Humanin affects object recognition and gliosis in short-term cuprizone-treated mice.

Humanin (HN) is a 24-residue peptide that manipulates cell survival under various stresses. A highly potent HN derivative, HNG, reduced amyloid burden and neuroinflammation and suppressed cognitive impairment in Alzheimer's disease model mice. Cuprizone (CPZ), a copper chelator, provokes demyelination in the central nervous system of mice. A shorter (one week) exposure to CPZ induces schizophrenia-like behavior and glial activation prior to demyelination. We tested the effect of HNG on these short-term responses to CZP in mice. Intraperitoneal injection of HNG for one week improved object recognition memory but not working memory in CPZ-treated mice. Quantitative PCR analyses showed that HNG significantly suppressed CPZ-induced activation of microglia, but did not alter the reduced level of a myelin-specific transcript. These results suggest that HN can suppress neuroinflammation and the associated cognitive deficit in a wider range of neurological disorders beyond Alzheimer's disease.