Akpinar Sevket, Aydin Hamdullah, Kutukcu Yasar
Department of Neurology, Gülhane Military Medical Academy, Medical Faculty-Etlik, Ankara, Turkey.
Med Hypotheses. 2007;69(2):273-81. doi: 10.1016/j.mehy.2006.12.027. Epub 2007 Feb 21.
RLS cases may carry a genetic vulnerability called EEG alpha activity gate dyscontrols which appear during changes in vigilance and generally during sleep. It is triggered by forced EEG shifts either from alpha activity to delta or high alpha. Expressions of alpha activity gate dyscontrols may have a gate effect that trigger a second vulnerability-dopamine receptor specific individual sensitivity (DRSIS) and this leads to a deficiency in dopamine transmissions at diencephalospinal dopamine system (DSDS). Due to altered gene expressions in states of dopamine receptor function, DRSIS EEGs and RLS symptoms may be interpreted as follows: A. Disinhibition state is alpha activity gate dyscontrols induced inhibition of DSDS inhibitory dopamine modulations. Dopaminergic disinhibitions inhibit inhibitory interneurons of sensory and motor nuclei neurons that are involved in RLS. These sleep sensitive inhibitory interneurons possibly have GABA-ergic functions in sleep. (I) DSDS thalamic neurons' disinhibitory effects in thalamus on GABA-ergic interneurons of: (a) Intralaminar nuclei non-discriminative sensation neurons at thalamocortical premotor network leading to symptom of "a sense of urgency to move" generally referenced to legs.(b) Reticular thalamic nucleus (RTN) neurons. At polysomnography,during NREM sleep, disinhibited RTN neurons show alpha activity gate dyscontrol 1. These are recurrent subtypes of CAP in alpha band (7-12 Hz) pointing a difficulty in shifting to subtypes of CAP in low delta bands (0.25-2.5 Hz) and sleep fragmentations.(II) Supraspinal disinhibitory projections from DSDS thalamic neurons on GABA-ergic interneurons of: (a) Sensory neurons at posterior horns of spinal cord leading to dysesthesias, generally referenced to legs.(b) Medullary-reticulospinal neurons and by way of independent spinal rhythm generators on motoneurons leading to periodic limb movements in sleep.B. Activation state is an increase in symptoms. Sensory intralaminar and motor pontin nuclei neurons are in fact excitatory but are disinhibited in RLS. Due to altered gene expression, these neurons begin to perceive 'disinhibition' as reduced inhibition. Their glutamate receptors may activate deficient dopamine transmissions on RTN leading to alpha activity gate dyscontrol 2. This implies a failure in preventing shifts to frequent subtypes of CAP in high alpha and low beta bands (12-13 Hz) resulting in an increase of sensorimotor symptoms and appearance of motor restlessness, behavioral arousals and insomnia. C. Inhibition state is spontaneous relief from sensorimotor symptoms. Short or long-term synaptic plasticities of dopamine receptors towards activations initiate negative feedbacks from inhibitory interneurons. They are supported by inhibitory dopamine modulations- alertness and some awareness generally with regular high alpha EEGs, supraspinal inhibitions and a reverse movement pattern of PLMS during standing up and continuing to walk.
不宁腿综合征(RLS)病例可能携带一种名为脑电图α活动门控失调的遗传易感性,这种情况出现在警觉性变化期间,通常在睡眠期间出现。它由脑电图从α活动强制转变为δ波或高α波所触发。α活动门控失调的表现可能具有一种门控效应,触发第二种易感性——多巴胺受体特异性个体敏感性(DRSIS),这导致间脑脊髓多巴胺系统(DSDS)中多巴胺传递不足。由于多巴胺受体功能状态下基因表达的改变,DRSIS脑电图和RLS症状可如下解释:A.去抑制状态是α活动门控失调诱导的DSDS抑制性多巴胺调节的抑制。多巴胺能去抑制抑制参与RLS的感觉和运动核神经元的抑制性中间神经元。这些对睡眠敏感的抑制性中间神经元在睡眠中可能具有GABA能功能。(I)DSDS丘脑神经元在丘脑中对以下GABA能中间神经元的去抑制作用:(a)丘脑皮质运动前网络中的板内核非辨别性感觉神经元,导致通常指腿部的“运动紧迫感”症状。(b)丘脑网状核(RTN)神经元。在多导睡眠图中,在非快速眼动睡眠期间,去抑制的RTN神经元表现出α活动门控失调1。这些是α波段(7 - 12赫兹)中CAP的复发性亚型,表明难以转变为低δ波段(0.25 - 2.5赫兹)中CAP的亚型以及睡眠碎片化。(II)DSDS丘脑神经元对以下GABA能中间神经元的脊髓上抑制性投射:(a)脊髓后角的感觉神经元,导致感觉异常,通常指腿部。(b)延髓网状脊髓神经元,并通过独立的脊髓节律发生器作用于运动神经元,导致睡眠中的周期性肢体运动。B.激活状态是症状的增加。感觉板内核和运动脑桥核神经元实际上是兴奋性的,但在RLS中被去抑制。由于基因表达改变,这些神经元开始将“去抑制”视为抑制减少。它们的谷氨酸受体可能激活RTN上不足的多巴胺传递,导致α活动门控失调2。这意味着无法防止转变为高α和低β波段(12 - 13赫兹)中频繁的CAP亚型,从而导致感觉运动症状增加以及运动不安、行为觉醒和失眠的出现。C.抑制状态是感觉运动症状的自发缓解。多巴胺受体对激活的短期或长期突触可塑性启动抑制性中间神经元的负反馈。它们由抑制性多巴胺调节支持——警觉性和一些意识,通常伴有规则的高α脑电图、脊髓上抑制以及站立和继续行走时PLMS的反向运动模式。