Effect of intraperitoneal injection of thalidomide on pain behaviors in a mouse model of bone cancer pain

Abstract

Objective To investigate the effect of intraperitoneal injection of thalidomide on pain behaviors in a mouse model of bone cancer pain. Methods 36 male C3H/HeJ mice were divided randomly into tumor group (n= 18) and sham group (n= 18) ,six mice from each group were chosen to examine the time course of changes in behavior after tumor cells inoculated to the bone. 2 × 105 osteosarcoma NCTC 2472 cells were implanted into the intramedullary space of the right femurs of mice to induce ongoing bone cancer related pain behaviors. The sham group was inoculated by α-MEM without any cells. On the day before inoculation,the tumor mice were divided randomly into tumor + thalidomide group and tumor + vehicle group. The sham group mice were further divided randomly into sham + thalidomide group and sham + vehicle group. Pain ethology indexes such as paw withdrawal mechanical threshold (PWMT) and paw withdrawal thermal latency (PWTL) were observed on 1 d before inoculation and on 3 d ,5 d ,7 d, 10 d, 14 d after inoculation. Results ( 1 ) At day 7 after the operation, compared with sham mice ( 1. 70 ± 0. 33 ) g, PWMT of tumor mice decreased to ( 1.07 ± 0. 30) g (P ＜ 0. 05 ). At day 10, PWTL shortened to ( 12.60 ± 1.69 ) s (P ＜ 0. 05 ) compared with sham mice ( 17.70 ± 1.54 ) s. And the pain behaviors of tumor mice were aggravated along with the development of cancer pain. (2) At day 7 after the operation, compared with tumor + vehicle group ( 1. 07 ± 0.39 ) g, PWMT of tumor + thalidomide group increased to ( 1. 53 ± 0. 39 ) g (P ＜0.05). At day 10, PWTL extended to ( 16.48 ± 1.13 ) s compared with sham mice ( 12.64 ± 1. 56) s (P ＜0. 05 ). Conclusion Intraperitoneal injection of thalidomide can efficiently relieve mechanical hyperalgia and thermal hyperalgia in a mouse model of bone cancer pain. Key words: Thalidomide; Bone cancer pain; Mechanical hyperalgesia; Thermal hyperalgesia