ABSTRACT
Objective To evaluate the relationship between p38 mitogen-activated protein kinase (p38MAPK) and G protein-coupled receptor kinase 2 (GRK2) in the development of persistent postoperative pain in rats.Methods Pathogen-free healthy male Sprague-Dawley rats,weighing 200-250 g,aged 2 months,were used in this study.Sixty rats in which intrathecal catheters were successfully implanted were divided into 6 groups (n =10 each) using a random number table method:sham operation group (group S),sham operation plus dimethyl sulfoxide (DMSO) group (group D),sham operation plus GRK2 degradation inhibitor MDL28170 group (group M),persistent postoperative pain group (group PPP),persistent postoperative pain plus DMSO group (group PPP+D) and persistent postoperative pain plus MDL28170 group (group PPP+M).Persistent postoperative pain was evoked by skin/muscle incision and retraction (SMIR).Immediately after operation and at 1,2 and 3 days after operation,normal saline 20 μl was intrathecally injected once a day in S and PPP groups,5％ DMSO 10 μl was intrathecally injected once a day in D and PPP+D groups,and MDL28170 10 μl (50 μg) was intrathecally injected once a day in M and PPP+M groups.The mechanical paw withdrawal threshold (MWT) was measured at 1 day before operation and 3,7,14 and 21 days after operation (T1-4).Four rats in each group were selected after behavioral testing at T3 and sacrificed,and the L4-6 segments of the spinal cord were removed for determination of the expression of phosphorylated p38MAPK (p-p38MAPK) by Western blot.Results There was no significant difference in MWT at each time point or expression of p-p38MAPK among group S,group D and group M (P＞0.05).Compared with group S,the MWT was significantly decreased,and the expression of p-p38MAPK was up-regulated in PPP,PPP+D and PPP +M groups (P＜ 0.05).Compared with group PPP,the MWT was significantly increased,and the expression of p-p38MAPK was down-regulated in group PPP+M (P＜0.05),and no significant change was found in the MWT or expression of p-p38MAPK in group PPP+D (P＞0.05).Conclusion Down-regulated expression of spinal GRK2 can promote the activation of p38MAPK in the spinal cord and is involved in the development of persistent postoperative pain in rats.
ABSTRACT
Objective@#To evaluate the relationship between p38 mitogen-activated protein kinase (p38MAPK) and G protein-coupled receptor kinase 2 (GRK2) in the development of persistent postoperative pain in rats.@*Methods@#Pathogen-free healthy male Sprague-Dawley rats, weighing 200-250 g, aged 2 months, were used in this study.Sixty rats in which intrathecal catheters were successfully implanted were divided into 6 groups (n=10 each) using a random number table method: sham operation group (group S), sham operation plus dimethyl sulfoxide (DMSO) group (group D), sham operation plus GRK2 degradation inhibitor MDL28170 group (group M), persistent postoperative pain group (group PPP), persistent postoperative pain plus DMSO group (group PPP+ D) and persistent postoperative pain plus MDL28170 group (group PPP+ M). Persistent postoperative pain was evoked by skin/muscle incision and retraction (SMIR). Immediately after operation and at 1, 2 and 3 days after operation, normal saline 20 μl was intrathecally injected once a day in S and PPP groups, 5% DMSO 10 μl was intrathecally injected once a day in D and PPP+ D groups, and MDL28170 10 μl (50 μg) was intrathecally injected once a day in M and PPP+ M groups.The mechanical paw withdrawal threshold (MWT) was measured at 1 day before operation and 3, 7, 14 and 21 days after operation (T1-4). Four rats in each group were selected after behavioral testing at T3 and sacrificed, and the L4-6 segments of the spinal cord were removed for determination of the expression of phosphorylated p38MAPK (p-p38MAPK) by Western blot.@*Results@#There was no significant difference in MWT at each time point or expression of p-p38MAPK among group S, group D and group M (P>0.05). Compared with group S, the MWT was significantly decreased, and the expression of p-p38MAPK was up-regulated in PPP, PPP+ D and PPP+ M groups (P<0.05). Compared with group PPP, the MWT was significantly increased, and the expression of p-p38MAPK was down-regulated in group PPP+ M (P<0.05), and no significant change was found in the MWT or expression of p-p38MAPK in group PPP+ D (P>0.05).@*Conclusion@#Down-regulated expression of spinal GRK2 can promote the activation of p38MAPK in the spinal cord and is involved in the development of persistent postoperative pain in rats.
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Objective To explore the protective effects of erythropoietin (EPO) on cardiomyocytes against hypoxia/reoxygenation (HR) injury. Method Isolated and cultured rat eardiomyocytes were subjected to 2-hour hypoxia followed by 1 hour reoxygenation to establish model of HR injury. Cardiomyocytes were randomly divided into 4 groups: sham group, HR group, HR + EPO-treated group (EPO 10 U/ml), and HR + EPO + UO126-treated group (U0126 10?mol/L). The concentration of lactate dehydrogenase (LDH) in culture medium was detected by automatic biochemical analyzer; viability of eardiomyocytes was measured by MTT assay; apoptosis ratio was determined by TUNEL technology and Annexin-V-FITC with flow cytometer (FCM); level of extracellular signal- regulated kinase 1/2 (ERK_(1/2)) and phospho-ERK_(1/2) were measured by Western-blot analysis. Results EPO significantly decreased the leakage of LDH, enhanced activity, reduced apoptosis ratio, and increased level of phospho-ERK_(1/2).However, the effects were blocked by U0126, an inhibitor of MAPK. Conclusions EPO has the protective effects on cardiomyocytes against HR injury possibly via the mechanism of activation of ERK_(1/2) and inhibition of apoptosis.
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AIM: To study the effects of low density lipoproteins (LDLs) on insulin-like growth factor-1 receptor (IGF-1R), phosphorylated extracellular signal-regulated kinase (p-ERK), Bcl-2 and Bax protein expression in mouse peritoneal macrophages (MPMs). METHODS: Using the methods of immunocytochemistry and Western blotting, the expression of IGF-1R, p-ERK, Bcl-2 and Bax protein in MPMs treated with LDLs, anti-IGF-1R antibody (?-IR-3) or ERK inhibitor (PD98059) were detected. RESULTS: oxLDL significantly increased the IGF-1R protein expression in a dose and time-dependent manner. P-ERK protein expression induced by oxLDL peaked at 5 min. Moreover, oxLDL could induced ERK translocation from cytoplasm to nuclear. When given ?-IR-3, p-ERK protein expression was significantly inhibited, and ERK translocation disappeared. oxLDL increased Bcl-2 protein expression and reduced Bax expression in a dose and time-dependent manner. When given PD98059, Bcl-2 and Bax protein expression induced by oxLDL altered significantly. Native LDL had no significant effect on the expression of these four proteins. CONCLUSIONS: oxLDL may promote cultured MPMs survival at least by enhancing IGF-1R expression and ERK phosphorylation, and there may be many pathways involved in MPMs survival induced by oxLDL, Whereas native LDL had no effects on culture MPMs.