Accumulation of peptide Tyr-D-Ala-Gly by choroid plexus during ventriculocisternal perfusion of rat brain.

Accumulation of Tyr-D-Ala-Gly (TAG) in choroid plexus was studied with ventriculocisternal perfusion of anesthetized rats. The choroid plexus of the lateral ventricles and the fourth ventricle accumulated TAG against a concentration gradient with regards to cerebrospinal fluid (CSF) but not plasma. This accumulation was inhibited by some metabolic inhibitors and peptides which had the same effect on accumulation of TAG in isolated choroid plexus. These results indicate that the active transport of TAG is present in the epithelium facing CSF. This active accumulation was affected by morphine. Reserpine, which is a chemical denervation of sympathetic nerves has no effect on the active accumulation of TAG. Thus, all these results suggest that, in vivo accumulation of TAG in choroid plexus during ventriculocisternal perfusion is similar to in vitro accumulation of TAG in isolated plexus.