Study on the mechanisms of oro-facial and temporomandibular joint neuropathic pain control in the central nervous system

口部伤害性信息主要在眶上部的吻侧TSN、主核（Vp）、口亚核（SpVo）和极间亚核（SpVi）进行加工，其次在尾侧亚核（SpVc）进行加工。相反，面部伤害性信号主要在SpVc中处理。向丘脑投射的神经元主要分布在Vp，SpVi次之，SpVo腹外侧和SpVc次之。口面感觉输入以许多不同的方式调制;即通过TSN中的中间神经元，通过TSN和延髓头端腹内侧之间的相互连接，以及通过大脑皮质。P物质、γ-氨基丁酸（GABA）、5-羟色胺（5-HT）和一氧化氮（NO）等多种神经活性物质参与了这些回路的调节功能。我们发现，NK-1轴承神经元在SpVc中的感觉方式和强度依赖性伤害性加工通过GABAA受体的关键作用。在胚胎第15天，在SpVo中的离散神经元群体中观察到发育中大鼠脑中NO合酶（NOS）的最早表达。NOS在SpVc中的表达晚于出生后10天。接受口内信号的神经元通过SpVo与感觉运动反射功能密切相关。深入了解三叉神经感觉系统与脊髓感觉系统的区别，将有助于寻找潜在的治疗靶点，开发高效、副作用小的口面特异性疼痛镇痛药物。

The oral nociceptive signal is primarily processed in the rostral TSN above the obex, the nucleus principalis (Vp), and the subnuclei oralis (SpVo) and interpolaris (SpVi), while secondarily processed in the subnucleus caudalis (SpVc). In contrast, the facial nociceptive signal is primarily processed in the SpVc. The neurons projecting to the thalamus are localized mostly in the Vp, moderately in the SpVi, modestly in the ventrolateral SpVo and.the SpVc. Orofacial sensory inputs are modulated in many different ways; i.e. by interneurons in the TSN proper, through reciprocal connection between TSN and rostral ventromedial medulla, and by cerebral cortex. A wide variety of neuroactive substances, including substance P,γ^- aminobutyric acid (GABA), serotonin and nitric oxide (NO) could be involved in these circuits' modulatory functions. We found NK-1-bearing neurons in the SpVc have pivotal role in sensory modality-and intensity-dependent nociceptive processing through GABAA receptors. The earliest expression of NO synthase (NOS) in the developing rat brain is observed in a discrete neuronal population in the SpVo at embryonic day 15. NOS expression in the SpVc is late at postnatal day 10. The neurons receiving intraoral signals are intimately related with the sensorimotor reflexive function through the SpVo. Better understanding of the trigeminal sensory system, which is different from the spinal system, will help to find potential therapeutic targets and render developing new analgesics for orofacial-specific pain with high efficacy and less side effects.