Vitamin A modulation of xenobiotic-induced hepatotoxicity in rodents.

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Abstract
Vitamin A (VA, retinol) has been shown to modulate cells of the immune system. When rats are pretreated with VA (75 mg/kg/day) for 7 days, there is greatly potentiated liver damage upon subsequent exposure to hepatotoxicants such as CCl4. This potentiated damage can be blocked by superoxide dismutase or catalase, suggesting that reactive oxygen species are playing a major role in the increased liver injury. The studies reported here examined VA-induced modulation of CCl4 hepatotoxicity in different strains of male rats, female rats, and different strains of male mice. Also, the role of VA-induced weight loss on potentiation of CCl4 injury was investigated. Rats or mice were dosed with VA (retinol) at 75 mg/kg/day, po, for 7 days. In an additional VA dose-response study, mice were given VA at 18.8, 37.5, or 75 mg/kg/day, po, for 7 days. On day 8 they were given a dose of CCl4 which elicited mild hepatic damage. On day 9 they were necropsied. Male and female Sprague-Dawley rats, and male Fischer-344 and athymic nude rats pretreated with VA had an approximately 10-fold increase in liver damage as compared to vehicle controls. Pretreatment of male Balb/C, C3H/HeJ, Swiss-Webster, or athymic nude mice resulted in a marked reduction of CCl4-induced hepatic damage. In the dose-response study in mice, increasing doses of VA elicited increasing amounts of protection from CCl4-induced liver injury. Paired feeding studies revealed that VA-induced weight loss (or decreased weight gain) had no effect on subsequent VA-induced potentiation (rats) or protection (mice) from hepatic damage caused by CCl4.(ABSTRACT TRUNCATED AT 250 WORDS)