Diabetes impairs DRG neuronal attachment to extracellular matrix proteins in vitro

Attachments of dorsal root ganglion (DRG) neurons from streptozotocin (STZ)-induced diabetic and normal C57BL mice to the following substrates were evaluated in vitro: a) poly L-lysine (PL), b) PL + type I collagen (CL-I), c) PL + type IV collagen (CL-IV), d) PL + laminin (LM) and e) PL + fibronectin (FN). After 6 h in culture, there was no significant difference in the average ratio of cells adhesive to PL between the diabetic (74.9%) and normal group of mice (75.6%). In the normal group, the addition of extracellular matrix (ECM) proteins such as CL-I, CL-IV, LM and FN to PL increased the ratios of cell attachment from 75.6% to nearly 90%. In the diabetic group, however, none of these proteins improved the attachment (the ratio changed from 74.9% to nearly 70%). Survival and neurite extension of attached cells after 48 h in culture were not different between the two groups. These results suggest that the cell-surface receptors, which enable DRG neurons to bind to the extracellular matrix proteins, are impaired by diabetes, resulting in being one of the causes of diabetic neuropathy.