The effects of
vitamin A nutritional status on the levels of expression of
retinoic acid nuclear receptors (RAR), and the
retinoic acid-responsive gene,
tissue transglutaminase, were determined in rats. Weanling male Sprague-Dawley rats fed a
vitamin A-deficient diet for approximately 7 wk developed
vitamin A deficiency, as confirmed by the depletion of liver
retinol and
retinyl palmitate. Controls were fed the same diet supplemented with 24 mg/kg
retinyl acetate. The levels of expression of
RAR beta mRNA were approximately 80% lower in bladder, brain, liver, lung and trachea and those of
RAR gamma mRNA were approximately 50% lower in bladder, lung and trachea of rats fed the
vitamin A-deficient diet than in controls. The levels of expression of RAR alpha
mRNA were approximately 90% lower in brain and approximately 30% greater in liver, kidney, intestine and lung of rats fed the
vitamin A-deficient diet.
Vitamin A deficiency also resulted in reduced expression of
tissue transglutaminase in the bladder, lungs and trachea, which paralleled the effects observed for
RAR beta and
RAR gamma. When
vitamin A-deficient rats were subsequently fed a
retinol-deficient diet supplemented with
retinoic acid for 4 wk, the expression of
RAR (beta and gamma) and
tissue transglutaminase returned to the control levels. These results indicate that
vitamin A nutritional status in rats influences the expression of both RAR and
tissue transglutaminase in certain tissues.