The effect of insulin and Hypericum perforatum L.extract on the methabolic and behavioral alterations induced by experimental diabetes

In this thesis, alterations in the spontaneous locomotor activities, anxiety and depression levels, learning behavior and pain perceptions of STZ-diabetic rats were investigated, Diabetes mellitus (DM)-induced behavioral changes observed in these rats were tried to treat with insulin and Hypericum perforatum (Hypericacea) (Hyp) extract. Hyperglycemia, hyperphagia, polydipsia and weight loss were seen in STZdiabetic rats. Increased anxiety and depression levels, decreased spontaneous locomotor activities and learning levels were determined in diabetic animals. While mechanical hyperalgesia was seen in diabetic rats, changes of thermal pain perception from hyperalgesia to hypoalgesia were determined during six weeks period. Insulin treatment was found to decrease diabetic hyperphagia and polydipsia and increase body weights. In spite of the therapeutic effectiveness of insulin injection on altered depression, learning and pain levels, no effect on spontaneous locomotor activities and anxiety levels was observed. Hyp extract exhibited dose-dependent hypophagic, antidipsogenic, antidiuretic, antidepressant, analgesic, sedative effects and increased learning levels of healthy rats. Extract, administered to diabetic rats, was shown to decrease hyperglycemia, hyperphagia and polydipsia and to prevent the loss of body weights. Treatment with extract was found to decrease elevated depression and anxiety levels, increase diminished spontaneous locomotor activities and learning levels and elicite analgesic activities. It was concluded by this investigation that central nervous system complications of DM show a progressive nature, chronic insulin treatment is not enough to prevent these complications alone. The extract prepared from Hyp exhibited therapeutic effects on these complications via both its antidiabetic and central nervous system effects