[Insulin resistance. Receptor and post-receptor abnormalities]

Area of Science:

• Molecular Endocrinology and Signal Transduction
• Metabolic Syndrome and Cardiovascular Disease

Context:

• Insulin action is initiated by insulin receptor binding, activating downstream signaling pathways including IRS-1 and PI-3-K.
• Insulin resistance (IR) is a complex phenotype associated with NIDDM, hypertension, obesity, and CHD, arising from defects in cellular signal transduction.
• Genetic and metabolic factors contribute to IR, with obesity being a primary driver of receptorial and post-receptorial defects.

Purpose:

• To elucidate the molecular mechanisms underlying insulin resistance.
• To explore the relationship between insulin resistance, NIDDM, obesity, and hypertension.
• To identify potential therapeutic targets and markers for insulin resistance.

Summary:

• Insulin receptor activation triggers signaling cascades involving IRS-1/2, G proteins, PLC, and PI-3-K.
• Non-insulin-dependent diabetes mellitus (NIDDM) results from defective insulin signal transduction, with IR being a key phenotype.
• Obesity-induced metabolic IR in skeletal muscle involves reduced insulin receptor expression and impaired downstream signaling.
• High erythrocyte Na(+)-Li+ counter-transport is identified as a biochemical marker for IR and hypertension.
• Several drugs, including metformin, ACE-inhibitors, and troglitazone, show potential in reducing IR.

Impact:

• Understanding IR mechanisms can lead to improved diagnostics and treatments for metabolic and cardiovascular diseases.
• Identification of biochemical markers like erythrocyte Na(+)-Li+ counter-transport aids in early detection and management.
• Pharmacological interventions targeting IR pathways offer therapeutic strategies for NIDDM, hypertension, and obesity.