The complications of
diabetic polyneuropathy (DN) determines its level of severity. It may occur with distinctive clinical symptoms (painful DN) or appears undetected (painless DN). This study aimed to investigate microglia activation 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 (200-230 g) were randomly assigned into three groups: (1) control, (2) painful DN and (3) painless DN. The rats were induced with diabetes by single
intraperitoneal injection of
streptozotocin (60 mg/kg) whilst control rats received
citrate buffer as a 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. The results demonstrated that painful DN 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, painless DN group demonstrated a significant reduction of
pain behaviour score peripherally and centrally with significant reduction of spinal activated microglia,
BDNF and DREAM
proteins expressions. In conclusions, the spinal microglia activation,
BDNF and DREAM
proteins correlate with the
pain behaviour responses between the variants of DN.