Additional evidence that small amounts of a peptide can cross the blood-brain barrier.
Kastin. A J AJ; Nissen. C C; Schally. A V AV; Coy. D H DH
Key Findings
- The antibody used to detect DSIP needs almost the entire 9‑amino‑acid sequence, so the test measures mostly intact peptide.
- Injecting 200 µg of DSIP into the carotid artery doubled the amount of peptide detected in the brain shortly after injection.
- The brain‑to‑blood radioactivity ratio for labeled DSIP was much higher than for a control molecule (inulin), indicating genuine crossing of the blood‑brain barrier.
Practical Outcomes
- For biohackers, this suggests that peripheral (e.g., subcutaneous or intranasal) dosing of DSIP could potentially influence brain function, but only a small fraction actually gets in. It highlights the need for higher or repeated dosing if the goal is central effects, and underscores that more research is needed to define effective, safe protocols.
Summary
A study showed that when a small peptide called delta‑sleep inducing peptide (DSIP) is injected into a rat's bloodstream, some of it can cross the blood‑brain barrier and reach the brain in almost its whole form. This means that giving DSIP outside the brain could still have direct effects inside the brain.
Abstract
It was determined that an antiserum against delta-sleep inducing peptide (DSIP) required eight of the nine constituent amino acids for antigenic activity. Measurement by this radioimmunoassay (RIA) or DSIP-like material in the rat brain, therefore, would necessarily involve almost the entire molecule present in essentially intact form. Injection of 200 microgram DSIP into the carotid artery of rats resulted in a doubling of brain levels of peptide as measured shortly afterwards by RIA. The brain tissue to plasma ratio of radioactivity in rats injected with labeled DSIP was much higher than that in rats injected with labeled inulin; this suggests that the increased amount of material measured by RIA was not merely trapped in the blood vessels. Thus, the results indicate that a small amount of essentially intact peptide can cross the blood-brain barrier. This could represent one of the mechanisms by which central effects of peripherally injected peptides can be exerted.
Study Information
pubmed
1979
1979-12-01T00:00:00.000Z
10.1016/0091-3057(79)90269-7
83
11