RESUMO
This research was conducted to investigate two main aims; the first aim was to find if there is a relationship between insulin resistance [IR] and retinol binding protein 4 [RBP4]. The second aim was to use berberis vulgaris extract and vitamin A as protective and/or curative agents against insulin resistance. IR was developed by feeding the female rats a high fat diet [HFD] for six weeks then treating or protecting them with b. vulgaris extract [0.2 g/Kg body weight] or vitamin A [12.8 Micro g/Kg/day] for two weeks. HFD intake elevated insulin level and RBP4 expression that associated with hyperglycemia and hyperlipidemia. Co-administration of vitamin A and B. vulgaris extracts reduced blood glucose level, insulin, body weight and RBP4 expression before, during and after HFD. Furthermore, vitamin A reduced the blood glucose, triglycerides [TG] and cholesterol levels. IR syndrome associated with the RBP4 alteration that gives high indication about the role of RBP4 expression in the IR progression and development. Furthermore, the treatment with vitamin A and/or b. vulgaris alleviated the IR syndrome through the action on RBP4 and Insulin secretion. On the other hand, vitamin A must be avoided for the predisposed IR and prediabetic patients