Chronic dietary choline influences the permeability of nerve cell membranes as revealed by in vivo Rb+ uptake and release

The effect of chronic choline supplementation on the in vivo Rb⁺ uptake and release of rat brain cortical cells was investigated. Adult (11 months old) and old (22 months old) controls as well as old (22 months old) female rats treated with choline (∼ 100 mg/day in the drinking water) by the age of 11 months, were used. All the animals received a daily dose of 30 mg RbCl/100 g body weight for 14 days, given intraperitoneally, half in the morning, half in the evening. After discontinuation of the RbCl treatment, the animals were killed at intervals of 2, 4, 9 and 16 days, respectively. The intracellular Rb⁺ and K⁺ contents were analyzed by energy dispersive X-ray microanalysis, whereas concentrations of these two elements were determined by atomic absorption spectrophotometry in the cerebrospinal fluid. Old animals accumulate more Rb⁺ than the adult ones at any time taken into account. Choline treatment was able to reduce the amount of accumulated Rb⁺ in the old rats. Rb⁺-discrimination ratios calculated on the basis of Rb⁺ and K⁺ contents of both cortical cells and cerebrospinal fluid, is higher in old rats as compared to both adult and old choline treated rats. Present findings support that chronic choline treatment is effective improving the passive membrane permeability of nerve cells for Rb⁺ (and K⁺) in the old animals.