Increased ciliary length of oligodendrocytes in anterior optic nerve with ageing

Abstract

Purpose : Little is known regarding the role of primary cilia, in aged oligodendrocytes (OLGs), which tend to be dysfunctional in neurodegenerative diseases. To investigate if primary cilia in aged OLGs might be involved in the age-related degeneration of vision, we examined the length and frequency of OLG primary cilia in the optic nerves of young and aged C57BL/6 wild-type mice.

Methods : Cryosections of the optic nerve and optic chiasm were prepared from the eyes of 8 young and aged C57BL/6 mice (3 and 20 months). Samples were immunostained with anti-Arl13b, anti-Oligo2, and anti-MBP to visualize primary cilia and OLGs, and imaged by confocal microscopy. Images of the anterior and posterior optic nerve and optic chiasm were examined, and statistical analysis was performed using the One-way ANOVA and Student’s t-test.

Results : The ciliation of Oligo2-positive OLGs in the anterior optic nerve was 8.6 ± 5.9% and 7.7 ± 4.1% in young and aged mice, respectively. The ciliation of Oligo2-positive OLGs in the optic chiasm was 5.4 ± 4.5% and 5.6 ± 3.8% in young and aged mice, respectively. There were no significant changes in ciliation between the young and aged groups. In 3-month-old mice, the mean ciliary length of Oligo-2-positive OLGs was similar in the anterior and posterior optic nerve (1.12 ± 0.80 um and 1.25 ± 1.06 um, respectively). In 20-month-old mice, the mean ciliary length was significantly greater in the anterior optic nerve than in the posterior optic nerve (1.73 ± 1.26 μm and 1.00 ± 0.38 μm, P<0.05, respectively).

Conclusions : We reported a novel regional difference in OLG primary cilia length in the optic nerves of aged mice, suggesting that primary cilia may play a role in OLGs and myelination disorders.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.