Paper Title
Expressions of Microglia, BDNF and DREAM Proteins in Painful and Non-Painful Variants of Diabetic Neuropathy Rats

Abstract
Painful (PDN) and non-painful (non-PDN) variants of diabetic neuropathy produce distinctive clinical syndromes. This study aimed to investigate expressions of microglia and signalling molecules brain-derived neurotrophic factor (BDNF) and downstream regulatory element antagonist modulator (DREAM) proteins in spinal cord of streptozotocin-induced diabetic neuropathy rats. Thirty male Sprague-Dawley rats (200-230g) was randomly assigned into three groups: (1) control (non-diabetic), (2) PDN and (3) non-PDN. The rats were induced with diabetes mellitus (DM) by intraperitoneal injection of streptozotocin (60 mg/kg) whilst control rats received citrate buffer as vehicle. Four weeks post-diabetic induction, the rats were induced with chronic inflammatory pain by intraplantar injection of 5% formalin and pain behaviour responses were recorded and assessed. Three days later, the rats were sacrificed and lumbar enlargement region of spinal cord was collected. The tissue was immunoreacted against OX-42 (microglia), BDNF and DREAM proteins, which was also quantified by western blotting. PDN rats exhibited increased pain behaviour score peripherally and centrally with marked increase of spinal activated microglia, BDNF and DREAM proteins expressions compared to control group. In contrast, non-PDN demonstrated a significant reduction of pain behaviour score peripherally and centrally with significant reduction of spinal activated microglia, BDNF and DREAM proteins expressions. Different expression of microglial, BDNF and DREAM proteins might possibly contribute to different pain behaviour responses in PDN and non-PDN. Index Terms - Brain-derived neurotrophic factor, diabetic neuropathy, downstream regulatory element antagonist modulator, microglia.