Teoh H, Malcangio M, Fowler L J, Bowery N G
Department of Pharmacology, School of Pharmacy, London, UK.
Eur J Pharmacol. 1996 Apr 29;302(1-3):27-36. doi: 10.1016/0014-2999(96)00052-0.
In vitro superfusion release experiments and autoradiography were carried out on spinal cords of neonatally capsaicin-treated rats. Electrical and chemical stimulations significantly increased the release of aspartate, glutamate and gamma-aminobutyric acid (GABA) from hemisected dorsal horn slices of vehicle-treated animals. In capsaicin-treated rats, the evoked release of aspartate, glutamate and substance P but not GABA, were significantly lower. Capsaicin (1 microM) stimulated the release of aspartate and glutamate, as reported for substance P, in control slices but this effect was not as apparent in tissues from capsaicin-treated rats. Evoked GABA release was not affected in either case. alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), kainate, dizocilpine and GABAB binding sites were highly localised in the substantia gelatinosa. Capsaicin treatment did not affect the affinity of the binding sites in all four cases but significantly reduced the density of kainate, dizocilpine and GABAB binding sites. The data suggest that capsaicin-sensitive primary afferent fibres release aspartate, glutamate and Substance P following high-intensity stimulations and that this release might be modulated by presynaptic glutamate and GABAB receptors present on these terminals.
对新生期用辣椒素处理的大鼠脊髓进行了体外灌流释放实验和放射自显影。电刺激和化学刺激显著增加了用溶剂处理动物的半横断背角切片中天冬氨酸、谷氨酸和γ-氨基丁酸（GABA）的释放。在辣椒素处理的大鼠中，天冬氨酸、谷氨酸和P物质的诱发释放显著降低，但GABA的诱发释放未受影响。如P物质那样，辣椒素（1微摩尔）在对照切片中刺激了天冬氨酸和谷氨酸的释放，但在辣椒素处理大鼠的组织中这种作用不明显。两种情况下诱发的GABA释放均未受影响。α-氨基-3-羟基-5-甲基-4-异恶唑丙酸（AMPA）、海人酸、地佐环平以及GABAB结合位点高度定位于胶状质。辣椒素处理在所有四种情况下均未影响结合位点的亲和力，但显著降低了海人酸、地佐环平以及GABAB结合位点的密度。数据表明，辣椒素敏感的初级传入纤维在高强度刺激后释放天冬氨酸、谷氨酸和P物质，并且这种释放可能受到这些终末上突触前谷氨酸和GABAB受体的调节。
