The Different Dopamine Receptors In BLA Brain Region Involved In The Regulation Mechanism Of Negative Emotion Induced By Chronic Pain And Electroacupuncture Intervention

[Objective]Pharmacological and behavioral methods were used to regulate dopamine receptor D1（DRD1）and dopamine receptor D2（DRD2）in basolateral amygdala（BLA）under physiological and pathological conditions,respectively.To observe the effects of BLA brain DRD1 and DRD2 on mechanical pain threshold and negative emotion in mice,and whether electroacupuncture（EA）can intervene chronic pain and negative emotion through BLA brain DRD1 and DRD2.[Methods]The experiments were divided into 3 parts.Part one:To observe the relationship between different dopamine receptors in amygdala（AMY）brain region and negative emotion induced by chronic neuropathic pain model mice and electroacupuncture intervention.SNI model mice underwent selective sciatic nerve injury（SNI）on the left hind foot and were stimulated by 100 Hz EA at bilateral "Zusanli（ST36）" and "Sanyinkou（SP6）".Mechanical pain measurement was used to detect paw withdrawal thresholds（PWTs）in mice,and elevated plus maze test（EPM）and open field test（OFT）were used to detect anxiety-like behaviors.Western blotting（WB）was used to detect the expression changes of DRD1 and DRD2 in AMY brain region in SNI group and SNI+EA group.Part two:Regulation of DRD1 in BLA brain region on mechanical pain threshold and negative emotion in mice in physiological and pathological states and electroacupuncture intervention.Part three:Regulation of DRD2 in BLA brain region on mechanical pain threshold and negative emotion in mice in physiological and pathological states and electroacupuncture intervention.[Results]Part one:Compared with Sham group,the PWTs of SNI model mice decreased significantly 7 days after modeling and lasted for at least 14 days（P<0.05）and anxiety-like behaviors were observed at 15 and 17 days after model（P<0.05）,indicating that the SNI pain emotion model was successfully established.Compared with SNI group,the PWTs in SNI+EA group were significantly increased 14 days after model（P<0.05）,and anxiety-like behaviors was significantly relieved（P<0.05）.Compared with SNI+Sham EA group,SNI+EA group could alleviate PWTs and anxiety-like behaviors（P<0.05,P<0.05）.WB results showed that compared with Sham group,DRD1 expression decreased and DRD2 expression increased in AMY brain region of SNI group（P<0.05）.Compared with SNI group,DRD1 expression increased and DRD2 expression decreased in SNI+EA group,（P<0.05）.Part two:（1）In physiological state,there was no statistical difference in PWTs between Naive+Vehicle group,Naive+DRD1 antagonist group,Naive+DRD1 antagonist+agonist group and Naive+DRD1 antagonist+EA group at 7 d and 14 d（P>0.05）.Behavioral results showed that compared with Naive+Vehicle group,Naive+DRD1 antagonist group had anxiety-like behaviors（P<0.05）.Compared with Naive+DRD1 antagonist group,anxiety-like behaviors was relieved in both Naive+DRD1 antagonist+agonist group and Naive+DRD1 antagonist+EA group（P<0.05）.（2）In pathological state,compared with Sham+Vehicle group,PWTs in SNI+Vehicle group decreased on day 14（P<0.05）.Compared with SNI+Vehicle group,PWTs in SNI+DRD1 agonist group were not significantly improved（P>0.05）,while PWTs in SNI+Vehicle+EA group were significantly improved（P<0.05）.Compared with SNI+DRD1 agonist group,PWTs in SNI+DRD1 agonist+EA group were significantly increased（P<0.05）.Behavioral results showed that compared with Sham+Vehicle group,SNI+Vehicle group showed anxiety-like behaviors（P<0.05）.Compared with SNI+Vehicle group,anxiety-like behaviors was relieved in SNI+DRD1 agonist group and SNI+Vehicle+EA group（P<0.05）.There was no statistical difference between SNI+DRD1 agonist+EA group and SNI+DRD1 agonist group（P>0.05）.Part three:（1）In physiological state,there was no significant difference in PWTs between Naive+Vehicle group,Naive+DRD2 agonist group,Naive+DRD2 agonist+antagonist group,and Naive+DRD2 agonist+EA group at 7 d and 14 d（P>0.05）.Behavioral results showed that compared with Naive+Vehicle group,Naive+DRD2 agonist group had anxiety-like behaviors（P<0.05）.Compared with Naive+DRD2 agonist group,anxiety-like behaviors was relieved in both Naive+DRD2 agonist+antagonist group and Naive+DRD2 agonist+EA group（P<0.05）.（2）In pathological state,14 days after SNI modeling,PWTs in SNI+vehicle group decreased continuously compared with Sham+Vehicle group（P<0.05）.Compared with SNI+Vehicle group,PWTs in SNI+DRD2 antagonist group were not significantly improved（P>0.05）,while PWTs in SNI+Vehicle+EA group was significantly increased.Compared with SNI+DRD2 antagonist group,SNI+DRD2 antagonist+EA group was significantly increased（P<0.05）.Behavioral results showed that compared with Sham+Vehicle group,SNI+Vehicle group showed anxiety-like behaviors（P<0.05）.Compared with SNI+Vehicle group,the anxiety-like behaviors of SNI+DRD2 antagonist group and SNI+Vehicle+EA group was relieved（P<0.05）.There was no significant difference between SNI+DRD2 antagonist+EA group and SNI+DRD2 antagonist group（P>0.05）.[Conclusion]1.SNI model can reduce mechanical pain threshold and induce anxiety-like behaviors.100 Hz EA can significantly increase mechanical pain threshold and alleviate anxiety-like behaviors in SNI model mice.2.In physiological state,antagonizing DRD1 or activating DRD2 in BLA brain region induced anxiety-like behaviors in Naive mice.In pathological state,activating DRD1 or antagonizing DRD2 in BLA brain region can effectively relieve anxiety-like behaviors in SNI mice,but mechanical pain threshold is not affected.EA can relieve anxiety-like behaviors by up-regulating DRD1 or down-regulating DRD2 in BLA brain region.