PKC Mediates endogenous inhibition of myelin repair in the context of local demyelination induced in mice optic chiasm

Axon regeneration in adult CNS is limited by the presence of inhibitory proteins associated with myelin. Although blocking PKC activity attenuates the ability of CNS myelin to inhibit neurite outgrowth, the role as well as mechanisms underlying the remyelination inhibition in CNS are still largely unknown. Considering the role of PKC in axonal regeneration and the vulnerability of optic chiasm in multiple sclerosis (MS), we assessed the effect of PKC inhibition on remyelination of lysolecithin induced demyelinated optic chiasm. Demyelination was induced by stereotaxic intra-chiasmatic injection of 1µl lysolecithin (%1) in male mice. Intracerebroventricular daily injection of a PKC inhibitor (GO6976) was done for 14 days post-lesion. Demyelination and remyelination patterns in optic chiasm were confirmed through histological verification and electrophysiological study using Luxol fast blue staining and visual evoked potentials (VEP) recording, respectively. In lysolecithin treated animals, demyelination was mostly marked at days 3 and 7 post-lesion and an incomplete remyelination occurred at day 14 post-lesion. VEP recording showed increased P-latency at the days 3 and 7 post-lesion while it partially decreased at day 14. Following the inhibition of PKC, while the extent of demyelination and P-latency slightly decreased at the days 3 and 7 post-lesion, it recovered at day 14. VEP recording data were confirmed by histological verification. Inhibition of PKC activity could represent a potential therapeutic approach for stimulating the remyelination process in the context of multiple sclerosis.