title: Sustained hypomyelination and high serum thyroid hormone in aged black tremor hamster.
abstract: Oligodendrocytes and myelin in the corpus callosum of black tremor and normal hamsters aged over 1.5 years were ultrastructurally examined to determine the myelination index (ratio of myelin thickness/diameter of axon), percentage of naked axons, and proportions of oligodendroglial subtypes (light, medium and dark). The mutant hamsters were remarkably hypomyelinated, with a low myelination index and a high proportion of naked axons, and high proportions of the dark subtypes. Serum concentrations of thyroid hormones (T3 and T4) in 6-week-old mutant hamsters were 2-fold (T3) to 3-fold (T4) higher than those of age-matched normal animals. However, in the aged animals (over 1.5 years old) only T4 levels of the mutant hamsters were higher in the mutant than normal hamsters. The black tremor hamsters were hypomyelinated throughout their life and high serum level of thyroid hormones might have played a role in the hypomyelination.
authors: Laboratory of Comparative Pathology, Department of Veterinary Clinical Sciences, Hokkaido University Graduate School of Veterinary Medicine, Sapporo 060-0818, Japan.
authors: Hyoung-Ook
authors: HO
authors: Kim
authors: Takashi
authors: T
authors: Kimura
authors: Kenji
authors: K
authors: Ochiai
authors: Hajime
authors: H
authors: Yazawa
authors: Chitoshi
authors: C
authors: Itakura
authors: Takashi
authors: T
authors: Umemura
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D001369:Axons / Q000648:ultrastructure*; D006224:Cricetinae; D005260:Female; D008297:Male; D023421:Models, Animal; D009154:Mutation; D009186:Myelin Sheath / Q000648:ultrastructure*; D009836:Oligodendroglia / Q000145:classification / Q000648:ultrastructure; D013963:Thyroid Hormones / Q000097:blood*
chemical_list: D013963:Thyroid Hormones