INDUCTION OF P75(NGFR) IN HUMAN DIABETIC NEUROPATHY

In this immunohistochemical study we investigated the expression of lo w-affinity NGF receptor (p75(NGFR)) in peripheral nerves from 16 patie nts with type I or type II diabetes mellitus. Fourteen nerves from age -and sex-matched normal individuals and nine nerves from non-diabetic patients with ischemic neuropathy served as controls. All nerve sample s were preliminarily examined by standard histology, fiber teasing and electron microscopy. Increased p75(NGFR) immunoreactivity was detecta ble within the endoneurium of cross-sections from ischemic and particu larly from diabetic nerves. Immune-teasing demonstrated that p75(NGFR) immunostaining was distributed along the entire length of isolated ne rve fibers undergoing axonal degeneration. Quantitative assessment of p75(NGFR) immunoreactivity, performed by histospectrophotometry and ex pressed as percentage of adsorbance, was 21.20 +/- 3.50 in nerves from diabetic patients, 13.35 +/- 3.62 in nerves from non-diabetic patient s with ischemic neuropathy and 9.02 +/- 2.75 in normal controls. The i ncreased expression of p75(NGFR) in diabetic nerves is consistent with an axonopathic defect and further suggests involvement of NGF and oth er neurotrophins in the pathogenesis of human diabetic neuropathy.