Sex-related differences in human pain and rat afferent discharge evoked by injection of glutamate into the masseter muscle
Sex-related differences in human pain and rat afferent discharge evoked by injection of glutamate into the masseter muscle
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DOI：
10.1152/jn.2001.86.2.782
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发表时间：
2001-08-01
影响因子：
2.5
通讯作者：
Svensson, P
中科院分区：
文献类型：
--
作者：
Cairns, BE;Hu, JW;Svensson, P
动物研究表明，组织损伤相关的谷氨酸水平的增加可能参与颅面深部组织的外周伤害性机制。实际上，将谷氨酸盐（0.1-1 M，10穆尔）注射到颞下颌区域通过激活外周兴奋性氨基酸受体引起反射性颌肌反应。最近发现，这种谷氨酸诱发的反射肌肉活动在雌性大鼠中明显大于雄性大鼠。然而，目前尚不清楚是否外周施用谷氨酸，在相同的浓度，引起大鼠下颌肌肉活动，引起人类疼痛或激活深颅面伤害性传入。因此，我们研究了是否注射谷氨酸到咬肌引起疼痛的男性和女性志愿者，因为咬肌传入录音是不可行的，在人类中，谷氨酸是否兴奋假定的伤害性传入供应咬肌的男性和女性大鼠。将谷氨酸盐（0.5 M或1.0 M，0.2 ml）注射到男性和女性的咬肌中，与注射等渗盐水（0.2 ml）相比，引起了显著更高水平的疼痛峰值、疼痛持续时间和总体疼痛。此外，女性谷氨酸诱发的峰值和整体肌肉疼痛明显大于男性。在两种性别的大鼠中，谷氨酸（10穆尔，0.5 M）诱发活动的咬肌传入（n = 36），预计到亚核尾侧，一个重要的中继有害输入从颅面区域的亚群。对谷氨酸的最大反应记录在具有最慢传导速度（2.5-5 m/s）的肌肉传入中。此外，谷氨酸诱发的咬肌传入活动显着大于雌性大鼠。这些结果表明，谷氨酸注射到咬肌引起的疼痛反应，是女性比男性更大，这种差异的一个可能的机制可能是一个更大的敏感性，女性咬肌传入谷氨酸。这些与性别有关的急性实验性咬肌疼痛的差异是特别有趣的，因为许多慢性肌肉疼痛的患病率较高的妇女。
Animal studies have suggested that tissue injury-related increased levels of glutamate may be involved in peripheral nociceptive mechanisms in deep craniofacial tissues. Indeed, injection of glutamate (0.1-1 M, 10 mul) into the temporomandibular region evokes reflex jaw muscle responses through activation of peripheral excitatory amino acid receptors. It has recently been found that this glutamate-evoked reflex muscle activity is significantly greater in female than male rats. However, it is not known whether peripheral administration of glutamate, in the same concentrations that evoke jaw muscle activity in rats, causes pain in humans or activates deep craniofacial nociceptive afferents. Therefore we examined whether injection of glutamate into the masseter muscle induces pain in male and female volunteers and, since masseter afferent recordings were not feasible in humans, whether glutamate excites putative nociceptive afferents supplying the masseter muscle of male and female rats. Injection of glutamate (0.5 M or 1.0 M, 0.2 ml) into the masseter muscle of both men and women caused significantly higher levels of peak pain, duration of pain, and overall pain than injection of isotonic saline (0.2 ml). In addition, glutamate-evoked peak and overall muscle pain in women was significantly greater than in men. In rats of both sexes, glutamate (10 mul, 0.5 M) evoked activity in a subpopulation of masseter muscle afferents (n = 36) that projected to the subnucleus caudalis, an important relay of noxious input from the craniofacial region. The largest responses to glutamate were recorded in muscle afferents with the slowest conduction velocities (2.5-5 m/s). Further, glutamate-evoked masseter muscle afferent activity was significantly greater in female than in male rats. These results indicate that glutamate injection into the masseter muscle evokes pain responses that are greater in women than men and that one possible mechanism for this difference may be a greater sensitivity to glutamate of masseter muscle afferents in females. These sex-related differences in acute experimental masseter muscle pain are particularly interesting given the higher prevalence of many chronic muscle pain conditions in women.