N-methyl-d-aspartate

To study the influence of NMDA-NO system on central sensitization of spinal cord in rats, hindpaw withdrawal latency (HWL) was observed before and after intrathecal NMDA, MK801 and L-NAME in rats, and the contents of SP, CGRP and FOS in the dorsal horn of the spinal cord were detected in three kinds of pain models of rats using immunohistochemical techique.Method1. One hundred rats were randomly assigned to ten groups of ten (named G₁ G₁₀), agents of intrathecal administration in different groups were: â‘ normal saline 10μ1 in group G₁; â‘¡NMDA 0.01μg in group G₂; â‘¢NMDA 0.1μg in group G₃; â‘£NMDA 1.0μg in group G₄; ⑤NMDA 10μg in group G₅; â‘¥L-NAME 250μg in group G₆; ⑦L-NAME 250μg 10 minutes before administration of NMDA 1.0μg in group G₇; ⑧MK801 250μg in group G₈; ⑨MK801 250μg 10 minutes before administration of NMDA 1.0μg in group G₉; â‘©L-NAME 250μg plus MK801 250μg 10 minutes before administration of NMDA 1.0μg in group G₁₀. After intrathecal administration, HWL were measured with hot plate each every 5 minutes in the following 60 minutes, and the analgesia index (AI) was calculated subquently.2. One hundred and sixty rats were randomly assigned to sixteen groups of ten, the procedures of each group were: â‘ NS 50μl was subcutaneously injected to the center of left hindpaws, 24 hours later, the lumbar enlargement of spinal cord was removed (named group F_c); â‘¡After 1,4,8, 12 and 24 hours of injection of formalin, the lumbar enlargement was removed (named group F₁,F₄,F₈, F₁₂ and F₂₄, respectively); â‘¢ Intrathecal administration of MK801 25μg 15 minutes before injection of formalin, andthe lumbar enlargement was removed at 1, 4,8,12 and 24 hours later (named group FM₁, FM₄,FM₈, FM₁₂ and FM₂₄, respectively); â‘£ Intrathecal administration of L-NAME 250μg 15minutes before injection of formalin, and the lumbar enlargement was removed at 1,4, 8,12 and 24 hours later (named group FL₁,FL₄,FL₈,FL₁₂ and FL₂₄, respectively). In each group, the contents of SP, CGRP and FOS in the dorsal horn of the spinal cord were also observed at every time point.3. One hundred and sixty rats were randomly assigned to sixteen groups of ten, the procedures of each group were: â‘ The sciatic nerve was only exposed without ligation. Subquently, the lumbar enlargement of spinal cord was removed (named group C_c); â‘¡ The standard neuropathic model for chronic constriction injury (CCI) was made, and the lumbar enlargement were removed at 1, 3, 5, 7 and 14 days following operation...