Small Rises in Plasma Choline Reverse the Negative Arteriovenous Difference of Brain Choline

Abstract

The concentrations of free choline in blood plasma from a peripheral artery and from the transverse sinus, in the CSF, and in total brain homogenate, have been measured in untreated rats and in rats after acute intraperitoneal administration of choline chloride. In untreated rats, the arteriovenous difference of brain choline was related to the arterial choline level. At low arterial blood levels (less than 10 microM) as observed under fasting conditions, the arteriovenous difference was negative (about -2 microM), indicating a net release of choline from the brain of about 1.6 nmol/g/min. In rats with spontaneously high arterial blood levels (greater than 15 microM), the arteriovenous difference was positive, implying a marked net uptake of choline by the brain (3.1 nmol/g/min). The CSF choline concentration, which reflects changes in the extracellular choline concentration, also increased with increasing plasma levels and closely paralleled the gradually rising net uptake. Acute administration of 6, 20, or 60 mg of choline chloride/kg caused, in a dose-dependent manner, a sharp rise of the arterial blood levels and the CSF choline, and reversed the arteriovenous difference of choline to markedly positive values. The total free choline in the brain rose only initially and to a quantitatively negligible extent. Thus, the amount of choline taken up by the brain within 30 min was stored almost completely in a metabolized form and was sufficient to sustain the release of choline from the brain as long as the plasma level remained low. We conclude that the extracellular choline concentration of the brain closely parallels fluctuations in the plasma level of choline.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma choline concentration varies with different dietary levels of vitamins B6, B12and folic acid in rats maintained on choline-adequate diets

“…During the entire experimental period, body weight (F (1,30) ¼ 0·02, P¼ 0·89) and food intake (F (1,14) ¼ 2·92, P¼0·11) were unaffected by dietary B vitamins.…”

“…After the supplementation period, analyses of plasma samples revealed that plasma free choline concentration was up to 10 % higher in rats fed the B vitamin-enriched diet than in rats that were continued on the B vitamin-poor diet (F (1,30) ¼ 9·52, P, 0·005; Fig. 1(a)).…”

Magnetic Resonance Spectroscopy Reveals an Impaired Brain Metabolic Profile in Mice Resistant to Cerebral Malaria Infected with Plasmodium berghei ANKA

“…GPC can be degraded to free choline that is able to cross the BBB (37). Thus, the decrease in brain GPC could result from a compensatory mechanism to replenish blood choline used by the parasite to proliferate, because choline concentration in brain closely parallels choline fluctuations in plasma (38).…”

Choline Release and Inhibition of Phosphatidylcholine Synthesis Precede Excitotoxic Neuronal Death but Not Neurotoxicity Induced by Serum Deprivation

“…In brain, Cho is stored almost completely in a metabolized form (26). Intracellular free Cho concentration is kept low because once Cho is inside the cell, it is rapidly phosphorylated by choline kinase (26,27).…”