Effect of Chronic Alcohol Feeding on Hepatic Iron Status and Ferritin Uptake by Rat Hepatocytes

Alcohol abuse is known to cause disturbances to iron homeostasis in man and is associated with elevated serum ferritin levels. We have previously shown that ethanol metabolism in the rat hepatocyte is associated with an immediate reduction in ferritin uptake by this cell. In this study we have examined the effect of pair-feeding the Lieber-DeCarli liquid alcohol diet on ferritin uptake by rat hepatocytes. Rat liver ferritin was radiolabeled with ⁵⁹Fe in vivo and isolated by conventional techniques. Rats were pair-fed the Lieber-DeCarli liquid alcoholic diet for 4–6 weeks. Hepatocytes, isolated from their livers by collagenase perfusion, were incubated with [⁵⁹Fe]ferritin in L-15 medium at 37°C and 4° to measure ferritin uptake and binding. The in vitro effect of ethanol on these hepatocytes was also studied. Ferritin and iron parameters were measured in the sera and hepatocytes of these animals and a comparable group of normal chowfed rats. The rate of ferritin uptake by hepatocytes from alcohol-fed rats was significantly faster than that of their pair-fed controls (0.743 ± 0.061 vs. 0.540 ± 0.042 ng/min/10⁶ cells, p < 0.05). However, the rats on Lieber-DeCarli control diet exhibited a lower hepatocyte ferritin uptake rate than chow-fed animals (79.3 ± 8.1% of the control values, p < 0.01). In vitro incubation of cells in 100 mm ethanol resulted in less inhibition of ferritin uptake by hepatocytes from alcoholic rats than from their pair-fed controls (11 ± 7.1% inhibition vs. 43.6 ± 10.7% for controls, p < 0.05). Receptor-mediated binding of ferritin to hepatocytes showed a 61% increase in saturable binding capacity for alcoholic rats (15,820 ± 4950 molecules/cell vs. 9798 ± 3622, p= 0.05). The presence of ethanol in the medium did not affect ferritin binding significantly. Although there was no significant difference in the serum iron values between all three groups, transferrin concentrations were markedly elevated in the alcohol-fed rats, resulting in a much lower transferrin iron saturation than for the control animals. Because the corresponding serum values for the diet controls were intermediate between those for the alcohol-fed rats and the chow-fed animals, these findings may reflect dietary restriction by the liquid diet, which is exacerbated by the addition of alcohol. These findings suggest that there is increased iron uptake by the hepatocyte following chronic alcohol administration, which may be due to the increased ferritin receptors. This is supported by the observation that this alcohol treatment also causes a depletion of serum ferritin. However, the decreased iron content in the alcohol-fed rats indicate that this may be due to a response to changes in iron homeostasis by the hepatocyte and/or redistribution in the body.