Blood-brain barrier choline transport in the senescent rat.

Choline is an important membrane phospholipid constituent and a neurotransmitter precursor that is minimally synthesized in brain. The long-term maintenance of brain choline concentration is dependent on uptake from plasma, which occurs via saturable transporter at the blood-brain barrier. Previous studies have suggested that brain choline uptake declined with age. To reevaluate this, brain choline uptake in 3, 12, 24, and 28-month-old Fischer-344 rats was evaluated using the in situ brain perfusion technique. Minimal differences were found with uptake parameters differing by approximately 10% between aged and adult rats for tracer levels while similar trends were observed at higher choline concentrations. Further, estimated Vmax and Km values differed by <30% between the groups. The results suggest that blood-brain barrier choline uptake changes minimally with aging in the rat.