Increases in the concentration of brain alpha-bungarotoxin binding sites induced by dietary choline are age-dependent

We have previously reported that a diet supplemented with choline induces an increase in the concentration of a brain nicotinic-like receptor, as measured by alpha-bungarotoxin (BuTX) binding. Here we report the effects of choline administered in the drinking water on BuTX binding in the cortex, midbrain and brainstem of rats at 3 ages. In comparison with animals fed a choline-free diet, choline supplementation produced increases averaging 50% in 23-day-old rats and increases of approximately 30% in 60-day-old rats. Increases were also found in 6-month-old animals (averaging 16%), but the differences were generally not statistically significant. The mechanism responsible for the increase in the concentration of BuTX binding sites following the administration of dietary choline is not known, but the results are discussed in terms of choline as a precursor for the biosynthesis of acetylcholine and the biosynthesis of phospholipids. These data indicate that the administration of dietary choline is not likely to be effective in reversing cholinergic deficits by increasing the concentration of nicotinic-like receptors in aging rats.