Effect of electroacupuncture on expression of NR2B in prefrontal cortex in morphine-withdrawal rats

ObjectiveTo observe the effect of electroacupuncture (EA) on learning and memory abilities and expression of N-methyl-D-aspartate receptor subunit (NR2B) in prefrontal cortex in morphine-withdrawal rats and to investigate the molecular biological mechanisms.MethodsThirty-six male SD rats were randomly divided into four groups, namely control group (group A), model group (group B), model with acupuncture group (group C) and model with electroacupunture group (group D), with 9 in each group. All rats except those in group A were subcutaneously injected with morphine hydrochloride injectio on the back with daily dosage increased day by day. Naloxone was given 3 h after the last injection to establish the models of morphine-withdrawal rats. After the models were established, the rats were treated with acupuncture and electroacupuncture respectively at bilateral “Shènshū”( BL 23) and “Zúsānli”( ST 36) for 15 min per time, once daily for 6 days. Space learning and memory abilities of the rats were measured by Morris water maze, and protein and gene expression levels of NR2B in prefrontal cortex were measured by Western Blot and RT-PCR.ResultsIn place navigation test, the escape latency in group B, group C and group D was significantly prolonged compared with that of group A (P<0.01), the escape latency in group C and group D was significantly shortened compared with that of group B (P<0.01) and the escape latency in group D was significantly shortened compared with that of group C (P<0.05); during spatial probe test, the number of times crossing the platform of group B, group C and group D decreased compared with that of group A (P<0.01), and compared with group B, the number of times crossing the platform of group C increased and the number of group D significantly increased (P<0.01). Decreased protein expression level of NR2B was found in group B when compared with that of group A (P<0.01), increased protein expression levels of NR2B were found in group C and group D when compared with that of group B (P<0.01), however, the expression level in group D was higher than that in group C (P<0.01). mRNA expression level of NR2B in prefrontal cortex in morphine-withdrawal rats decreased (P<0.05), however, compared with that of group B, the expression level increased in group D (P<0.05), and there was no statistical significance in increased expression level in group C (P<0.05).ConclusionAcupuncture and eletroacupunture can improve space learning and memory abilities of merphine-withdrawal rats, with better efficacy of eletroacupuncture than that of acupuncture, the mechanisms of which may be associated with the regulation of NR2B expression in prefrontal cortex.