Effect and mechanism of DL-3-n-butylphthalide on emotional memory in mice with chronic alcoholism

Objective To investigate the improvement and possible mechanism of dl-3-n-butylphthalide (NBP) on the emotional memory of chronic alcoholism model mice. Methods Twenty-four adult male C57/BL6 mice were randomly divided into control group (CON, n=8), model group (AT, n=8), treatment group (AT+ NBP, n=8). Mice in AT group and AT+ NBP group were administrated with alcohol to establish chronic alcoholism model. In the AT+ NBP group, the mice was administrated with NBP (40 mg/kg) by gavage once a day for 14 days during the alcohol modeling period. Ang the mice in AT group and CON group was given the same dose of corn oil by gavage.Open field test was used to evaluate anxiety-like behavior, tail suspension test to evaluate depression-like behavior, Morris water maze and new object recognition to evaluate memory ability, and TUNEL staining to evaluate the number of neuron apoptosis. The primary cultured neurons were interfered by alcohol and NBP at the cell level, and the calcium concentration in the neurons was detected by fluorescence calcium imaging. Descriptive analysis, t-test and one-way ANOVA were processed by SPSS 17.0. Results The results of open field test showed that the exploration time of AT+ NBP group was longer than that of AT group ((50.68±7.82)s, (38.50±13.93)s; t=-2.16, P<0.05)). In the spatial memory test, the target quadrant exploration time of AT+ NBP group was longer than that of AT group ((28.02±7.13)s, (20.98±5.58)s; t=-2.20, P<0.05). In short memory test, the cognitive coefficient RI (0.83±0.08) of AT+ NBP group was higher than that of AT group (0.68±0.10) (t=-3.13, P<0.05). Compared with CON group, the number of neuron apoptosis in prefrontal cortex in AT group increased ((17.33±2.51), (115.67±6.50); t=-24.41, P<0.001), and that in AT+ NBP group decreased compared with AT group((45.00±5.57)) (t=14.29, P<0.001). The number of apoptosis neurons in the dentate gyrus of the hippocampus in AT group (13.75±4.79) was also less than that in the AT+ NBP group (5.75±3.30) (t=2.75, P<0.05). Calcium concentration in nerve cells was detected that the three concentrations of alcohol (100 mmol/L, 200 mmol/L and 300 mmol/L) led to a significant increase in the RFU within the nerve cells (△F/F) ((1.43±0.32), (2.31±1.39), (1.21±0.73); t=-7.67, -2.85, -2.86, all P<0.05). In comparison, the changes of RFU in the three groups treated with NBP treatment were relatively stable ((0.04±0.01), (-0.03±0.01), (-0.04±0.02); t=7.96, 2.96, 2.92, all P< 0.05). Conclusion The 3-n-Butylphthalide can improve the learning and memory ability of chronic alcoholism model mice, which may be related with the inhibition of neuron apoptosis and the influence of intracellular calcium homeostasis. Key words: DL-3-n-Butylphthalide; Alcoholism; Anxiety; Memory; Neuronal apoptosis; Calcium homeostasis