Interrelationships between vitamin D3 and 25-hydroxyvitamin D3 during chronic ethanol administration in the rat.

Vitamin D [D] depleted female Sprague-Dawley rats were fed for a period of 4 wk a D deficient diet containing 36% of total calories as ethanol while control animals received an isocaloric regimen where ethanol was substituted for by dextrins. In conjunction with the ethanol feeding 92 I.U. of [14C]-vitamin D3 [(14C)-D3] were administered by intragastric gavage 3 times 1 wk for 3 2/3 wk. At the end of the experiment, [14C]-D3 and [14C]-25-hydroxyvitamin D3 [(14C)-25(OH)D3] concentrations were analyzed in plasma, liver, striated muscle and adipose tissue. Body reserves in unchanged [14C]-D3 were significantly reduced by ethanol treatment as seen by 24%, 26%, and 59% lower plasma (p less than 0.02), muscle (p less than 0.001) and adipose tissue (p less than 0.001) [14C]-D3 concentrations in ethanol-treated compared to control rats. In contrast total plasma and liver [14C]-25(OH)D3 content were increased by 30% (p less than 0.05) and 55% (p less than 0.001) respectively. This increased liver and plasma [14C]-25(OH)D3 following ethanol treatment was not accompanied by a proportional [14C]-25(OH)D3 incorporation into muscle and adipose tissue. These results suggest that during steady state conditions 25(OH)D3 production is increased during chronic ethanol administration while the body pool in unchanged D3 is significantly lowered. These results also point out that in the rat plasma 25(OH)D concentrations are not a reliable guide for the determination of vitamin D status during chronic ethanol administration.