Perineurium inflammation and altered connexin isoform expression in a rat model of diabetes related peripheral neuropathy

Diabetes related peripheral neuropathy involves both somatic and autonomic nerves and leads to an array of debilitating abnormalities. Mechanisms may include decreased neuronal conductance, reactive oxygen species, and decrea sed performance of the perineurium blood-nerve barrier. Here we studied the perineurium characteristics of the dorsal penile nerve in a rat model of d iabetes related peripheral neuropathy. Immunohistochemistry showed extensiv e and perineurial cell-specific nitric oxide synthase2 staining in diabetic animals as compared to age matched controls (P < 0.05); however no apparen t difference in immunostaining pattern was observed for 3-nitrotyrosine (a stable biomarker of peroxynitrite formation). Significant reductions in con nexins 32 and 26 were seen in the diabetic perineurium with no detectable l evels of connexin 43 in either control or diabetic dorsal nerve. These data provide new evidence of perineurial cell inflammatory responses and altere d gap junction protein expression during diabetes related neuropathies and suggests that strategies to protect this cell type may have therapeutic val ue. (C) 2001 Published by Elsevier Science Ireland Ltd.