Impact of 30-Day Oral Dosing With N-Acetyl-L-Cysteine on Sprague-Dawley Rat Physiology

A number of studies have demonstrated a protective effect associated with N-acetyl-L-cysteine (NAC) against toxic chemical exposure. However, the impact of long-term oral dosing on tssue pathology has not been determined. In this study, we assessed the impact of long-term oral NAC administration on organ histopathology and tissue glutathione (GSH) and total glutathione-S-transferase (GST) activity levels in Sprague-Dawley (SD) rats. Groups of 20 SD rats (10 male, 10 female), 8 weeks of age, were dosed daily by oral gavage with deionized H2O (negative controls) or NAC solution at a rate of 600 or 1,200 mglkgld for 30 days. Animals were euthanized 6 hours after treatment on study Day 30. There were no significant differences in final body weights or weekly average weight gain between treatment groups. Serum alanine aminotransferase (ALT) activities were significantly elevated (p less than or equal to 0.05) in NAC-treated animals compared to controls when measured on study Day 30. Histopathologic evaluation of the liver, stomach, small intestine, liver, kidneys, spleen, thymus, and lungs revealed no lesions associated with NAC administration. When measured on study Day 30, total GST acUvity for kidney and skin from NAC-treated animals were increased 39-131% as compared to controls. Tissue GSH concentrations from NAC-treated animals were increased 24-81% as compared with negative controls. Further studies are needed to determine if the observed increase in tissue GSH concentraion and GST activity provide a degree of chemoprotection against dermal and systemic chemical toxicants.