Sorkin L S, McAdoo D J
Marine Biomedical Institute, University of Texas Medical Branch, Galveston 77550-2772.
Brain Res. 1993 Apr 2;607(1-2):89-98. doi: 10.1016/0006-8993(93)91492-b.
Several amino acids including aspartate, glutamate and glycine and the monoamine serotonin were retrieved from the extracellular space of the dorsal horn of the lumbar spinal cord in the alpha-chloralose anesthetized cat in vivo using a transverse microdialysis probe. Neurotransmitter concentrations were determined using high pressure liquid chromatography in combination with fluorescence (amino acid) or electrochemical (serotonin) detection. Intradermal injection of 3% capsaicin into the hindleg either ipsilateral or contralateral to the dialysis probe was used to evoke release. Extracellular concentrations of aspartate, glutamate and serotonin increased significantly following capsaicin injection into the ipsilateral limb. An almost equal increase in serotonin and a less pronounced, but still significant, increase in aspartate accompanied contralateral capsaicin injection. Glutamate concentrations increased in the dialysate during contralateral capsaicin injection in about half of the animals. These data are consistent with the hypothesis that Asp and Glu are both neurotransmitters released from nociceptive primary afferent fibers and/or interneurons activated by these fibers. In addition, Asp is presumed to be released from intrinsic spinal or descending systems following nociceptive stimulation. Bilateral release of 5HT into the dorsal horn most likely results from non-topographic activation of descending endogenous analgesia pathways.
在体内，使用横向微透析探针从α-氯醛糖麻醉的猫的腰脊髓背角细胞外空间中获取了包括天冬氨酸、谷氨酸、甘氨酸在内的几种氨基酸以及单胺血清素。使用高压液相色谱结合荧光（氨基酸）或电化学（血清素）检测来测定神经递质浓度。向与透析探针同侧或对侧的后肢皮内注射3%辣椒素以诱发释放。向同侧肢体注射辣椒素后，细胞外天冬氨酸、谷氨酸和血清素的浓度显著增加。对侧注射辣椒素后，血清素几乎等量增加，天冬氨酸增加不太明显但仍显著。在大约一半的动物中，对侧注射辣椒素期间透析液中谷氨酸浓度增加。这些数据与以下假设一致：天冬氨酸和谷氨酸都是从伤害性初级传入纤维和/或被这些纤维激活的中间神经元释放的神经递质。此外，推测天冬氨酸是在伤害性刺激后从脊髓固有或下行系统释放的。5-羟色胺双侧释放到背角很可能是由于下行内源性镇痛途径的非拓扑激活所致。
