory afferents, which lead to the enhancement of SWS. Enhancement of excitatory synapses in NTS and inhibitory synapses in VM may respectively contribute to the up-regulation of synaptic strength in NTS and downscaling of synaptic strength in the VM after 10 Hz EA. Our results demonstrated that the synaptic density was increased in both NTS and VM after rats received 10 Hz EA stimuli, while the enhanced synaptic length was only observed in the NTS, suggesting that 10 Hz EA altered excitatory synaptic strength of NTS and inhibitory synaptic strength of VM by changing the synaptic morphology.
Studies have shown that different kinds of endogenous opiate peptides and receptors may mediate the consequences of EA with different frequencies. Herein we further elucidated that high frequency (100 Hz) EA of Anmian enhanced NREM sleep during the dark period, but exhibited no direct effect on REM sleep. High frequency EA-induced NREM sleep enhancement was dose-dependently blocked by microinjection of naloxone or κ-receptor antagonist (nor-binaltrophimine) into the caudal NTS, but was affected neither by μ-(naloxonazine) nor δ-receptor antagonists (natrindole), suggesting the role of NTS κ-receptors in the enhancement of high frequency EA-induced NREM sleep. Current and previous results have combined to depict the opioid mechanisms of EA-induced sleep.

並列關鍵字

electroacupuncture (EA) ； nucleus tractus solitaries (NTS) ； β-endorphin ； μ-opioid receptor ； κ-opioid receptor ； sleep ； synaptic morphology ； ventromedial nucleus of the thalamus (VM)

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