Neuroprotective effect of linagliptin against cuprizone-induced demyelination and behavioural dysfunction in mice: A pivotal role of AMPK/SIRT1 and JAK2/STAT3/NF-κB signalling pathway modulation.

Multiple sclerosis is a chronic inflammatory demyelinating central nervous system disorder leading to serious neurological deficits. Linagliptin, a dipeptidyl peptidase-4 inhibitor, recently showed neuroprotective properties against neurodegenerative diseases. This study investigated the possible neuroprotective effect of linagliptin against cuprizone-induced demyelination in mice and its potential early-remyelinating properties. C57Bl/6 mice were fed chow containing 0.7% cuprizone for 1 week, followed by 3 weeks of a 0.2% cuprizone diet. Linagliptin (10 mg/kg/day, p.o.) was given for 3 weeks starting from the second week. Linagliptin treatment improved behavioural and motor abnormalities induced by cuprizone, as demonstrated by open field, rotarod and grip strength tests. In parallel, linagliptin lessened the demyelination through enhancing Olig2 gene expression, as shown by increased myelin basic protein, myelin proteolipid protein levels and Luxol fast blue-staining intensity. Linagliptin attenuated cuprizone-induced oxidative stress by decreasing brain thiobarbituric acid reactive substances along with restoring reduced glutathione levels. Linagliptin exerted an anti-inflammatory effect by reducing brain tumor necrosis factor-alpha. Interestingly, linagliptin diminished phosphorylated JAK2, phosphorylated STAT3 and NF-κB p65 protein expression while up-regulating phosphorylated AMP-activated protein kinase (p-AMPK) protein and SIRT1 gene expression levels. In conclusion, linagliptin exerted a neuroprotective effect in mice with cuprizone-induced demyelination possibly by modulating AMPK/SIRT1 and JAK2/STAT3/NF-κB signalling pathways.