The effect of analgesics on central nervous system following experimental tooth movement

正畸牙齿移动会引起疼痛和不适。当对牙齿施加正畸力时，牙周组织发生炎症并释放物质，这可能与痛觉机制有关。即时早期基因c-fos编码核蛋白Fos。突触激活后脑内Fos的诱导是神经元特有的，据报道，c-fos的激活被用作脑内神经突触通路追踪的代谢制造器。采用免疫组化方法研究实验性牙齿运动对大鼠脑c-fos表达的影响。在大鼠上磨牙间单侧置入正畸弹性模组。实验牙齿运动开始24小时后，三叉神经尾侧亚核和外侧臂旁核出现fos样免疫反应神经元，参与伤害性信息的传递。实验性牙齿运动后，实验大鼠前脑杏仁核中央核（ACE）、下丘脑室旁核（PVH）和丘脑室旁核（PV）均出现fos样免疫反应神经元。顺便说一下，n -甲基- d -天冬氨酸（NMDA）受体与疼痛的多个方面有关。我们检测了NMDA受体拮抗剂MK-801对实验性牙齿运动的影响。MK-801预处理大鼠前脑ACE、PVH和PV中fos样免疫反应神经元数量有减少的趋势。

Orthodontic tooth movement induces pain and discomfort. When an orthodontic force is applied to teeth, an inflammatory event occurs with the periodontium and substances are released, which could be related to the mechanism of pain sensation. Immediate early gene, c-fos, encodes the nuclear protein Fos. The induction of Fos in the brain following synaptic activation is specific for neurons, and c-fos activation has been reported to be utilized as a metabolic maker for neurosynaptic pathway tracing in the brain. We investigated the effect of experimental tooth movement on the c-fos expression in the rat brain by using Fos immunohistochemistry. An orthodontic elastic module was unilaterally inserted between upper molars of rats. Twenty-four hours after the commencement of the experimental tooth movement, Fos-like immunoreactive neurons appeared in the trigeminal subnucleus caudalis and in the lateral parabrachial nucleus, which is known to be involved in transmission of the nociceptive information. Following experimental tooth movement, the Fos-like immunoreactive neurons appeared in the central nucleus of the amygdala (ACE), paraventricular nucleus of the hypothalamus (PVH) and paraventricular nucleus of the thalamus (PV) of the experimental rat forebrain. By the way, the N-methyl-D-asparate (NMDA) receptor is implicated in multiple aspects of pain. We examined the influence of the NMDA receptor antagonist, MK-801 following experimental tooth movement. Pretreatment with MK-801 produced a tendency towards a reduction of the number of the Fos-like immunoreactive neurons appeared in ACE, PVH and PV of the rat forebrain.