The role of brain-derived neurotrophic factor in pain facilitation and spinal mechanism in rat model of bone cancer pain

Abstract

To investigate the role of brain-derived neurotrophic factor (BDNF) in pain facilitation and spinal mechanisms in the rat model of bone cancer pain. The bone cancer pain model was developed by inoculated Walker 256 mammary gland carcinoma cells into the tibia medullary cavity. Sixty SD female rats were divided into 5 groups (n = 12 each) randomly; group I: control group (sham operation); group II: model group; group III: control group + anti-BDNF intrathecal (i.t.); group IV: model group + control IgG i.t.; group V: model group + anti-BDNF i.t.. Anti-BDNF or control IgG was injected i.t. during 7 to 9th day. Von-Frey threshold was measured one day before operation and every 2 days after operation. On the 9th day after threshold tested, rats were sacrificed after i.t. injection of either anti-BDNF or control IgG, the lumbar 4-6 spinal cord was removed. The expression of the spinal BDNF and the phosphorylation of extracellular signal-regulated protein kinase 1/2 (p-ERK1/2) were detected by immunohistochemistry assay and Western-Blot. Co-expression pattern of BDNF and p-ERK1/2 were determined by double-labeling immunofluorescence. We demonstrated the coexistence of BDNF and p-ERK1/2 in the spinal cord of rats. From the 7 to 9th day after operation, von-Frey threshold in groups II and IV was significantly lower than that in group I and group V (P < 0.01), group V was remarkly higher than that in group IV (P < 0.01). The spinal BDNF and p-ERK1/2 expression in group II or IV were significantly increased compared with that in group I or V (P < 0.01), intrathecal anti-BDNF was significantly suppressed BDNF and p-ERK1/2 expression (P < 0.01). BDNF and p-ERK1/2 was coexistence in the spinal cord of rats, and it maybe involved in the bone cancer pain.