Neurotoxic Effects of Dexamethasone in Rat Optic Nerve Maturation

Abstract

Abstract: : Purpose:To study the histological effects of repeated doses of dexamethasone on the developing optic nerve in a rat model of prematurity. Methods: Forty–one Srague–Dawley rats pups were randomly assigned into two groups to be administered respectively dexamethasone (n=22) or saline solution (n=19) for five days after birth. The optic nerves were examined at P6, P10 and P15 by immunostaining using specific markers of the varying stages of white matter cells’ maturation. The preoligodendrocytes were detected with anti–O4 antibody, the mature oligodendrocytes were detected with anti–MBP, the astrocytes were detected with anti–GFAP and cell death apoptosis with anti–cleaved caspase3 antibodies. Results: Compared to the control group, the group treated with dexamethasone appeared to have significantly less preoligodendrocyte markers but more astrocyte cells markers. In the corticoid group, oligodendrocytes did not express MBP even at P15. Caspases was not different between the two groups. Conclusions: Myelinisation of optic nerve appeared delayed in our rat model. We suggest that repeated doses of dexamethasone may influence optic nerve maturation and could eventually compromise visual functions’ acquisitions in premature infants. The interest of regular visual evaluation infants appears essential

Keywords: neuro-ophthalmology: optic nerve • anatomy • infant vision