Background
Noise can cause not only auditory system injury, but also liver damage. However, the biomarkers and pathological mechanism of noise-induced liver injury are not clear yet.
Objective
To observe the effect of noise on the morphological structure and functions of rat liver.
Methods
A total of 30 Wistar rats were randomly divided into a normal control group, a low noise exposure group (95 dB sound pressure level (SPL), and a high noise exposure group (105 dB SPL). After 30 days of noise exposure, blood was collected, and livers were harvested and fixed. The pathological changes of livers were observed. The levels of biochemical indicators of liver function, blood glucose, and blood lipid were measured. Serum metabolites were detected by ultra-high-pressure liquid chromatography-tandem quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS). Differential metabolite markers and metabolic pathways were identified.
Results
Compared with the control group, the body weight gain decreased in the low noise group and the high noise group after noise exposure (P<0.001,P<0.05). The pathological results showed that noise caused the rat livers’ morphological and structural damage at various degrees, and damage of the high noise exposure group was more serious. Compared with the control group, the serum levels of aspartate aminotransferase, albumin, and glycosylated serum protein in the low noise exposure group were increased (P<0.05), but the total bile acid level was decreased (P<0.05). The serum levels of alanine aminotransferase, aspartate aminotransferase, albumin, triglyceride, low density lipoprotein, and glycosylated serum protein in the high noise group exposure were increased (P<0.05), but the glucose level was decreased (P<0.05). In the serum metabolomics analysis, 11 differential metabolites were screened out in the low noise exposure group, which were mainly enriched in 3 pathways (thiamine metabolism, primary bile acid biosynthesis, and bile secretion) related to liver metabolism. Four differential metabolites were screened out in the high exposure noise group, which were mainly enriched in four significantly different metabolic pathways (insulin signaling pathway, non-alcoholic fatty liver disease, bile secretion, and insulin secretion). All the metabolic pathways involved in bile acid secretion and metabolism.
Conclusion
Nosie exposure can not only damage the liver structure of rats, but also affects the metabolism functions of liver. The mechanism may be related to bile acid secretion metabolic pathway.
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