Spontaneous diabetes
Several spontaneous or genetically derived diabetic rat models are commonly used in pharmacological and pathological studies, including Zucker fatty rats, ZDF rats, SHR/N-cp rats, JCR/LA-cp rats, and Otsuka Long Evans Tokushima fatty (OLETF) rats.115 The OLETF rats show typical symptoms of T2DM, including hyperinsulinemia, hyperglycemia, insulin resistance, hypertriglycemia, and mild obesity. A recent study by Zhao et al109 further reported that LBPs improved insulin resistance via translocation and activation of GLUT4 in OLETF rats. The results showed that LBPs caused translocation of the GLUT4 to the cell surface, which in turn stimulated glucose uptake, and the effect was sensitive to wortmannin, an inhibitor of PI3K, and SB203580, an inhibitor of p38 mitogen-activated protein kinase (p38 MAPK).109 Furthermore, the effects of LBPs on p38 MAPK activities were abrogated by pretreatment of rat adipocytes using SB203580. LBPs improved insulin resistance via translocation and activation of GLUT4 in OLETF rats, and the activation of PI3K and p38 MAPK contributed to these effects.109