Gene profiling in the dynamic regulation of the lifespan of the myelin sheath structure in the optic nerve of rats

Aging of the nervous system leads to impairments in cognition and motor skills, and is a major risk factor for several neurological disorders. Recently, numerous nerve function deficits that appear with aging have been found to be a consequence of myelin abnormalities; however, the genetic mechanism of the age-related alterations in the myelin sheath has not yet been fully elucidated. In the present study, the morphology of the myelin sheath in the optic nerve of rats was analyzed at 10 time-points throughout life. Marked alterations in the myelin sheath were observed in aging and aged optic nerves, and these became progressively more severe with time. To determine the biological processes affected by aging in the myelin sheath, the age-related profiling of the myelin sheath in rat optic nerves was established using microarray hybridization at 10 time-points throughout life, between birth and senescence. From the results, 3,826 transcripts associated with the age-related alterations in the myelin sheath of the optic nerve were identified . It was found that the biological processes most significantly altered by aging were lipid metabolism, the immune response and transmitter transport. This suggests that the downregulation of lipid synthesis genes and the upregulation of immune and neurotransmitter trans- port genes in aging may be the genetic basis for the age-related alterations observed in the myelin sheath.