Neurochemical changes in the hippocampus and prefrontal cortex associated with electroacupuncture for learning and memory impairment

Electroacupuncture (EA) has been widely used to treat cognitive impairment following cerebral ischemia. However, the functional mechanisms of EA have not been fully elucidated. The aim of the present study was to investigate whether EA at the GV 20 and DU 24 acupoints can improve the learning and memory ability via alteration of the neurochemical metabolism in the hippocampus (HPC) and prefrontal cortex (PFC) of rats with ischemia and reperfusion (I/R) injury. Sprague-Dawley male rats were randomly divided into three groups, namely the sham group (n=12), the middle cerebral artery occlusion (MCAO) group (n=12) and the EA treatment (MCAO + EA) group (n=12). MCAO was performed to establish the left focal cerebral I/R injury model, and the GV 20 and DU 24 acupoints were then stimulated with EA for 30 min per time, once daily, for 7 consecutive days. The Morris water maze (MWM) test was used to assess learning and memory ability. T2-weighted imaging was used to assess the cerebral infarct volume. Magnetic resonance spectroscopy was used to assess neurochemical metabolism of HPC and PFC. The neurological scores of the MCAO + EA group were significantly reduced compared with those of the MCAO group 7 days after EA treatment (P<0.01). The escape latency of the MWM test in the MCAO + EA group was found to be shorter compared with that in the MCAO group (P<0.01). The number of rats crossing through the platform area was significantly higher in the MCAO + EA group compared with that in the MCAO group (P<0.01). The cerebral infarct volume was also decreased in the MCAO + EA group compared with the MCAO group (P<0.05). The ratios of N-acetylaspartate (NAA)/creatine (Cr) and choline (Cho)/Cr of left-to-right HPC were increased in the MCAO + EA group compared with the MCAO group; however, the ratio of glutamate (Glu)/Cr did not change significantly (P>0.05). The ratios of NAA/Cr, Cho/Cr and Glu/Cr of left-to-right PFC were elevated (P<0.05). In conclusion, EA at the GV 20 and DU 24 acupoints may ameliorate learning and memory ability, possibly through increasing the levels of NAA and Cho in the HPC and PFC of rats with I/R injury.