title: Abnormal incorporation and utilization of alpha-tocopherol in erythrocyte membranes of streptozotocin-induced diabetic rats.
abstract: Alpha-tocopherol is a well-known lipophilic-free radical scavenger that is mainly localized in biomembranes. In this study, we investigated the changes in the incorporation and utilization of alpha-tocopherol in erythrocyte membranes of streptozotocin-induced diabetic rats and the effects of insulin to control hyperglycemia on these changes. Diabetes was experimentally induced by the injection of streptozotocin (60 mg/kg, i.v.). Blood was collected to determine the concentrations of alpha-tocopherol and its oxidative metabolite (alpha-tocopherolquinone) in plasma or erythrocyte membranes after streptozotocin injection. In streptozotocin-induced diabetic rats, alpha-tocopherol concentrations were decreased in erythrocyte membranes and increased in plasma. The ratio of alpha-tocopherol in erythrocyte membranes to that in plasma, which reflects the incorporation of alpha-tocopherol into erythrocyte membranes, was dramatically decreased in streptozotocin-induced diabetic rats. Moreover, the ratio of alpha-tocopherolquinone to alpha-tocopherol in erythrocyte membranes, which reflects the utilization of alpha-tocopherol, was increased in streptozotocin-induced diabetic rats. These changes were prevented by insulin to control hyperglycemia. These findings suggest that the abnormalities in the incorporation and utilization of alpha-tocopherol in erythrocyte membranes of streptozotocin-induced diabetes can be restored to normal by insulin therapy to control hyperglycemia.
authors.affiliation: Department of Geriatrics, Tokyo Medical University, Shinjuku, Japan.
authors.forename: Kazushi
authors.initials: K
authors.lastname: Shinozaki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Takeda
authors.forename: Masato
authors.initials: M
authors.lastname: Inazu
authors.forename: Teruhiko
authors.initials: T
authors.lastname: Matsumiya
authors.forename: Masaru
authors.initials: M
authors.lastname: Takasaki
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism; D001835:Body Weight / Q000187:drug effects; D003921:Diabetes Mellitus, Experimental / Q000097:blood* / Q000188:drug therapy; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000378:metabolism*; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D013311:Streptozocin / Q000008:administration & dosage; D014810:Vitamin E / Q000031:analogs & derivatives* / Q000097:blood; D024502:alpha-Tocopherol / Q000097:blood* / Q000378:metabolism
chemical_list: D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin; D014810:Vitamin E; D013311:Streptozocin; C002421:tocopherylquinone; D024502:alpha-Tocopherol