Study summary · research use only
Passage of delta sleep-inducing peptide (DSIP) across the blood-cerebrospinal fluid barrier
Plain-language summary
Paraphrased from the published abstract below — not a verdict on whether anything works.
In this study using sheep and rabbits, researchers examined how 125I-labeled delta sleep-inducing peptide (DSIP) moves across the blood-cerebrospinal fluid (CSF) barrier. Using perfused in situ choroid plexuses of the lateral ventricles in sheep, arterio-venous loss of 125I-radioactivity suggested low-to-moderate permeability of the choroid epithelium to intact DSIP from the blood side. A saturable transport mechanism with Michaelis-Menten kinetics was found, with Kt = 5.0 +/- 0.4 nM and Vmax = 272 +/- 10 fmol.min-1, described as high affinity and very low capacity. In rabbits, ventriculo-cisternal perfusion showed no significant flux of intact DSIP out of the CSF. The authors state DSIP crosses the blood-CSF barrier but that the system lacks specific removal mechanisms found for most amino acids and several peptides.
Abstract
Unidirectional flux of 125I-labeled DSIP at the blood-tissue interface of the blood-cerebrospinal fluid (CSF) barrier was studied in the perfused in situ choroid plexuses of the lateral ventricles of the sheep. Arterio-venous loss of 125I-radioactivity suggested a low-to-moderate permeability of the choroid epithelium to the intact peptide from the blood side. A saturable mechanism with Michaelis-Menten type kinetics with high affinity and very low capacity (approximate values: Kt = 5.0 +/- 0.4 nM; Vmax = 272 +/- 10 fmol.min-1) was demonstrated at the blood-tissue interface of the choroid plexus. The clearance of DSIP from the ventricles during ventriculo-cisternal perfusion in the rabbit indicated no significant flux of the intact peptide out of the CSF. The results suggest that DSIP crosses the blood-CSF barrier, while the system lacks the specific mechanisms for removal from the CSF found with most, if not all, amino acids and several peptides.
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