DEVELOPMENTAL-CHANGES IN THE OPTIC-NERVE RELATED TO ETHANOL-CONSUMPTION IN PREGNANT RATS - ANALYSIS OF THE ETHANOL-EXPOSED OPTIC-NERVE

Visual impairment is one of the most common ophthalmic abnormalities i n fetal alcohol syndrome. Pathologic changes in optic nerve developmen t related to alcohol consumption could be involved in this dysfunction . In order to assess the consequences of pre- and postnatal exposure t o alcohol on the developing optic nerve, we administered an ethanol-co ntaining liquid diet (5% w/v) before and during gestation and througho ut lactation to rats and their offspring. A group of control animals w ere kept on a pair-fed isocaloric diet. The optic nerves were obtained at key stages from fetuses (21 days of gestation) and pups (4, 7, 14, 21 and 28 postnatal days). Samples of the optic nerve cross-section, behind the eyeball, were processed for analysis of gliogenesis, myelin ogenesis, axonal growth, and remodelling events, using light and elect ron microscopy. Qualitative, morphometric, and immunocytochemical anal yses, alternatively using anti-GFAP and anti-MBP antibodies, were carr ied out. Optic nerve cross-sections from prenatal and postnatal alcoho l-exposed rats showed a decrease in size. Ultrastructural alterations and retarded development in macroglial cells, optic axons, and myelin sheath were also observed. The most prominent abnormalities were: dama ge of cytoplasmic organelles and disorganization of cytoskeleton in as trocytes; a decrease in free ribosome density and nuclear membrane inc lusions in oligodendrocytes; and fragmentation of lamellae, aberrant m yelin sheaths and intralamellar inclusions in myelin. These findings s uggest that alcohol abuse during pregnancy is teratogenic to the optic nerve and closely related to the altered visual function. (C) 1993 Wi ley-Liss, Inc.