Effects of Glial Cell Line-Derived Neurotrophic Factor Intrathecal Injection on Spinal Dorsal Horn Glial Fibrillary Acidic Protein Expression in a Rat Model of Neuropathic Pain

Glial fibrillary acidic protein (GFAP) is a specific astrocytic marker in the central nervous system. Few studies on the effects of glial cell line-derived neurotrophic factor (GDNF) intrathecal injection on GFAP expression exist in the literature. The present study determined GFAP expression in rat spinal dorsal horn following a spinal nerve ligation (SNL). The effects of GDNF intrathecal injection on GFAP expression were examined to gather experimental evidence on the mechanisms underlying neuropathic pain. Following L5-6 SNL, male Sprague-Dawley rats were randomly divided into four groups: normal control, sham-operated, SNL, and GDNF. Each group was further divided into three subgroups (n = 10) according to the times of sacrifice: 3, 7, and 14 days after surgery. Compared with the normal control and the sham-operated groups, GFAP expression in the SNL group increased at day 3 after surgery and lasted until 14 days after. GFAP expression was significantly less in the GDNF group compared with the SNL group which lasted until 14 days after surgery, suggesting that rat spinal dorsal horn GFAP expression contributes to SNL-induced neuropathic pain. The mechanisms underlying GDNF alleviation of neuropathic pain were shown to be related to the GDNF inhibition of GFAP expression in the spinal dorsal horn.