Dietary aflatoxin B1 exposure induced the inflammation and apoptosis in freshwater fish (Channa argus) via disturbing ROS/ERS signaling axis

Abstract

This study examined the impact of aflatoxin B₁ (AFB₁) on inflammation and apoptosis within the intestine and head kidney of freshwater fish - northern snakehead (Channa argus), focusing on the interaction between oxidative stress and endoplasmic reticulum stress (ERS) within the signaling pathways. In this study, 600 snakeheads, each weighing approximately 7.52 ± 0.02 g, were categorized into five groups, each consisting of three replicates. These groups were administered diets with incremental concentrations of AFB₁ (0 (CON), 50 (AF1), 100 (AF2), 200 (AF3), and 400 ppb (AF4)) over a duration of eight weeks. Histopathological analysis of the intestine and head kidney showed different degrees of pathological changes in the AFB₁-added groups. Exposure to AFB₁ markedly elevated ROS levels and activities of enzymes like MDA and 8-OHdG, concurrently decreasing the activities of CAT, GST, SOD, GSH, GPX, and GR within both organs. Additionally, as AFB₁ levels increased, a decrease in the expression of genes associated with antioxidant functions (gst, cat, sod, gsh-px, nqo-1, ho-1, and nrf2) was observed. Analysis via quantitative real-time PCR (qRT-PCR) revealed changes in the mRNA levels of genes related to ERS (grp78, ire1, jnk, perk, chop, and xbp1), apoptosis (cas-3, cas-9, bax, bcl-2, cyt-c, and cas-8), and inflammation (nf-κb, tnf-α, iκbα, il-1β, il-8, and il-6) in both the intestine and head kidney, we found that AFB1 induces overproduction of ROS and exacerbates ERS, thereby activating apoptosis and inflammation. The results underscore the interconnected roles of oxidative stress, ERS, apoptosis, and inflammation in the damage observed in the fish's intestine and head kidney following AFB₁ exposure, indicating that the ROS-ERS signaling axis may play a significant role in the induced inflammation and apoptosis. This study offers valuable insights for further exploration into the effects of AFB₁ and its operational mechanisms in the head kidney and intestine of fish.