Hexavalent Chromium Induces Defense Responses, Hepatocellular Apoptosis, and Lipid Metabolism Alterations in New Zealand Rabbit Livers.

Abstract

<b>Background</b>: Hexavalent chromium (Cr(VI)) can migrate into soil and water, posing risks to animal health. However, it remains unclear whether Cr(VI) perturbs essential trace elements and antioxidant gene expression, triggers apoptosis, or disrupts hepatic lipid metabolism in New Zealand rabbits. <b>Methods</b>: To address this knowledge gap, twenty-four 30-day-old New Zealand rabbits were randomly allocated to one control and three Cr(VI)-treated groups (differing in Cr(VI) concentration) and maintained for 28 days. Livers were then harvested for analysis. Total Cr and essential trace elements were quantified by ICP-OES. Hematoxylin-eosin staining and transmission electron microscopy were employed to assess histopathological and ultrastructural alterations, respectively. Hepatic lipid accumulation was visualized with Oil Red O staining. QRT-PCR was used to determine the expression of antioxidant and lipid-metabolism-related genes. <b>Results</b>: Cr(VI) was detectable in liver tissue at all exposure levels and was accompanied by significant decreases in four essential trace elements (Fe, Mn, Zn, and Se); Cu displayed a biphasic response, rising at lower Cr(VI) doses before declining at higher doses. Histopathological and ultrastructural analyses revealed overt hepatic injury. Notably, all Cr(VI) treatments elevated antioxidant gene expression, indicating activation of hepatic defense pathways. Lipid metabolism was also disrupted, evidenced by increased lipid deposition and up-regulation of genes governing hepatic fat metabolism. <b>Conclusions</b>: Collectively, these findings demonstrate that Cr(VI) elicits dose-dependent activation of hepatic antioxidant defenses, promotes apoptosis, and induces lipid-metabolic disorders in New Zealand rabbit hepatocytes. This study provides novel mechanistic insights into Cr(VI)-induced hepatotoxicity and offers a valuable reference for evaluating the hepatic risks of environmental Cr(VI) exposure in this species.