μ阿片受体外显子7在大鼠EM-1镇痛中的作用
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摘要
目的:研究μ阿片受体外显子-7在EM-1镇痛中的作用。方法:取大鼠鞘内置管成功造模,随机分为3组,对照组,N-siRNA组及E-siRNA组,每组8只,每组分别经鞘内给予生理盐水30μl,阴性siRNA20μl质粒(NsiRNA组),或阳性siRNA 20μl质粒(E-siRNA组),连续处理3d,每天一次,于第4天检测机械痛觉,在基础机械痛阈检测后1h注射药物,大鼠分别于鞘内注射10μg的EM-1,于药物注射后5min,20min,40min及60min时间点检测机械性缩足反射痛阈值。E-siRNA组在上述实验结束6h后给予EM-1,10μg加10μg的纳洛酮,重复5min,20min,40min时间点检测痛阈值。结果:各组间的基础机械痛阈无差别;E-siRNA组EM-1的镇痛效能未降低(P>0.05),但表现延迟现象,在20min时达到最大;E-siRNA组在EM-1加纳洛酮未显示镇痛作用。结论:鞘内注射的靶向μ阿片受体外显子-7的阳性siRNA,对基础机械痛阈无影响;对EM-1的镇痛作用有延迟作用但未降低其镇痛效能。
Objective:To research the influence of exon 7ofμopioid receptor gene on analgesic effect induced by endomorphin-1(EM-1).Methods:A total of 24 SD ratsimplanted chronically with PE10 lumbar intrathecal catheters according to zhang and examined without histological abnormalities were randomly divided into three groups,control group(n=8),sham siRNA group(n=8),and siRNA group(n=8).Rats were respectively administrated with 30μl saline solution in control group,20μl siRNA plus 10μl lipofectamine 2000 in siRNA group,or 20μl sham siRNA plus 10μl lipofectamine 2000 in sham siRNA group through intrathecal injection one time every day for three consecutive days.On the fourth day,1hafter testing the basicmechanical pain threshold,each group was individually administrated with EM-1 10μg intrathecally.Then,The pain thresholds of mechanical paw withdrawal were detected at time points of 5min,20 min,40min,60 min after drug injection.After 6hof the examination of pain threshold,the siRNA groups were administrated with 10μg EM-1plus 10 ug naloxone,paw withdrawal mechanical pain thresholds were repeatedly detected at 5 min,20 min,40 min after drug injection.Results:There were nodifferences in the basic mechanical pain threshold among the three groups(P>0.01).The analgesic effect induced by EM-1reached maximal level at 5min after drug injection in the control group and the sham group.The maximal analgesic level induced by EM-1were delayed to 20 min post injection in the siRNA group,but the analgesic effect induced by EM-1in the siRNA group showed no significant differenceas compared with that in the control group or the sham group(P>0.01).Then,naloxone blocked the analgesic effect induced by EM-1in siRNA groups.Conclusion:Positive siRNA targeted to exon 7ofμopioid receptor gene through intrathecal injection had no effect on the basic pain threshold and could not reduce analgesic effect induced by EM-1,but delayed the analgesic effect of EM-1.
Objective:To research the influence of exon 7ofμopioid receptor gene on analgesic effect induced by endomorphin-1(EM-1).Methods:A total of 24 SD ratsimplanted chronically with PE10 lumbar intrathecal catheters according to zhang and examined without histological abnormalities were randomly divided into three groups,control group(n=8),sham siRNA group(n=8),and siRNA group(n=8).Rats were respectively administrated with 30μl saline solution in control group,20μl siRNA plus 10μl lipofectamine 2000 in siRNA group,or 20μl sham siRNA plus 10μl lipofectamine 2000 in sham siRNA group through intrathecal injection one time every day for three consecutive days.On the fourth day,1hafter testing the basicmechanical pain threshold,each group was individually administrated with EM-1 10μg intrathecally.Then,The pain thresholds of mechanical paw withdrawal were detected at time points of 5min,20 min,40min,60 min after drug injection.After 6hof the examination of pain threshold,the siRNA groups were administrated with 10μg EM-1plus 10 ug naloxone,paw withdrawal mechanical pain thresholds were repeatedly detected at 5 min,20 min,40 min after drug injection.Results:There were nodifferences in the basic mechanical pain threshold among the three groups(P>0.01).The analgesic effect induced by EM-1reached maximal level at 5min after drug injection in the control group and the sham group.The maximal analgesic level induced by EM-1were delayed to 20 min post injection in the siRNA group,but the analgesic effect induced by EM-1in the siRNA group showed no significant differenceas compared with that in the control group or the sham group(P>0.01).Then,naloxone blocked the analgesic effect induced by EM-1in siRNA groups.Conclusion:Positive siRNA targeted to exon 7ofμopioid receptor gene through intrathecal injection had no effect on the basic pain threshold and could not reduce analgesic effect induced by EM-1,but delayed the analgesic effect of EM-1.
引文
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[3]Marrone GF,Lu Z,Rossi G,et al.Tetrapeptide dedomorphin analogs requre both full length and truncated splice variants of the mu opioid receptor gene Oprm1for analgesia[J].ACS Chem Neurosci,2016 Sep 20[Epub ahead of print].
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[2]De Marco R,Janecka A.Strategies to improve bioavailability and in vivo efficacy of the endogenous opioid peptides endomorphin-1and endomorphin-2[J].Curr Top Med Chem,2015,16(2):141-155.
[3]Marrone GF,Lu Z,Rossi G,et al.Tetrapeptide dedomorphin analogs requre both full length and truncated splice variants of the mu opioid receptor gene Oprm1for analgesia[J].ACS Chem Neurosci,2016 Sep 20[Epub ahead of print].
[4]Marrone GF,Grinnell S,Lu Z,et al.Truncated mu opioid GPCR variant involvement in opioid-dependent and opioid-dependent and opioid-independent pain modulatory systems within the CNS[J].PNAS,2016,113(13):3 663-3 668.