ABSTRACT
ObjectiveTo observe the changes in the expression and distribution of G protein-gated inwardly rectifying potassium channel subunit 2 （GIRK2） in the dorsal root ganglion （DRG） and spinal cord dorsal horn of rats with remifentanil-induced hyperalgesia. MethodsHyperalgesia was induced by intravenous infusion of remifentanil 4 μg/kg/min for 2 h in adult male SD rats. At 6th hour and on days 1， 3 and 5 following remifentanil treatment， we used immunofluorescence to examine the changes in the GIRK2 distribution and expression. Immunoblotting was used to detect GIRK2 expression of the total protein and membrane protein in DRG and spinal dorsal horn of rats. Behavioral testing was applied to evaluate the effect of intrathecal injection of GIRK2-specific agonist ML297 on thermal nociceptive threshold on day 1 after remifentanil infusion. Resultsmmunofluorescence results showed that GIRK2 was mainly co-localized with IB4-positive small neurons in DRG and nerve fibers in spinal dorsal horn. GIRK2 expression was significantly downregulated following remifentanil treatment. Immunoblotting results revealed that on day 1 following intravenous infusion of remifentanil， compared with those in the control group， GIRK2 expression levels of the total protein and membrane protein in DRG （0.47 ± 0.10 vs. 1.01 ± 0.17， P < 0.001； 0.47 ± 0.11 vs. 1.06 ± 0.12， P < 0.001） and spinal dorsal horn （0.52 ± 0.09 vs. 1.10 ± 0.08， P < 0.001； 0.54 ± 0.10 vs. 1.01 ± 0.13， P < 0.001） were all significantly decreased. The behavioral results showed that intrathecal ML297 effect on thermal withdrawal latency was significantly reduced following remifentanil treatment （P < 0.001）. ConclusionsRemifentanil might induce hyperalgesia via down-regulating GIRK2 expression in rat DRG and spinal cord dorsal horn.
ABSTRACT
remifentanil；hyperalgesia；CCL2；microglia@#【Objective】To observe C-C motif chemokine ligand 2（CCL2）mediates remifentanil-induced hyperalgesia by activating microglia in rats.【Methods】Thirty-six adult male SD rats were equally and randomly divided into 6 group with 6 rats in each group：normal saline ，remifentanil，saline + intrathecal injection of phosphate buffer saline（PBS）， remifentanil + intrathecal injection of PBS，saline + intrathecal injection of CCL2 neutralizing antibody and remifentanil + CCL2 neutralizing antibody. To establish remifentanil-induced hyperalgesia model，remifentanil［4 μg/ （kg·min）2 h］ was continuously infused into rats via the tail vein. Then ，immunofluorescence and western blot were performed to examine the expression of spinal CCL2 in rats. Thirty minutes before remifentanil infusion，intrathecal injection of CCL2 neutralizing antibody was performed to observe remifentanil-induced hyperalgesia and the effect on the activation of microglial in the spinal cord of rats.【Results】Compared with the normal saline group，the thermal and mechanical pain thresholds in the remifentanil group were significantly reduced（P < 0.05）. The expression of protein（0.66 ± 0.071 vs. 0.18 ± 0.04；P < 0.001）and average immunofluorescence density of spinal CCL2（0.170 ± 0.009 vs. 0.047 ± 0.006；P < 0.001）were significantly increased on the first day after remifentanil infusion. Prior intrathecal injection of CCL2 neu⁃ tralizing antibody not only inhibited remifentanil-induced activation of microglia in the spinal cord（P < 0.001），but also mitigated remifentanil-induced thermal hyperalgesia and mechanical pain sensitivity（P < 0.05）.【Conclusion】CCL2 me⁃ diates the remifentanil-induced hyperalgesia by activating spinal microglia in rats.
ABSTRACT
P13-OMP (29.1). P13-OMP and OMP68 group challenged with P13 and P11 can be efectivly protected; P13-WCB group challenged with P13 and P11 can not be efectivly protected; the control group were died out. The P13-OMP and OMP68 of Bordetella bronchiseptica has good immunogenicity and protection, so the results of this study lay good theoretical foundation for OMP subunit vaccine.