Unveiling Remyelinating Properties of Roflumilast in CPZ-Induced Neuronal Demyelination in Mice.

Multiple sclerosis (MS) is a demyelinating disorder characterized by oligodendrocyte apoptosis, microglial activation at demyelination sites, with ROS production. These pathological processes are closely associated with phosphodiesterase-4 (PDE-4) activity. Roflumilast (ROFL), a selective PDE-4 inhibitor, has demonstrated neuroprotective effects in various central nervous system disorders. However, its specific role in MS pathogenesis remains to be fully elucidated. This study aims to investigate the effects of ROFL on oligodendrocyte maturation, microglial polarization and the impact on protein kinase A/cAMP-response element binding protein pathway. An MS model was induced in mice via dietary administration of cuprizone (CPZ) for 7 days, starting with 0.7% (w/w), followed by 0.2% for 5 weeks. Beginning in week 5, mice received ROFL (5 mg/kg/day, p.o) for 2 weeks. ROFL improved the motor abnormalities in the rotarod and open field tests. Together, ROFL downregulated the PDE4/cAMP-dependent pathway, exerting anti-inflammatory effects by suppressing NF-κB and TNF-α. Additionally, microglial polarization shifted toward the anti-inflammatory M2 phenotype, with CD163 increment, in contrast to the pro-inflammatory M1 marker CD83. Furthermore, ROFL's antioxidant capacity was evidenced by reduced malondialdehyde levels, replenishment of glutathione levels, and reduced phosphorylation of ERK1/2. Oligodendrocyte differentiation and maturation were enhanced, as indicated by elevated levels of proteolipid protein, myelin-associated glycoprotein, CNPase, and myelin basic protein. Remyelination was confirmed through Luxol fast blue staining, accompanied by reduced apoptotic marker, caspase-3, in oligodendrocytes. Collectively, these findings suggest that ROFL exerts neuroprotective effects and highlight the therapeutic potential of PDE-4 inhibition as a strategy for MS treatment.