Peripheral nervous system insulin resistance in ob/ob mice

Area of Science:

• Neuroscience
• Endocrinology
• Diabetology

Background:

• Peripheral nervous system (PNS) insulin signaling dysfunction is implicated in sensory neuron impairment and diabetic neuropathy.
• While in vitro studies show altered insulin signaling in dorsal root ganglion (DRG) neurons, in vivo evidence is limited.
• This study investigates in vivo insulin signal transduction in the PNS of insulin-resistant mice.

Purpose of the Study:

• To test the hypothesis that the PNS of insulin-resistant mice exhibits altered insulin signal transduction in vivo.
• To investigate the impact of insulin and IGF-1 on downstream signaling pathways in the DRG and sciatic nerve.
• To identify potential mechanisms contributing to PNS insulin resistance.

Main Methods:

• Utilized type 2 diabetic (ob/ob) and nondiabetic control mice.
• Administered intrathecal injections of insulin or insulin-like growth factor 1 (IGF-1).
• Evaluated downstream insulin signaling in the DRG and sciatic nerve via Western blot analysis.

Main Results:

• Insulin signaling abnormalities observed in other tissues of ob/ob mice were also present in the PNS.
• Insulin and IGF-1 stimulation robustly increased Akt activation in nondiabetic mice but showed a blunted response in ob/ob mice.
• Upregulated JNK activation and reduced insulin receptor expression were identified as potential contributors to PNS insulin resistance.

Conclusions:

• Altered insulin signaling in the PNS is confirmed in vivo.
• These findings support the role of PNS insulin signaling alterations in the pathogenesis of diabetic neuropathy.