| Objective:Modern medicine considers to think that the pain is a complex physiological and psychological activity, including the feeling of physical and psychological experience.There are two components of pain, sensory-discriminative and emotional-affective. In the past several decades, the studies on the former have made great progresses, but increasing attention on the latter, caused by harmful stimulation, malignant emotions such as fear,anxiety depression and irritability, is being attracted. Previous studies have found that anterior cingulate cortex(ACC), especially, rostral ACC(r ACC) plays an important role in pain-related emotional behavior. Electroacupuncture(EA) has been widely used in clinical chronic pain. Recently some clinical studies and animal experiments also have found that EA canrelieve the affective pain, but its mechanism is not clear. A novel electrophysiological method, in vivo multi-channel recording technique, can simultaneously record the electrical activity of a large number of neurons in awake rats.Here, we will investigate the relationship between the emotional responses and neurons firing in r ACC brain areas in rats, and explore the mechanism of EA for relieving pain emotion by the in vivo multi-channel recording technique.Methods:This study combines the literature of conditioned place avoidance model method and the experimental requirements, design is as follows: Electrode production, Electrode embedment, C-CPA, behavior-eletrophysiologycal. Experiment is divided into four major groups, n=6 each group rats. The first group in the general environment, we need toobserve the r ACC area electrical activity of neurons after one side of the foot injectioned of CFA/saline. The second group of rats after giving the soles of the feet after injection of CFA/saline, with "environment" pain coupling match, we record the electrical activity of the r ACC area neurons and behavior. The third ground of rats giving sole of the feet after injection of CFA/saline, then give the electroacupunture, with environment pain coupling match, we record the electrical activity of the r ACC area neurons and behavior. The fourth group of rats giving sole of the feet after injection of CFA/saline, with environment pain coupling match, then give the DAMGO, we record the electrical activity of the r ACC area neurons and behavior.Results:1. In the normal environment, CFA was administrated in subcutaneous injection. The r ACC area neuronal electrical activity(pre 0.273±0.496 imp/s VS post 0.648±2.266imp/s, P<0.05, n=26) and saline group(pre 0.220±0.272 imp/s VS post 0.183±0.422imp/s, P>0.05, n=19). There was significant difference before and after injection of CFA statistical significance, it suggested that the r ACC area was involved in coding the pain reaction process.2 After CFA injection, rats were conditioned with one side environment, neuronal activity on each sides of the environment(CFA-paired environment 0.853±1.377 imp/s VS non pain environment 0.221±0.971 imp/s, P<0.05, n=26), there was a statistically significant. Behavioral analysis showed(pre 303.55±61.77 s VS post 140.32±33.52 s,P<0.05, n=6), Behavioral responses also showed statistical significance; saline group(CFA-paired environment 0.545±0.621 imp/s VS non pain environment 0.555±0.709 imp/s,P>0.05,n=23), there was no significant statistical differences. Behavioral analysis showed(pre 281.40±58.74 s VS Post 279.30±55.99 s, P>0.05, n=6), there was no significant statistical differences.3 After CFA injection and EA stimulation in rats, rats were conditioned withone side environment, Neuronal activity on each side of the environment(CFA-pair d environment 0.113±0.265 imp/s VS non pain environment 0.088±0.393 imp/s, P>0.05, n=21); Behavioral analysis showed(pre 268.47±57.4s VS post 282.67±34.2s,P>0.05, n=6), there was no significant statistical differences. Saline group(saline-paire d environment 0.367±1.56 imp/s VS non pain environment 0.292±1.16 imp/s, P>0.05, n=20). Behavioral analysis showed(pre 255.40s±50.5s VS Post 304.48±58.5s, P>0.05, n=6), there was also no significant statistical differences. Electroacupuncture c ould relieve emotional pain by the inflammatory pain.4. After CFA injection, rats were conditioned with one side environment by i.t.DAMGO, Neuronal activity on each sides of the environment(CFA-paired environment0.225±1.31 imp/s VS non pain environment 0.248±0.478 imp/s, P<0.05, n=24), there was a statistical significance. Behavioral analysis showed( pre 296.07±35.5s VS post130.40±25.5s, P<0.05, n=6); Behavioral also was statistically significant. Saline group(CFA-paired environment 0.484±1.833 imp/s VS non pain environment0.516±1.397imp/s, P>0.05, n=15),there was no significant statistical differences. Behavioral analysis showed(pre 303.82±30.3s VS post 318.33±74.9s, P>0.05, n=6), there was no significant statistical differences.Conclusion:The results of CPA behavioral responses combined with in vivo multi-channel recording suggest:(1) the r ACC area is involved in the occurrence of emotional pain.(2)Electroacupuncture can relieve the affective pain through decreasing the neurons firing caused by harmful stimulation in r ACC. |
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