Objective To explore the effect of ligustrazine on the learning and memory function of rats with aluminum-induced cognitive impairment and its mechanism.Methods Sixty male Wistar rats were divided into a blank control group,a model group,a low-dose ligustrazine group,a high-dose ligustrazine group,and a piracetam group using a random number table method,with 12 rats in each group.The rats in the blank control group were not subjected to any treatment;the rats in the model group,low-dose ligustrazine group,high-dose ligustrazine group,and piracetam group were first prepared with aluminum toxicity models by daily gavage of 100 mg·kg-1 AlCl3 solution.After successful modeling,the rats in the piracetam group were intragastrically administered with piracetam at a dose of 400 mg·kg-1,while rats in the low-dose and high-dose ligustrazine groups were intragastrically administered with 100 and 200 mg·kg-1 ligustrazine,respectively;the rats in the blank control group and the model group were intragastrically administered with the same volume of physiological saline.All rats in the five groups received intragas tric administration once a day for 30 consecutive days.After 30 days of intervention,the Morris water maze test was used to evaluate the learning and memory function of rats in the five groups.After completing the water maze experiment,rats in the five groups were anesthetized with 200 g·L-1 chloral hydrate,and their brain tissues were quickly removed after decapitation.Immunohistochemical staining was used to observe the expression of calcium voltage-gated channel subunit alpha 1E(CACNA1E),calmodulin(CALM),and brain-derived neurotrophic factor(BDNF)in the hippocampal CA1 region of rats in the five groups;Western blot was used to detect the relative expression levels of CACNA1E,CALM,and BDNF proteins in the hippocampal CA1 region of rats in the five groups;and real-time fluorescence quantitative polymerase chain reaction was used to detect the relative expression levels of CACNA1E,CALM,and BDNF mRNA in the hippocampal CA1 region of rats in the five groups.Results On the 1st day of the Morris water maze test,the latent periods of rats in the model group,piracetam group,low-dose ligustrazine group,and high-dose ligustrazine group were significantly higher than those in the blank control group(P＜0.05);there was no statistically significant difference in the latent periods of rats among the piracetam group,low-dose ligustrazine group,high-dose ligustrazine group,and model group(P＞0.05).On the 3rd day of the Morris water maze test,the latent periods of rats in the model group,piracetam group,low-dose ligustrazine group,and high-dose ligustrazine group were significantly higher than those in the blank control group(P＜0.05);the latent periods of rats in the piracetam group and high-dose ligustrazine group were significantly lower than those in the model group and low-dose ligustrazine group(P＜0.05);there was no statistically significant difference in the latent periods of rats between the low-dose ligustrazine group and the model group(P＞0.05).On the 5th day of the Morris water maze test,the latent periods of rats in the model group,piracetam group,low-dose ligustrazine group,and high-dose ligustrazine group were significantly higher than those in the blank control group(P＜0.05);the latent periods of rats in the piracetam group and high-dose ligustrazine group were significantly lower than those in the model group and low-dose ligustrazine group(P＜0.05);there was no statistically significant difference in the latent periods of rats between the low-dose ligustrazine group and the model group(P＞0.05).On the 3rd and 5th days of the Morris water maze test,there was no statistically significant difference in the latent periods of rats between the piracetam group and the high-dose ligustrazine group(P＞0.05).The times of rats crossing platform in the model group,piracetam group,low-dose ligustrazine group,and high-dose ligustrazine group were significantly lower than those in the blank control group,and the times of rats crossing platform in the piracetam group and high-dose ligustrazine group were significantly higher than those in the model group and low-dose ligustrazine group(P＜0.05);there was no statistically significant difference in the times of rats crossing platform between the low-dose ligustrazine group and the model group(P＞0.05);there was no statistically significant difference in the times of rats crossing platform between the piracetam group and the high-dose ligustrazine group(P＞0.05).Under the microscope,brown CACNA1E,CALM,and BDNF positive cells could be observed in the hippocampal CA1 region.The expressions of CACNA1E,CALM,and BDNF proteins in the hippocampal CA1 region of rats in the model group,piracetam group,low-dose ligustrazine group,and high-dose ligustrazine group were significantly lower than those in the blank control group,and the expressions of CACNA1E,CALM,and BDNF proteins in the hippocampal CAl region of rats in the piracetam group and high-dose ligustrazine group were significantly higher than those in the model group and low-dose ligustrazine group(P＜0.05);there was no statistically significant difference in the expressions of CACNA1E,CALM,and BDNF proteins in the hippocampal CAI region of rats between the low-dose ligustrazine group and the model group(P＞0.05);there was no statistically significant difference in the expressions of CACNA1E,CALM,and BDNF proteins in the hippocampal CA1 region of rats between the piracetam group and the high-dose ligustrazine group(P＞0.05).The relative expression levels of CACNA1E,CALM,and BDNF proteins and mRNAs in the hippocampal CA1 region of rats in the model group,piracetam group,low-dose ligustrazine group,and high-dose ligustrazine group were significantly lower than those in the blank control group(P＜0.05);the relative expression levels of CACNA1E,CALM,and BDNF proteins and mRNAs in the hippocampal CA1 region of rats in the piracetam group and high-dose ligustrazine group were significantly higher than those in the model group and low-dose ligustrazine group(P＜0.05);there was no statistically significant difference in the relative expression levels of CACNA1E,CALM,and BDNF proteins and mRNAs in the hippocampal CA1 region of rats between the low-dose ligustrazine group and the model group(P＞0.05);there was no statistically significant difference in the relative expression levels of CACNA1E,CALM,and BDNF proteins and mRNAs in the hippocampal CA1 region of rats between the piracetam group and the high-dose ligustrazine group(P＞0.05).Conclusion Ligustrazine has significant protective effects on aluminum-induced cognitive impairment in rats and can greatly enhance the learning and memory function of rats.The mechanism may be related to the up-regulation of CANA1E,CALM and BDNF expression in the brain induced by ligustrazine.