| Abstract: | Vitamin D-depleted and vitamin D-replete rats were treated with allyl alcohol (AA) or bromobenzene (BB). The severity of the hepatotoxicity was evaluated by the serum concentrations of aspartate aminotransferase, alanine aminotransferase and sorbitol dehydrogenase, the histomorphological appearance of the lesions, and the amount of cytochrome P-450 destroyed. The activity of the monooxygenases was also evaluated. All parameters indicated that vitamin D depletion alone did not lead to any signs of liver toxicity nor did it modify the pattern of toxicity of either AA or BB. However, the intensity of the response in the periportal (AA treatment) and in the centrilobular (BB treatment) zones was modified by the depletion. Vitamin D depletion was accompanied by increased hepatic damage due to AA while BB resulted in less hepatic damage in vitamin D-depleted compared to vitamin D-replete animals. The metabolic profile of the liver mixed function oxidases indicated that its intraacinar distribution was modified by the depletion. Although the overall activity toward the substrates studied was not changed by vitamin D depletion, two out of the three enzyme activities studied suggested that vitamin D-depleted rats were poorer "centrilobular metabolizers" and better "periportal metabolizers" than vitamin D-replete rats. These observations correspond to increased periportal and decreased centrilobular toxicity in vitamin D-depleted animals. These results suggest that vitamin D depletion associated with severe hypocalcemia may be associated with an intraacinar modulation of enzyme systems as well as with an intraacinar difference in the susceptibility of the liver to certain chemicals. |
