■肌内(IM)热针治疗,非疼痛的热疗,已发现通过丘脑腹内侧(VM)核发挥镇痛作用,仅通过降低下降抑制的触发阈值;这可以由脑内5-羟色胺-1A(5-HT1A)受体调节,而不是通过常规的镇痛途径。在这项研究中,在腰椎间盘突出症(LDH)的病理状态下,探讨了在43°C下IM加热针刺激的作用和潜在的血清素能机制。
■改良的经典LDH大鼠模型,通过自体髓核植入诱导,被利用。IM内部加热针应用于L4和L5棘突两侧的骨骼肌附着点。WAY-100635和8-OH-DAPT,5-HT1A受体拮抗剂和激动剂,通过丘脑内导管分别注射到双侧丘脑中背核(MD)和VM核中。通过有害的机械和热刺激引起的双侧爪退缩反应来评估伤害感受。
■在43°C的温度下,IM加热针刺激30或45分钟显着缓解了LDH大鼠模型的机械和热痛觉过敏(P<0.05)。通过将WAY-100635施用到丘脑VM核中,发现热痛觉过敏显着增强,以剂量依赖性方式阻断热针刺激的效应(P<0.05),而注射入丘脑MD核后未检测到影响(P>0.05)。丘脑MD核内注射8-OH-DAPT对机械痛觉过敏和热痛觉过敏均无调节作用(P>0.05)。
■在43°C下进行30分钟的IM加热针刺激可能会激活5-HT1A机制,通过丘脑VM核,减轻LDH大鼠模型的痛觉过敏。这种无害形式的热刺激被推测为选择性地激活由丘脑VM核介导的下降抑制,发挥镇痛作用,不参与丘脑MD核的下降促进。
UNASSIGNED: Intramuscular (IM) heating-needle therapy, a non-painful thermal therapy, has been found to exert an analgesic effect via the thalamic ventromedial (VM) nucleus, solely by reducing the triggering threshold for descending inhibition; this could be modulated by intracephalic 5-hydroxytryptamine-1A (5-HT1A) receptors, rather than via the regular analgesia pathway. In this study, the effect and the potential serotonergic mechanism of IM heating-needle stimulation at 43°C were explored in the case of the pathological state of lumbar disc herniation (LDH).
UNASSIGNED: A modified classic rat model of LDH, induced via autologous nucleus pulposus implantation, was utilized. IM inner heating-needles were applied at the attachment point of skeletal muscle on both sides of the L4 and L5 spinous processes. WAY-100635 and 8-OH-DAPT, 5-HT1A receptor antagonist and agonist, were separately injected into the bilateral thalamic mediodorsal (MD) and VM nucleus via an intrathalamic catheter. Nociception was assessed by bilateral paw withdrawal reflexes elicited by noxious mechanical and heat stimulation.
UNASSIGNED: IM heating-needle stimulation at a temperature of 43°C for 30 or 45 min significantly relieved both mechanical and heat hyperalgesia in the rat model of LDH (P < 0.05). Heat hyperalgesia was found to be significantly enhanced by administration of WAY-100635 into the thalamic VM nucleus, blocking the effect of heating-needle stimulation in a dose-dependent manner (P < 0.05), while no effects were detected after injection into the thalamic MD nucleus (P > 0.05). Injection of 8-OH-DAPT into the thalamic MD nucleus exerted no modulating effects on either mechanical or heat hyperalgesia (P > 0.05).
UNASSIGNED: IM heating-needle stimulation at 43°C for 30 min may activate 5-HT1A mechanisms, via the thalamic VM nucleus, to attenuate hyperalgesia in a rat model of LDH. This innocuous form of thermal stimulation is speculated to selectively activate the descending inhibition mediated by the thalamic VM nucleus, exerting an analgesic effect, without the involvement of descending facilitation of the thalamic MD nucleus.