谷氨酸钠对大鼠背部皮神经传入放电的影响

Effects of glutamate on the afferent discharges of dorsal cutaneous sensory nerves in rats

目的 探讨谷氨酸对大鼠背部皮神经自发传入放电的影响。方法 采用体内分离脊神经背侧皮支单纤维记录方法,在皮神经感受野注射谷氨酸受体的激动剂谷氨酸钠(0. 3mmol/L, 10μl),观察对皮肤感觉神经传入放电的影响及时程变化。结果 将谷氨酸钠注射入Aδ和C类感受单位的感受野,注射过程中(7min)和注射后(10min)每分钟的平均传入放电数与注药前比较均显著增加(P<0. 05 )。但Aβ感受单位注射过程中和注射后平均传入放电数与给药前相比无显著性差异(P>0. 05)。同时还发现谷氨酸钠对Aδ和C类初级传入末梢的兴奋作用可见于所观察的整个时段。结论 谷氨酸可能参与外周痛敏化过程。

Objective To observe the effects of glutamate on the afferent discharges of dorsal cutaneous sensory nerves in rats. Methods By using the single unit recording on isolated nerve filaments in the spinal nerve dorsal cutaneous branches in vivo , the effects of glutamate injection into the cutaneous receptive field of sensory nerves on primary afferent discharges were observed. Results Injection of 10 μl monosodium glutamate (0.3 mmol/L), a glutamate receptor agonist, significantly increased the mean discharge rate of Aδ and C units either during 7 min injection or 10 min post-injection as compared with pre-injection group ( P< 0.05), but did not affect the afferent discharge rate of the Aβ units ( P >0.05). The glutamate excitatory effects on the discharge rate of Aδ and C primary afferent terminal covered over all periods observed. Conclusion Glutamate, as a neurotransmitter, may be involved in the peripheral sensitization of pain.