Investigation on the mechanism of hepatotoxicity of dictamnine on juvenile zebrafish by integrating metabolomics and transcriptomics.

Dictamnine(DIC), as the key pharmacological component of the classical Chinese herbal medicine cortex dictamni, possesses multiple pharmacological activities such as anti-microbial, anti-allergic, anti-cancer, and anti-inflammatory activities, however it is also the main toxicant of cortex dictamni induced hepatic damage, yet the underlying molecular mechanisms causing hepatic damage are still largely unknown. With the purpose of explore possibilities hepatotoxicity of dictamnine in zebrafish and to identify the key regulators and metabolites involved in the biological process, we administered zebrafish to dictamnine at a sub-lethal dose (<LC10) for 24 h and performed biochemical index tests, pathological observations, metabolomics, and transcriptomics analyses. The results showed that the liver function indexes such as ALT and AST were affected after the exposure treatment with dictamnine, and the hepatic damage, lipid droplet formation, and increased apoptosis were observed in zebrafish by HE, oil red O(ORO), and Acridine orange hydrochloride(AO)staining. Transcriptome sequencing analysis showed that dictamnine exposure could generate 5696 down-regulated and 4936 up-regulated DEGs(Differential Expressed Genes); metabolomics analysis showed that 36 potential biomarkers were disturbed by dictamnine exposure treatment in juvenile zebrafish. Integration of metabolomics data and transcriptomics data showed that Patatin like phospholipase domain containing 3 Gene Patatin Like Phospholipase Domain Containing 3(PNPLA3), Lactase Gene(LCT), and Galactosidase Beta 1(GLB1) genes were involved in the regulation of 12 key potential biomarkers related to Galactose metabolism and Glycerophospholipid metabolism, such as LysoPC(16:0/0:0) and UDP-4-dehydro-6-deoxy-D-glucose, which in turn regulated pathways of Galactose metabolism and Glycerophospholipid metabolism and consequently induced hepatotoxicity. The comprehensive evaluation of the hepatotoxicity induced by dictamnine was realized from multiple levels, perspectives and indexes by the integrated evaluation method of zebrafish modeling, which supported the applicability of zebrafish in the evaluation of hepatotoxicity of traditional Chinese medicine, and supplied the scientific basis for elucidating the molecular mechanism of the hepatotoxicity induced by dictamnine, as well as guided the development of the toxicity-reducing therapies by dictamnine in the future.