Effects of miR-16 mimics on the pain behavior and the expression of its target gene BDNF in rats with bone cancer pain

Abstract

Objective To investigate the expression of miR-16 in spinal cord and the effects of miR-16 mimics on the pain behavior and the expression of its target gene BDNF during the development and maintenance of bone cancer pain. Methods The bone cancer pain model rats were developed by intra-tibia inoculation of Walker 256 mammary gland cells. Before inoculation and 3, 5, 7, 10, 14 d after inoculation, the samples of spinal cord L4~6 lumbar enlargement were collected to detect the expression of miR-16 using real-time PCR. Mice in group BM and group BN were intrathcal injected of miR-16 mimics and its negative control products on 10 d, 11 d, 12 d after inoculation. Paw withdrawal mechanical threshold (PWMT) was measured using von Frey hair mechanical stimulation. The expression of BDNF was detected using western-blot on 14 d after behavior tests. Results Compared with the base level and the level in group S, the significant decrease of miR-16 expression was observed at 5 d~14 d in group T (5 d (0.91±0.04), 7 d (0.77±0.01), 10 d (0.73±0.03), 14 d (0.42±0.08)) (all P<0.05). Compared with SH group, PWMT was significantly decreased in BC and BP groups at 5 d~14 d(P<0.05), and in group BM at 5 d~10 d(P<0.05). Compared with BP group, PWMT was significantly higher in BM group at 10~12 d(P<0.05). Compared with SH group, the expression of BDNF was significantly increased in BN and BP groups((2.78±0.31), (2.34±0.23)) (all P<0.01). Compared with BP group, the expression of BDNF was significantly decreased in BM group (1.42±0.16) (P<0.01). Conclusion miR-16 is downregulated in spinal cord of bone cancer pain rats, while intrathcal injection of miR-16 mimics can attenuate the pain behaviors in a rat model of bone cancer pain and decrease the expression of BDNF. miR-16 may modulate bone cancer pain through BDNF. Key words: Bone cancer pain; Spinal cord; miR-16; miR-16 mimics; Brain-derived neurotrophic foctor