Physiological and transcriptomic analyses reveal the toxicological mechanism and risk assessment of environmentally-relevant waterborne tetracycline exposure on the gills of tilapia (Oreochromis niloticus)

Abstract

With the increasing application of tetracycline (TC) in medical treatment, animal husbandry and aquaculture in recent decades, high quantities of TC have been frequently detected in the aquatic environment, and accordingly TC-related toxicity and environmental pollution have become a global concern. The present study was performed to explore the toxicological influences of TC exposure at its environmentally relevant concentrations on the gills of tilapia Oreochromis niloticus, based on the alteration in histopathology, oxidative stress, inflammatory response, cell cycle, mitochondrial function, apoptosis, and transcriptomic analysis. Our findings revealed that TC exposure damaged the structure and function, induced oxidative stress, affected inflammatory responses, and reduced Na⁺/K⁺-ATPase (NKA) activity in the gills. TC also caused the inhibition in cell cycle, resulted in mitochondrial dysfunction and activated apoptosis. Further transcriptomic analysis indicated the extensive influences of TC exposure on the gill function, and immune system was the main target to waterborne TC exposure. These results elucidated that environmental TC had more complex toxicological effects on gills of fish than previously assessed, and provided novel insight into molecular toxicology of TC on fish and good basis for assessing the environmental risk of TC.

Keywords: Antibiotics; Environmental risk assessment; Fish; Histopathology; Metabolic disorders; Toxicological influences.