The Effect Of Electroacupuncture At PC6 On Stress-Induced Autonomic And Neuroendocrine Responses

Objective:Stress triggers alterations in the autonomic and neuroendocrine systems,thereby accelerating the onset and progression of cardiovascular disease.By replicating the immobilization stress model,we observed the effects of acupuncture at Nei Guan(PC6)on heart rate(HR),heart rate variability(HRV),the levels of norepinephrine(NE)and epinephrine(E)in plasma,the levels of norepinephrine(NE)and acetylcholine(ACh)in heart,the relative expressions of tyrosine hydroxylase(TH),phosphorylated tyrosine hydroxylase(p-TH)and acetylcholinesterase(Ach E)in heart,the levels of adrenocorticotropic releasing hormone(CRH)in the hypothalamus,and the levels of cortisol(CORT)in plasma to investigate the effect of electroacupuncture(EA)at PC6 on stress-induced autonomic and neuroendocrine responses,thus providing some theoretical basis for clinical early detection and management of stress-induced cardiovascular diseases.Methods:Forty healthy adult male SD rats with body mass around 250-280 g were randomly allocated divided into four groups: normal group,model group(immobilization stress group),PC6 group(immobilization stress + EA at PC6 group)and tail group(immobilization stress + EA at tail group),10 rats in each group.The normal group was not treated in any way.The model was prepared using immobilization stress by placing the rats in a specially designed cylinder immobiliser with the limbs immobilized and kept immobile for 150 min.The PC6 and tail groups were connected to the electroacupuncture treatment apparatus at the beginning of the immobilization stress,with the parameters were set to 3 HZ,1m A,sparse and dense waves,and the intensity was appropriate for the rats’ limbs to tremble slightly.Changes in heart rate were recorded by electrocardiogram(ECG),heart rate variability(HRV)was used to analyse changes in cardiac autonomic activity,western blotting(WB)was used to detect changes in cardiac tyrosine hydroxylase(TH),phosphorylated tyrosine hydroxylase(pTH),choline acetylesterase(Ach E)and high performance liquid chromatography(HPLC)was used to analyse changes of norepinephrine(NE)and epinephrine(E)in plasma,NE and acetylcholine(ACh)in heart and cortisol(CORT)in plasma,and corticotropin-releasing hormone(CRH)in the paraventricular nucleus of the hypothalamus(PVN).Results:1.Heart rate and heart rate variability:(1)Rats in the model group displayed a significant increase in heart rate(p < 0.01),an increase in LF values(p < 0.05),a significant decrease in HF values(p < 0.01),and a significant increase in LF/HF values(p < 0.01)when compared to the normal group;(2)Rats in the PC6 group demonstrated a decrease in heart rate(p < 0.01),a significant increase in HF values(p < 0.01),and a significant decrease in LF/HF values(p < 0.01)and there was no significant difference in the tail group rats(p > 0.05)in comparison to the model group;(3)In the tail group,there was an increase in heart rate(p < 0.05),a significant increase in LF values(p <0.01),a significant decrease in HF values(p < 0.01),and a significant increase in LF/HF values(p < 0.01)in contrast to the group acting as PC6.2.Western Blot(1)Comparison between groups of rats with left heart TH,p-TH and ACh E:(1)The relative expressions of TH in the left heart of rats were not statistically significant in the normal,model,PC6,and tail groups(p > 0.05).(2)The relative expressions of p-TH were significantly higher and Ach E were significantly lower in the left heart of rats in the model group in comparison with the normal group(p < 0.01);(3)The relative expressions of p-TH were significantly lower and the relative expressions of Ach E were significantly higher(p < 0.01)in the left heart of rats in the PC6 group,and no significant differences were found in the rats of the tail group(p > 0.05)in comparison to the model group;(4)In the left heart of the rats in the tail group,there were no statistically significant differences in the relative expression of p-TH(p > 0.05)and a significant decrease in the relative expression of Ach E(p < 0.01)compared to the PC6 group.(2)Comparison between groups of rats with right heart TH,p-TH and Ach E :(1)The relative expressions of TH in the right heart of rats were not significantly different in the normal,model,PC6 and tail groups(p > 0.05).(2)In the model group,the relative expressions of p-TH in the right heart of rats were significantly higher than in the normal group(p < 0.01),while the relative expression of Ach E was decreased(p <0.01);(3)The relative expressions of p-TH in the right heart of rats in the PC6 group were decreased(p <0.05),the relative expressions of Ach E were significantly higher(p < 0.01)and no significant differences were found in the rats of the tail group(p >0.05)when compared to the model group;(4)In the right heart of rats in the tail group,the relative expressions of p-TH were not statistically significantly different(p > 0.05)and the relative expressions of Ach E were significantly lower(p < 0.01)compared to the PC6 group.3.HPLC(1)Comparison between the plasma NE and E of rats in each group:(1)The levels of NE in plasma increased significantly(p < 0.01)and the levels of E in plasma increased significantly(p < 0.01)in the model group when compared to the normal group;(2)The levels of NE decreased(p < 0.05)and the levels of E in plasma decreased significantly(p < 0.01)in the PC6 group,while there was no significant difference in the tail group(p > 0.05)in comparison to the model group;(3)The levels of NE increased(p < 0.05)and E in plasma increased significantly(p < 0.01)in the tail group as compared to the PC6 group.(2)Comparison between NE and ACh in the hearts of rats in each group:(1)The content of NE increased considerably(p<0.01)and ACh dropped significantly(p<0.01)in the left and right hearts of rats in the model group compared to the normal group;(2)The content of NE reduced considerably(p<0.01)and the content of ACh increased significantly(p<0.01)in the left and right hearts of rats in the PC6 group,and there was no significant difference between rats in the tail group(p > 0.05)compared to the model group;(3)The content of NE was raised(p < 0.05)and ACh was dramatically lowered(p < 0.01)in the left and right hearts of rats in the tail group as compared to the PC6 group.(3)Comparison between CRH in the PVN and plasma CORT of rats in each group:(1)The content of CRH in the PVN and CORT in plasma of rats in the model group was significantly increased(p < 0.01)when compared to the normal group;(2)The content of CRH in the PVN and CORT in the plasma of rats in the PC6 group decreased significantly(p < 0.01),and there was no significant difference between rats in the tail group(p > 0.05)in comparison to the model group;(3)The content of CRH in the PVN significantly increased(p < 0.01)and CORT in plasma was increased(p < 0.05)in the tail group as compared to the PC6 group.Conclusion:1.Electroacupuncture at PC6 can modulate stress-induced autonomic responses.2.Electroacupuncture at PC6 can modulate stress-induced neuroendocrine responses.