Lead and Cadmium Co-exposure Mediated Toxic Insults on Hepatic Steroid Metabolism and Antioxidant System of Adult Male Rats

Abstract

The redox status and steroid metabolism of liver of adult male rat exposed to lead (Pb) and cadmium (Cd) either alone or in co-exposure (0.025 mg/kg body weight intraperitoneally/15 days) was studied. Pb and Cd significantly accumulated in the liver. The activity of steroid metabolizing enzymes 17-betahydroxysteroid oxidoreductase and uridine diphosphate-glucuronyltransferase were decreased in experimental animals. 17-beta-Hydroxysteroid dehydrogenase was reduced to 33%, 38%, and 24% on treatment of Pb, Cd, and co-exposure (Pb + Cd). Furthermore, the activity of uridine diphosphate-glucuronosyltransferase was significantly reduced to 27% (Pb exposure), 36% (Cd exposure), and 25% (co-exposure of Pb + Cd). Cd exposure exhibited more toxic effect than Pb, while co-exposure demonstrated the least. The activities of antioxidant enzymes, superoxide dismutase, catalase, glutathione reductase, and glucose-6-phosphate dehydrogenase decreased and glutathione peroxidase increased in mitochondrial and post-mitochondrial fractions. The level of lipid peroxidation increased, and cellular glutathione concentration decreased. Hepatic DNA was decreased, whereas RNA content and the activity of alanine transaminase remained unchanged. Histological studies revealed that only Cd-exposed groups exhibited cytotoxic effect. These results suggest that when Pb and Cd are present together in similar concentrations, they exhibited relatively decreased toxic effect when compared to lead and cadmium in isolation with regard to decreased steroid metabolizing and antioxidant enzyme activities. This seems that the toxic effect of these metals is antagonized by co-exposure due to possible competition amongst Pb and Cd for hepatic accumulation.

Antioxidant response and metal accumulation in tissues of Iberian green frogs (Pelophylax perezi) inhabiting a deactivated uranium mine

“…Pandya et al (2010) also obtained similar results in liver of male rats co-exposed to Pb and Cd. Some metals like Al tend to be more concentrated in the lung as age increases (Schaller et al 1994b) and others, like Be tend to enter via respiratory tract (Rossman 1994).…”

Biochemical and molecular effects of gestational and lactational coexposure to lead and cadmium on ovarian steroidogenesis are associated with oxidative stress in f1 generation rats

“…Both in vivo and in vitro studies have suggested generation of reactive oxygen species (ROS) and alteration of antioxidant system in animals as one of the mechanisms for the toxic effects of lead and cadmium [47][48][49][50][51]. Our results show that ovarian GSH content is decreased in all the metal-treated groups.…”

Joint Toxicity of Different Heavy Metal Mixtures after a Short-Term Oral Repeated-Administration in Rats

“…Experimental and epidemiological evidence indicates that combination effects generated by multi-heavy metals might be quite different from that induced by the same individual metal, because heavy metals at individual low acting concentrations can elicit higher toxicity on interactions with other environmental toxicants [ 11 , 12 , 13 , 14 ]. Goyer [ 15 ] has shown toxic metals have significant interactions with essential metals (iron, manganese, calcium) which can influence the essential metal status in the human body.…”

“…Pandya et al . [ 14 ] showed that under similar dosages, when Pb and Cd are present together, the toxic effect is antagonized by co-exposure due to possible competition among Pb and Cd for hepatic accumulation. Damian et al .…”