Inability of insulin to maintain normal nerve function during high-frequency stimulation in diabetic rat tail nerves

Area of Science:

• Neuroscience
• Endocrinology
• Diabetology

Background:

• Diabetic peripheral neuropathy is a common complication of diabetes mellitus.
• Nerve dysfunction in diabetes affects nerve conduction velocity (NCV) and amplitude.
• The role of insulin in preserving nerve function under physiological stress is not fully understood.

Purpose of the Study:

• To investigate the effect of insulin on nerve function in acute experimental diabetes.
• To assess nerve response to long-term high-frequency stimulation (HFS) in diabetic rats with and without insulin treatment.

Main Methods:

• Acute diabetes was induced in rats using streptozotocin.
• Mixed tail nerves were subjected to long-term high-frequency stimulation (143 Hz for 20 min).
• Nerve conduction velocity (NCV) and peak-to-peak amplitude (P-Pamp) were measured in untreated and insulin-treated diabetic rats.

Main Results:

• Untreated diabetic rats exhibited decreased NCV and P-Pamp, with augmented P-Pamp depression during HFS.
• Insulin-treated rats maintained normal resting NCV and P-Pamp but showed similar P-Pamp depression during HFS as untreated rats.
• Insulin preserved resting nerve function but not functional capacity under HFS stress.

Conclusions:

• Insulin treatment in acute experimental diabetes preserves normal resting nerve conduction but does not prevent functional impairment during high-frequency stimulation.
• Axon membrane functional capacity under stress is compromised in diabetes, even with insulin therapy.
• Monitoring axon membrane function may be clinically relevant for managing peripheral neuropathies in diabetic patients.