1. Lipid peroxidation and hepatic fibrogenesis were investigated in 25 carbon tetrachloride-treated rats and in 25 control animals. Rats were further divided into two groups to receive either a standard diet or one supplemented with zinc. From each group, animals were killed at weeks 3 and 18 of the experiment for histological and biochemical assessments which included hepatic lipid peroxide and collagen concentrations and plasma zinc concentration as well as the hepatic activities of proline hydroxylase and collagenase. 2. Results indicated that oral zinc supplementation was associated with a decrease in lipid peroxidation (mean 51%; P < 0.05), collagen deposition (mean 32%; P < 0.001) and proline hydroxylase activity (mean 30%; P < 0.05) at week 18, together with an increase in collagenase activity (mean 208%; P < 0.01) at week 3, in carbon tetrachloride-treated rats. 3. There was a significant direct correlation between lipid peroxidation and proline hydroxylase activity in carbon tetrachloride-treated rats (r = 0.52; P < 0.01) and also a significant inverse correlation between lipid peroxidation and plasma zinc concentration in these animals (r = -0.62; P < 0.001). 4. These findings are consistent with the hypothesis that hepatic lipid peroxidation plays an important role in the aetiology of hepatic fibrogenesis and that zinc mitigates the process.

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The effects of dietary zinc on hepatic collagen and prolyl hydroxylase activity in normal and alcoholic rats has been investigated in four groups of pair-fed male Wistar rats given either liquid ethanol or a control diet for 12 wk. Each group of pair-fed animals received a diet with a different zinc concentration (standard diet, 7.6 mg/L; low-zinc diet, 3.4 mg/L; zinc-supplemented diet, 76 mg/L; and zinc-extrasupplemented, 300 mg/L. There were no significant differences in hepatic collagen concentration and prolyl hydroxylase activity between alcoholic and normal rats receiving a standard diet (collagen, 77 +/- 5 and 73 +/- 6 micrograms/mg protein; and prolyl hydroxylase; 37 +/- 26 and 36 +/- 22 cpm/mg protein). Alcoholic rats fed a low-zinc diet showed increased prolyl hydroxylase activity (75 +/- 10 cpm/mg protein, p less than 0.05), although no changes in hepatic collagen (77 +/- 10 micrograms/mg protein) were observed in comparison with rats fed a standard alcoholic diet. By contrast, hepatic collagen was significantly lower in alcoholic rats fed a zinc-supplemented diet (66 +/- 4 and 63 +/- 3 micrograms/mg protein, p less than 0.05 and p less than 0.01, respectively), and hepatic prolyl hydroxylase activity was particularly lower in rats receiving zinc 300 mg/L (18 +/- 20 cpm/mg protein). Similar effects were observed in normal rats. We conclude that dietary zinc influences hepatic prolyl hydroxylase activity and collagen deposition in alcoholic rats, and in consequence, the control of dietary zinc is necessary to assess the effects of alcohol on collagen metabolism in rats.

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