Embryotoxicity and upregulation of Hsp70 Gene Expression in zebrafish (Danio rerio) embryos exposed to e-cigarette fluid

Abstract

Although e-cigarettes have been marketed as the safer alternative to tobacco cigar smoking, most researchers are still skeptical as the implications of their usage have not yet been thoroughly investigated. In line with this, this study aims to determine the chemical components in three (3) different flavors of e-cigarette fluid (i.e. strawberry, vanilla, and tobacco) and whether exposure to varying dilutions of these treatments induce abnormalities and hsp70 gene expression in zebrafish embryos. The chemical components of the e-cigarette fluid were determined via gas chromatography-mass spectrometry, and the treated embryos were subjected to ZFET, and then hsp70 gene expression analysis by RT-qPCR. All treatments were significantly embryotoxic for the parameters of lethality, heart rate, hatching, and malformation occurrence. Similarly, all treatments induced the upregulation of hsp70 gene expression. The embryos exposed to the vanilla and tobacco-flavored e-cigarette fluid exhibited similar trends in their results, which coincided with their similarity in chemical composition. Meanwhile, the embryos exposed to the strawberry-flavored e-cigarette fluid exhibited the most pronounced effects, distinct from those of the other two (2) flavors, which may be attributed to its possession of the highest relative nicotine content among all three (3) flavors.