In rats, the anxiety‑relief peptide Selank didn’t change normal stomach blood flow but helped bring blood flow back to normal when it was lowered by an NSA‑drug. Tiny amounts of Selank (10⁻¹²‑10⁻¹⁴ M) made the gut’s lymph vessels contract stronger and faster, while larger amounts (10⁻⁶‑10⁻¹⁰ M) made them contract stronger but slower. These effects might be part of why Selank can protect against ulcers, but the work was done in anesthetized rats, not people.

The influence of a new heptapeptide Selank on microcirculation in anesthetized white rats was investigated. Selank (Thr-Lys-Pro-Arg-Pro-Gly-Pro) is a new synthetic anxiolytic which exerts obvious antiulcerogenic action and promotes healing of experimental ulcers. Action of the peptide on gastric blood flow in the stomach by using the method ofhydrogenic clearance and Selank action on mesenteric lymphatic contractility by microscopical observation in situ, were studied. Selank fail to influence basal gastric blood flow but it can normalize blood flow reduced by indomethacin. The study of dose-depended of Selank effect on lymphatic vessels contractility showed that its low concentration (10(-12)--10(-14) M) enhanced amplitude and increase frequency of lymphatic vessel contractions which indicates an enhancement of lymphatic flow. The high doses of peptide (10(-6)--10(-10) M) also augmented the contraction amplitude but decreased its frequency. The maintenance of adequate blood flow and lymphatic vessel contractility can be one of the mechanisms of the Selank antiulcerogenic properties.