In situ transverse elasticity and blood perfusion change of sciatic nerves in normal and diabetic rats.

BACKGROUND

Diabetic neuropathy is the most pervasive complication of diabetes mellitus and its etiopathology is not completely elucidated. The existing literature focuses on the histological and structural changes as well as the longitudinal mechanical properties of nerves. The main objective of this study is to investigate the in situ transverse biomechanical properties and changes of microcirculation of sciatic nerves in diabetic and normal control rats.

METHODS

Quasi-static circular compression experiments were conducted on sciatic nerves of six normal and six diabetic Wistar rats. Local blood perfusion during the compression was also measured by laser Doppler flowmetry. The compressive stress and strain were estimated, in order to calculate the apparent Young's modulus. The impact of diabetes on peripheral nerves was examined by analyzing the transverse elasticity and microcirculation changes.

FINDINGS

The mean transverse apparent Young's modulus of the sciatic nerves in diabetic rats was 210.7 kPa, which was nearly two times greater than that of normal controls (116.3 kPa). The pressure threshold that blood perfusion started to decrease in diabetic rats (24.1 mm Hg) was smaller than in the normal controls (47.1 mm Hg).

INTERPRETATION

These results suggest that the sciatic nerve was stiffer in the diabetic rats. The structural changes in microvessels might lead to earlier decrease of blood perfusion in diabetic nerves under radial compression. These results provide information about the biomechanical and microcirculation changes of peripheral nerves inflicted by diabetes and may also serve as a reference for clinical nerve repair and regeneration for patients with diabetic neuropathy.