Accuracy and precision of 31P-MRS assessment for evaluating the effect of melatonin-pretreated mitochondria transferring on liver fibrosis of rats

This study examined the reliability of 31phosphorus-magnetic resonance spectroscopy (31P-MRS) to measure parameters of liver metabolic function in the intact animals. These parameters can help us to evaluate the severity and prognosis of liver fibrosis. In addition, 31P-MRS was also used to examine the protective effects of melatonin on liver mitochondria. An animal model of liver fibrosis was established via intraperitoneal administration of thioacetamide (TAA) to rats. Rats were scanned at baseline, week 3 and 6 after TAA treatment, respectively, to measure the longitudinal changes of phosphorus metabolite levels by 31P-MRS at 9.4 T. The results showed a consistent decline in the levels of phosphorus metabolites (inorganic phosphate, α-ATP, γ-ATP and NADH) in rats with fibrosis. Impaired mitochondrial respiration capacity, collagen accumulation and the extent of fibrosis in liver were markedly associated with decreased concentrations of phosphorus metabolites. Melatonin-pretreated mitochondria transferring efficiently prevented TAA-induced liver damage mainly by restoring mitochondrial function. In conclusion, the levels of phosphorus metabolites could serve as the indicators of mitochondrial oxidative capacity and thus provides a novel tool to evaluate mitochondrial integrity in the in vivo condition by using 31P-MRS in the setting of liver fibrosis.