The ınvestıgatıon of effects of thıamıne on theapoptotıc alteratıons ın the experımental dıabetıc ratbraın tıssue

Diabetes mellitus is a hyperglycemic metabolic, chronic disorder characterized by high blood glucose levels, that result from deficiency of insulin secretion or effects of insulin or both of them. Overtime diabetes cause cerebral changes which appear as neurochemical, electrophysiological, structural and cognitive disorders.Thiamin or vitamin B1 is a member of the B vitamin family. Thiamine, known as B1 vitamin, acts in thiamin pyrophosphate form during metabolic processes. Thiamin is necessary in the catabolism of Carbonhidrates and most of amino acid. It is observed in experimental studies that thiamin has antioxidant properties. In this study, it was investigated the protective effects of thiamin on apoptotic changes of rat brain in a diabetic rat model induced streptozosin.Twenty-one adult male Wistar albino rats, with body weigth of 238 ± 8 gr, were used. All rats were recived Standard chow and water ad libitum during experimental period. Rats were randomly divided into three groups with seven rats per gruop. Rats in group I, used as control, were recived just standard chow and water ad libitum. Rats in group II and Group III were injected intraperitoneal streptozotocin (50mg/kg) to establish diabetes mellitus rat model. After confirmed of experimental diabetes mellitus, diabetic animals in Group II were recived just standard chow and water wheras diabetic rats of group III were recived thiamin (25mg/kg/day, oral) for six week.After treatment for six week, all of rats weighed and then decapitated. The brains were quickly removed and fixed in 10% formalin for 24 h and embedded with parafin. Parafin blocks were sliced into 5µm sections to observe apoptotic changes using TUNEL and immunohistochemical(Bax) tecniques.Bax immunereactivity of group II(DM) brain tissues increased significantly. The expression of Bax in group III (DM + thiamin) was generally similar to that in group I controls and less than group II.Prevalance of TUNEL ? positive cells consistent with prevalance of Bax-positive cells in all three groups. In the light microscopic examination, there was a significantly greater number of TUNEL-positive cells in the group II (DM) than in the group I. Brain sections of thiamine ?treated groupIII had less TUNEL-positive cells compared to brain sections of diabetic group II. There was no significant difference between the group III and group I.In conclusion, it is observed that thiamin has protective effects againest DM-induced apoptotic changes in the brain tissues. To prevent DM-induced cerebral complications, thiamine treatment may be useful and there is necessity advanced research about this.Key Words: Diabetes mellitus, Thiamine, brain, apoptosis