Skilling S R, Larson A A
Department of Veterinary PathoBiology, University of Minnesota, St. Paul 55108.
Neurosci Lett. 1993 Feb 5;150(1):107-11. doi: 10.1016/0304-3940(93)90119-6.
The origin of the excitatory amino acids (EAA) aspartate (Asp) and glutamate (Glu) released into the dorsal spinal cord extracellular fluid of rats following intradialysate infusion of substance P (SP) was studied using neonatal capsaicin, dorsal rhizotomy and proximal spinal cord transection. Neonatal capsaicin (50 mg/kg i.p.) had no effect on basal EAA release, but significantly inhibited SP-induced release of both Asp (86%) and Glu (70%). Bilateral dorsal rhizotomy enhanced SP-induced release of Asp (152%) and had no effect on Glu release compared to sham-operated controls. Proximal spinal transection (T8-9) had no effect on basal or SP-induced release of EAAs compared to sham-operated controls. The ability of neonatal capsaicin to inhibit, and dorsal rhizotomy to potentiate Asp release correlates well with their distinct effects on hyperalgesia and suggests that these manipulations do not produce identical lesions. Neonatal capsaicin likely interferes with the normal development of EAA interneurons innervated by SP primary afferent C-fibers. Rhizotomy may result in a compensatory up-regulation of SP receptors on EAA interneurons.
利用新生大鼠辣椒素处理、背根切断术和脊髓近端横断术，研究了在向大鼠脊髓背侧细胞外液中注入P物质（SP）后释放的兴奋性氨基酸（EAA）天冬氨酸（Asp）和谷氨酸（Glu）的来源。新生大鼠腹腔注射辣椒素（50mg/kg）对基础EAA释放无影响，但显著抑制SP诱导的Asp（86%）和Glu（70%）释放。与假手术对照组相比，双侧背根切断术增强了SP诱导的Asp释放（152%），而对Glu释放无影响。与假手术对照组相比，脊髓近端横断术（T8-9）对基础或SP诱导的EAA释放均无影响。新生大鼠辣椒素抑制和背根切断术增强Asp释放的能力与其对痛觉过敏的不同影响密切相关，表明这些操作不会产生相同的损伤。新生大鼠辣椒素可能会干扰由SP初级传入C纤维支配的EAA中间神经元的正常发育。背根切断术可能导致EAA中间神经元上SP受体的代偿性上调。
