Diabetic Neuropathy: Abnormalities of Schwann Cell and Perineurial Basal Laminae. Implications for Diabetic Vasculopathy

Abstract

During Wallerian degeneration, the Schwann cell basal laminal ensheathment around myelinated nerve fibres remains after the removal of myelin and axonal debris, forming a corrugated tube within which Schwann cell proliferation takes place. In nerve biopsies from patients with diabetic neuropathy, such residual basal laminal tubes tend to be circular rather than corrugated and appear to be more persistent during regeneration; this suggests increased rigidity and durability. These changes could be the result of increased cross-linkage of type IV collagen or alterations to other components of the basal lamina. A similar mechanism may be responsible for the thickening of perineurial basal laminae and the reduplication of basal laminae around endoneurial capillaries in diabetic patients; such reduplication may lead to reduced compliance of the vessel walls and impaired vascular perfusion.

Integrins and the extracellular matrix: Key mediators of development and regeneration of the sensory nervous system

“…Sensory symptoms in diabetic neuropathy may include numbness, heightened sensitivity, pain and/or dysesthesia (abnormal sensations such as burning, itching and pins and needles). Structural, biochemical, and electrophysiological abnormalities develop in the peripheral nerve, including Schwann cell pathology, distal degeneration of myelinated and unmyelinated axons and ECM abnormalities, notably increased endoneurial collagen, reduplication of basement membranes around endoneurial capillaries, and a thickening of basement membranes (Sharma and Thomas, 1974;King et al, 1989;Bradley et al, 2000).…”

Alterations in mRNA Expression of Myelin Proteins in the Sciatic Nerves and Brains of Streptozotocin-induced Diabetic Rats

“…The fundamental basis of abnormalities in the central and peripheral nervous systems affected by hyperglycemia could, partly, comprise the accompanying axonal atrophy and demyelination [1,11,12]. Myelin proteins are considered to have myelin functions together with lipid molecules in myelin, and thus it is suspected that alterations in protein components cause functional disorders in central and peripheral nerve myelin.…”

Nerve conduction block in diabetic rats using high-intensity focused ultrasound for analgesic applications

“…The CAPs and SAPs of nerves from control rats in vitro were temporarily and incompletely suppressed by 4 s of continuous HIFU at an intensity of 2290 W cm 22 . The CAPs and SAPs were inhibited by 20% 2 min after HIFU exposure, and maximal suppression was seen (approximately 50%) at 10 min, with 30% suppression at 8 min.…”