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Objective: To investigate the metabolic changes in rats with minimal hepatic encephalopathy (MHE) treated with oral magnesium sulphate administration. Materials and Methods: A total of 30 Sprague-Dawley rats were divided into a control group and MHE group (further divided into an MHE group and an MHE-Mg group treated with oral administration of 124 mg/kg/day magnesium sulphate). Morris water maze (MWM), Y maze and narrow beam walking (NBW) were used to evaluate cognitive and motor functions. Brain manganese and magnesium content were measured. The metabolic changes in rats with MHE were investigated using hydrogen-nuclear magnetic resonance. Metabolomic signatures were identified with enrichment and pathway analysis. Results: A significantly decreased number of entries into the MWM within the range of interest, longer latency and total time during NBW, and higher brain manganese content were found in rats with MHE. After magnesium sulphate treatment, the rats with MHE had better behavioural performance and lower brain manganese content. The 25 and 26 metabolomic signatures were identified in the cortex and striatum of rats with MHE. The pathway analysis revealed alanine, aspartate and glutamate metabolism as the major abnormal metabolic pathways associated with these metabolomic signatures. Conclusion: Alanine, aspartate and glutamate metabolism are major abnormal metabolic pathways in rats with MHE, which could be restored by magnesium sulphate treatment.