A mechanistic investigation about hepatoxic effects of borneol using zebrafish

Histology and transcriptomic analysis reveal the inflammation and affected pathways under 2-methylisoborneol (2-MIB) exposure on grass carp

2-Methylisoborneol (2-MIB) is a common and widely distributed off-flavor compound in water. However, the toxic mechanisms of 2-MIB on aquatic organisms remain largely unexplored. In this study, grass carp larvae were exposed to different concentrations (0, 5, and 20 μg L-1) of 2-MIB for 96 h. The accumulation of 2-MIB in the dorsal muscle was measured. Histological analysis, ultrastructure observations, and transcriptomic sequencing were conducted on the liver tissues. The results showed that 2-MIB accumulated significantly in the fish muscle, with the accumulation increasing as the exposure concentration increased through gas chromatography-mass spectrometry (GC-MS) detection. Histological and ultrastructure observations indicated that 2-MIB caused concentration-dependent inflammatory infiltration and mitochondrial damage in the liver. Transcriptomic analysis revealed lipid metabolism disorders induced by exposure to 2-MIB in grass carp. Additionally, 5 μg L-1 2-MIB affected the neurodevelopment and cardiovascular system of grass carp larvae through extracellular matrix (ECM)-receptor interaction and focal adhesion pathway. Furthermore, several pathways related to the digestive system were significantly enriched, implying that 2-MIB may impact pancreatic secretion function, protein digestion and absorption processes. These findings provide new insights into the potential toxicological mechanisms of 2-MIB.

The enhanced hepatotoxicity of isobavachalcone in depigmented zebrafish due to calcium signaling dysregulation and lipid metabolism disorder

Isobavachalcone (IBC) is a flavonoid component derived from Psoraleae Fructus that can increase skin pigmentation and treat vitiligo. However, IBC has been reported to be hepatotoxic. Current studies on IBC hepatotoxicity are mostly on normal organisms but lack studies on hepatotoxicity in patients. This study established the depigmented zebrafish model by using phenylthiourea (PTU) and investigated the difference in hepatotoxicity between normal and depigmented zebrafish caused by IBC and the underlying mechanism. Morphological, histological, and ultrastructural examination and RT-qPCR verification were used to evaluate the effects of IBC on the livers of zebrafish larvae. IBC significantly decreased liver volume, altered lipid metabolism, and induced pathological and ultrastructural changes in the livers of zebrafish with depigmentation compared with normal zebrafish. The RNA-sequencing and RT-qPCR results showed that the difference in hepatotoxicity between normal and depigmented zebrafish caused by IBC was closely related to the calcium signaling pathway, lipid decomposition and metabolism, and oxidative stress. This work delved into the mechanism of the enhanced IBC-induced hepatotoxicity in depigmented zebrafish and provided a new insight into the hepatotoxicity of IBC.