Characteristics Of EP Receptors In Propofol-evoked Vascular Pain And Intervention Effects Of MGluR5 Antagonist

Objective: To observe the changes of electromyography of flexor reflex,receptor subtypes of prostaglandin E(EP)and their messenger ribonucleotide(mRNA)expression in the spinal cord caused by vascular pain of propofol injection.To investigate the effect of 2-methyl-6-phenyl pyrimidine(MPEP)as a kind of antagonists of metabotropic glutamate receptor 5(mGluR5)on electromyography of flexor reflex,prostaglandin E receptor subtypes and messenger ribonucleotide(mRNA)expression。Methods: Twelve male SD rats weighing 280-340 g were anaesthetized with urethane.About 1cm under the femoral arteryincision,the heparinized polyethylene catheter was heated to a suitable shape,then was inserted into the intersection about 1cm to the right femoral artery and superficial ventral tail artery.In the control group,saline and 1% of propofol solution were pumped into femoral artery with the speed of 0.4 ml min-1.in experiment group,after peritoneal injection of MPEP(20mg/kg)15min,the same saline and 1% of propofol solution were pumped.Both groups were detected the rear right side of the biceps femoris and semitendinosus EMG by using 23 G needle electrodeafter reperfusion one hour.Each EMG was recorded and the recording waveform was amplificated and thenanalyzed byplethysmograph waveform and waveform image analysis software.After the EMG detection,the rates were sacrificed by cervical and lumbar bulges at the spinal cord were collected.Samples were detected by western blot to study the expression of EP1,EP2,EP3 and EP4 antibodies.Then the protein expressions of EP1,EP2,EP3 and EP4 in the samples were detected by western blot.In addition,the use of efficient use of capillary electrophoresis to detect brain excitatory amino acids(glutamate,Glu)content,not in the control group and the treatment group were MPEP 0.4ml min-1 at a rate of injection,which MPEP treatment group(physiological saline group and propofol group),under the pre-peritoneal injection of MPEP,after injection of different liquid injection,the rats were decapitated,the brains quickly.Sampling time: 2min,5min,30 min sampling,10 rats each time.Results: Compared with the normal saline group,propofol group significantly decreased the reflex threshold(P<0.05)and reflex latency was significantly shortened(P<0.05);compared with the normal saline group,propofol group lumbar segment EP receptor subtype EP2 and EP4 receptor were significantly enhanced(P<0.05),and the two mRNA table Damien significantly increased(P<0.05).Compared with propofol group,MPEP pretreatment + propofol group EP2 and EP4 receptor content and expression were significantly decreased(P<0.05),the expression of EP2 and EP4 receptor mRNA were decreased,there were significant differences between two groups(P<0.05).Conclusion:Pain on injection of propofol is closely related to the increasing expression of EP receptor subtype EP2 and EP4 in the spinal cord.Antagonists of metabotropic glutamate receptor 5(mGluR5)can significantly decrease the pain on injection of propofol,which may achieve through inhibitting the expression of EP receptor subtype EP2 and EP4 in the spinal cord and decreasing their content.