Vitamin E does not modify the insulin-induced memory impairment in mice during a novel object recognition task

Abstract

There has been conflicting reports on the effects of insulin on the brain generally and on learning and memory in particular. Insulin was reported to cause negative effect on the brain through increasing oxidative stress. This study examined the sub-acute effect of insulin treatment on short-term working memory and the possible modulatory role of vitamin E.Twenty four mice were grouped into four (n=6) treated for seven days thus: Control group- water; Insulin group- insulin (10 I.U./kg/day); Insulin+vitamin E group- insulin (10 I.U./kg/day) + vitamin E (100 mg/kg); Vitamin E group- vitamin E (100 mg/kg). Histological examination of brain tissue was conducted following assessment of memory using novel object recognition task at the end of the treatments. Data wereanalysed using SPSS, where in p values < 0.05 were taken as significant. Time spent on the novel object by the animals in all the treatment groups was significantly reduced (p<0.05) when compared with the control. Novel object recognition was significantly higher (p<0.05) in the untreated controls when compared with all the treatment groups. Discrimination ratio was > 0.05 in all the groups. Histological findings were normal in the treatment and control groups.In conclusion, the findings of this study show that vitamin E does not modulate insulin-induced impairment in long-term visuo-spatial and short-term working memory. Sub-acute combined or separate treatments with insulin and vitamin E do not affect brain histology.