Effects of Vitamin D in Long-Term Ovariectomized Rats Subjected to Chronic Unpredictable Mild Stress: BDNF, NT-3, and NT-4 Implications.

The purpose of this study was to explore the antidepressant-like effects of vitamin D at different doses (1.0, 2.5, and 5.

Rac-1 superactivation triggers insulin-independent glucose transporter 4 (GLUT4) translocation that bypasses signaling defects exerted by c-Jun N-terminal kinase (JNK)- and ceramide-induced insulin resistance.

Insulin activates a cascade of signaling molecules, including Rac-1, Akt, and AS160, to promote the net gain of glucose transporter 4 (GLUT4) at the plasma membrane of muscle cells. Interestingly, constitutively active Rac-1 expression results in a hormone-independent increase in surface GLUT4; however, the molecular mechanism and significance behind this effect remain unresolved. Using L6 myoblasts stably expressing myc-tagged GLUT4, we found that overexpression of constitutively active but not wild-type Rac-1 sufficed to drive GLUT4 translocation to the membrane of comparable magnitude with that elicited by insulin.

Direct and macrophage-mediated actions of fatty acids causing insulin resistance in muscle cells.

Obesity is associated with insulin resistance and increased risk for developing type 2 diabetes. Enlarged adipocytes develop resistance to the anti-lipolytic action of insulin. Elevated levels of fatty acids in the plasma and interstitial fluids lead to whole-body insulin resistance by disrupting normal insulin-regulated glucose uptake and glycogen storage in skeletal muscle.