RESUMEN

Objective:To investigate the changes of brain energy metabolism and cognitive function in mice with specifically knocking out AMP-activated protein kinase α1 subunit ( AMPKα1) gene in the excitatory neurons by Cre-loxP recombination system. Methods:Sixteen 6-month-old mice with genotype AMPKα1 flox/flox/Camk2a-Cre/ERT2 obtained by hybrid breeding were randomly divided into AMPKα1 knockout group ( n=8) and AMPKα1 wild-type group ( n=8). Mice in the AMPKα1 knockout group were intraperitoneally injected 0.1 mL tamoxifen (20 mg/mL, dissolved in corn oil) daily for a consecutive 5 d to control AMPKα1 gene knockout in the excitatory neurons; and mice in the AMPKα1 wild-type group were intraperitoneally injected 0.1 mL corn oil daily for a consecutive 5 d. Seven d after that, Morris water maze and T maze experiments were employed to detect the spatial learning and memory abilities and spatial working memory of these mice; chemical exchange saturation transfer imaging (CEST) was used to observe the glucose metabolism in the hippocampus and cortex surrounding the hippocampus; Western blotting was used to detect the AMPKα1 and glutamate receptor 1 (GluR1) protein expressions in the hippocampus and cortex surrounding hippocampus of two groups. Results:(1) Morris water maze showed that, as compared with those in the AMPKα1 wild-type group, mice in the AMPKα1 knockout group had significantly prolonged escape latency ([13.90±3.72] s vs. [22.40±6.28] s; [11.95±3.86] s vs. [22.39±9.77] s]) on the 3 rd and 4 th d of experiment, statistically decreased times crossing the platform ([5.25±1.83] times vs. [1.75±1.28] times, P<0.05). (2) T-maze experiment showed that as compared with that of the AMPKα1 wild-type group, the free alternation rate in mice of the AMPKα1 knockout group was significantly decreased ([73.21±9.16]% vs. [48.21±11.29]%, P<0.05). (3) CEST showed that the glucose metabolism levels in the hippocampus and cortex surrounding the hippocampus of AMPKα1 knockout group were significantly lower than those in AMPKα1 wild-type group (1.51±0.81 vs. 2.77±0.67; 1.31±0.83 vs. 2.42±0.95, P<0.05). (4) Western blotting showed that the AMPKα1 and GluR1 protein expressions in the hippocampus and cortex surrounding the hippocampus of the AMPKα1 wild-type group were significantly higher than those of the AMPKα1 knockout group (AMPKα1: 0.70±0.05 vs. 0.49±0.03, 0.98±0.04 vs. 0.64±0.06; GluR1: 1.22±0.18 vs. 0.60±0.11, 0.96±0.08 vs. 0.79±0.04, P<0.05). Conclusion:Specifically knocking out AMPKα1 in excitatory neurons can result in abnormal glucose metabolism in the brain of mice, and thus cause cognitive dysfunction, whose mechanism may be related to excitatory synaptic disorder caused by energy metabolism disorder.