Jin Y H, Nishioka H, Wakabayashi K, Fujita T, Yonehara N
Department of Pharmacology, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka 565-0871, Japan.
Neuroscience. 2006;138(4):1329-39. doi: 10.1016/j.neuroscience.2005.12.049. Epub 2006 Feb 10.
Behavioral evidence supports a role for peripheral glutamate receptors in normal nociceptive transmission. In this study, we examined the release of the excitatory amino acids, glutamate and aspartate, in the s.c. perfusate of the rat hind instep by in vivo microdialysis. Antidromic stimulation of the sciatic nerve and noxious stimuli in the form of heat stimulation and local application of capsaicin cream (1%) to the instep caused an increase in excitatory amino acid release. This capsaicin-induced excitatory amino acid release was suppressed by pretreatment with capsaicin. Both systemic (10 mg/kg, i.v.) and local injections (10(-5) M in the perfusate) of morphine inhibited the increase in excitatory amino acid release evoked by local application of capsaicin cream to the instep. This inhibitory effect of morphine was antagonized by naloxone either given systemically (5 mg/kg, i.v.) or locally (10(-5) M). These results suggest that excitatory amino acids are released from small diameter afferent fibers by heat stimulation in the periphery or local application of capsaicin cream, and that activation of opioid receptors, present on the peripheral endings of small-diameter afferent fibers, can regulate noxious stimulus-induced excitatory amino acid release.
行为学证据支持外周谷氨酸受体在正常伤害性感受传递中发挥作用。在本研究中，我们通过体内微透析法检测了大鼠后足背皮下灌流液中兴奋性氨基酸谷氨酸和天冬氨酸的释放情况。对坐骨神经进行逆向刺激以及以热刺激和向足背局部涂抹1%辣椒素乳膏的形式施加伤害性刺激，均导致兴奋性氨基酸释放增加。预先用辣椒素处理可抑制辣椒素诱导的兴奋性氨基酸释放。全身注射吗啡（10 mg/kg，静脉注射）和局部注射吗啡（灌流液中10(-5) M）均能抑制向足背局部涂抹辣椒素乳膏所引起的兴奋性氨基酸释放增加。吗啡的这种抑制作用可被全身（5 mg/kg，静脉注射）或局部（10(-5) M）给予的纳洛酮拮抗。这些结果表明，在外周，热刺激或局部涂抹辣椒素乳膏可使兴奋性氨基酸从小直径传入纤维释放，并且小直径传入纤维外周终末上存在的阿片受体激活后可调节伤害性刺激诱导的兴奋性氨基酸释放。
