Syringic acid modulates methyl cellosolve-induced hepatic upregulation of the PI3K-Akt-mTOR pathway and inhibition of p53-Bax-caspase-3-dependent apoptosis in rats

Abstract

BackgroundMethyl cellosolve (METC) is a widely used industrial solvent due to its amphipathic nature. It is found in household materials such as liquid soaps, dyes, inks, brake fluids, herbicides, etc. This makes exposure in humans incessant and indiscriminate. The PI3K-Akt-mTOR and the intrinsic apoptotic pathways are very important cellular activities. While the former participates in cell growth, proliferation, and survival, the latter coordinates the death of abnormally functional cells, thereby stopping their proliferation. Given that background, we studied the hepatoprotective effect of syringic acid (SA) on METC-induced hepatotoxicity by checking the involvement of the PI3K-Akt-mTOR and apoptotic pathways in male Wistar rats. MethodsThirty (30) rats divided into six groups were used. Rats in group 1 served as control, those in group 2 were administered METC for 30 consecutive days, and those in groups 3, 4, and 5 were treated with 25, 50, and 75 mg/kg body weight of SA respectively also for 30 consecutive days immediately after each day METC administrations, while rats in group 6 received 75 mg/kg body weight of SA only throughout. ResultsFollowing analyses, METC-induced activation of the PI3K-Akt pathway and inhibition of apoptosis were marked by a significant elevation in the liver gene expressions of PI3K, Akt, mTOR, PTEN, FoxO1, and TSC2 as well as a significant downregulation in the protein expressions of p53, caspase 3, Bax, and a significant upregulation in Bcl2 protein expression compared with control rats. SA treatment (25 mg/kg only) significantly downregulated the hepatic mTOR, FoxO1, and TSC2 gene expressions, while in addition to mTOR, FoxO1, and TSC2 genes, treatments with 50 and 75 mg/kg significantly downregulated the liver gene expressions of PI3K, Akt, and PTEN compared with METC only exposed rats. For protein expression, all the doses of SA treatment significantly downregulated the liver Bcl2 level (an antiapoptotic protein), while 75 mg/kg of SA only significantly upregulated the liver p53, Bax, and caspase 3 protein expressions (thereby ensuring the apoptosis of damaged cells) compared with METC-only exposed rats. ConclusionsIn conclusion, METC-induced liver activation of PI3K-Akt-mTOR signaling and inhibition of intrinsic apoptotic pathway was recorded, suggesting that one mechanism of METC toxicity may be through the advancement of cell survival and growth as well as inhibition of apoptosis. SA treatment (most especially by 75 mg/kg) modulated these two biochemical processes through the inhibition of participatory players in the rats.