Experimental Study On The Effect Of Acupuncture On NF - κB, INOS And NO In Rats With Chronic Stress Depression

Objective:This study was to investigate the possible mechanism of acupuncture on depression in a chronic stress rat model of depression. We observed the behaviors and the key components of the NF-κB signal pathway including NF-κB, iNOS and NO in a chronic stress rat model of depression.Methods:1.36 Male SD rats were randomly divided into 4 groups:normal group, model group, acupuncture group and fluoxetine group.2. The chronic unpredictable mild stress (CUMS) rat model of depression was used in the study. Stressors include deprivation of food and water, damp bedding, cold water swimming, oscillation, clip and restraint. One stressor was given randomly daily for 28 days, and every stressor was used once a week.3. During the CUMS procedure, acupuncture treatment was given once every other day on "Baihui" and "Neiguan" before the stress and fluoxetine was given by oral administration once a day (10mg/kg) before the stress.4. The body weight, sucrose intake and open field test of rats were used to indicate the general condition, the anhedonia and locomotor activity behavior of the rats respectively.5. The NF-κB expression in hippocampus and frontal cortex were measured by Western blot. The iNOS expression in the hippocampus, frontal cortex and serum were detected by ELISA. And contents of NO in the hippocampus, frontal cortex and serum were measured by nitrate reduction method.Results:1. Effects of acupuncture on the behaviors of rats.(1) Body weight:Before the start of the experiments, the body weight of the rats had no significant difference between the groups (P>0.05). At the 7th,14th,21th,28th day of the experiment the weight of the model group were significantly decreased compared with the normal group (P<0.01). Compared with model group, at the 7th day, the body weight of the acupuncture group increased significantly (P<0.01) and lasted to the 28th day. And fluoxetine group increased significantly until the 28th day (P<0.01).(2) Sucrose intake test:Before the start of the experiment, the sucrose intake of the rats had no significant difference between the groups (P>0.05). At the end of the experiment, compared with the normal group, the sucrose intake of the model group was significantly decreased (P<0.01). Compared with the model group, the sucrose intake of the acupuncture group and the fluoxetine group was significantly increased (P<0.01,0.01).(3) Open field test:At the end of the experiment, compared with the normal group, both of the crossing numbers and rearing numbers in the model group were significantly decreased (P<0.05,0.05). Compared with model group, the rearing numbers in acupuncture and fluoxetine group was significantly increased (P<0.05,0.01) as well as the crossing numbers (P<0.01,0.01).2. Effects of acupuncture on NF-κB expression level in the hippocampus and frontal cortex.Compared with normal group, the expression level of NF-κB in model group was significantly increased in hippocampus and frontal cortex (P<0.01). Compared with the model group, the expression level of NF-κB in the acupuncture group were significantly decreased in hippocampus and frontal cortex (P<0.05,0.01). Compared with the model group, the expression level of NF-κB in the Fluoxetine group were significantly decreased in hippocampus and frontal cortex (P<0.01,0.01).3. Effects of acupuncture on iNOS expression in the hippocampus, frontal cortex and serum.Compared with normal group, the expression of iNOS expression in the model group was significantly increased in hippocampus and frontal cortex (P<001,0.01). Acupuncture treatment significantly decreased iNOS expression in hippocampus and frontal cortex compared with the model group (P<0.01,0.01) as well as fluoxetine treatment (P<0.01,0.01).Compared with normal group, the expression of iNOS expression in the serum of the model group had no significant differences (P>0.05). Effect of acupuncture treatment on iNOS expression in the serum had no significant differences compared with the normal group (P>0.05) as well as fluoxetine treatment (P>0.05).4. Effects of acupuncture on NO contents in the hippocampus, frontal cortex and serum.Compared with normal group, the expression of NO expression in the model group was significantly increased in hippocampus, frontal cortex and serum (P<0.01,0.01,0.01). Acupuncture treatment significantly decreased NO contents in hippocampus, frontal cortex and serum compared with the model group (P<0.01,0.01,0.01), as well as fluoxetine treatment (P<0.01,0.01,0.01).Conclusions:1. Chronic stress significantly decreased the weight, the sucrose intake and the locomotivity, which suggested the model of depression was successful. The depressive behaviors could be improved by acupuncture and fluoxetine treatment. And in the aspect of improving weight, the onset time of acupuncture was earlier than fluoxetine.2. The increase of NF-κB, iNOS, NO in the rats’ hippocampus and frontal cortex induced by CUMS could be reversed by acupuncture and fluoxetine treatment.3. Acupuncture could inhibit the key components of NF-κB signaling pathway (NF-κB, iNOS, NO) in the hippocampus and frontal cortex, which may partly mediate the antidepressant effect of acupuncture and fluoxetine through decreasing the inflammatory injury to the brain.Our study futher confirmed that immune inflammatory response was one of the important mechanisms of the pathogenesis of depression. And we found that acupuncture alleviated the inflammatory response through inhibiting the NF-κB signaling pathway, which may mediate the antidepressant effect of acupuncture. This will improve scientific connotation in acupuncture refreshing brain method, and lay the foundation for further understanding the mechanism of acupuncture treatment of depression.