The effect of low-dose insulin on mechanical sensitivity and allodynia in type I diabetes neuropathy

The pathogenesis of diabetic neuropathy is multifactorial, but in general hyperglycemia through polyol and protein glycation pathways is considered to be a key etiol\ogical factor. Most likely insulin deficiency, in experimentally induced type 1 diabetes, contributes to the development of diabetes neuropathy. The aim of this study was to evaluate the in vivo behavioral effect of low-dose insulin on diabetic neuropathy in rats through behavioral testing in hyperglycemic conditions. Mechanical sensitivity and allodynia were tested in streptozotocin (STZ)-induced diabetic rats. After diabetes and neuropathy induction, treatment with low-dose insulin normalized behavioral test results in 37 days, while severe hyperglycemia persisted. Although this study provided no evidence about the role of hypoinsulinemia in the etiology of diabetes neuropathy, the results confirmed that an insulin deficit with impaired insulin signaling and neurotrophic support, rather than hyperglycemia, plays an essential role in the pathophysiology of painful diabetic neuropathy. (c) 2007 Elsevier Ireland Ltd. All rights reserved.