Neurotoxicity and hepatotoxicity induced by heavy metals in freshwater fish

Heavy metal toxicity in fish

Abstract

Over recent years, aquaculture has been advancing significantly faster than other animal husbandry sectors. However, fish intake may endanger human health due to contamination with heavy metals. The levels of heavy metals are continuously increasing in freshwaters due to multiple anthropogenic activities. They bioaccumulate and affect different organs of freshwater fish. The review aims to provide data on the hepatotoxic and neurotoxic impacts of cadmium, lead, mercury, aluminum, arsenic, and chromium in freshwater fish. Neurotoxicity is mainly induced through the generation of severe oxidative stress in cells leading to abnormal neurotransmitter secretions, increased expression of apoptotic and detoxifying genes, neuroinflammation and mutations in the epigenome resulting in disrupted social and flight behavior, boosted auditory thresholds, impairing foraging ability, abnormal swimming patterns, hyperactivity, breathing problems and ultimately low mortality rate. Similarly, heavy metal- induced oxidative stress also serves as a key factor for the dysfunction of the liver. It causes lipoperoxidation, the uncontrolled activity of kinases and nuclear receptors, mitochondrial dysfunction, abnormal endocrine secretions, and activation of the intrinsic apoptotic pathway, developing necrotic regions in the liver. Ultimately, establishing histopathological lesions resulting in liver damage. For estimating environmental risk and developing pollution control strategies, the knowledge of the mechanisms of heavy metals is important.