Studies on toxicity due to exposure of low dose of organic mercury in rattus norvegicus

Abstract

Many studies have reported toxic and carcinogenic effects induced when humans and animals are exposed to certain metals. However, their rich coordination chemistry and redox properties are such that they are capable of escaping out of the control mechanisms such as homeostasis, transport, compartmentalization and binding to the designated tissue and cell constituents. A growing amount of results provide evidence that toxic and carcinogenic metals are capable of interacting with nuclear proteins and DNA causing oxidative deterioration of biological macromolecules. Detailed studies in the past two decades have shown that metals like iron, copper, cadmium, chromium, mercury, nickel, vanadium possess the ability to produce reactive radicals resulting in DNA damage, lipid peroxidation, depletion of protein sulfhydryls and other effects. Mercury is the only metal which is liquid at room temperature. It exists in nature mainly as three different molecular species; elemental (Hg), inorganic (e.g., Hg+, Hg2+) and organic e.g., methylmercury (MeHg), ethylmercury and phenylmercuric acetate. The elemental mercury (Hg) and its compounds have no known normal metabolic function. Their presence in the cells of living organisms represents contamination from natural and anthropogenic sources; all such contamination must be regarded as undesirable and potentially hazardous. Methylmercury is formed by biotic and abiotic methylation of mercury. It has been used as a fungicide, disinfectant, and in industrial processes. It is highly toxic and readily absorbed by the body following ingestion and inhalation. It may be metabolized to inorganic mercury by the liver and kidneys, with further transformation occurring to form the divalent cation. It is excreted as inorganic mercury, primarily in the feces. It is neurotoxic to several species of experimental animal and to humans. The main source of methylmercury to the general population is through the consumption of contaminated fish and other food products.