Abstract:

 Objective   To study hyperalgesia formation and its possible mechanisms in rats after inoculation of MADB-106 mammary gland carcinoma cells. Methods   16 female SD rats were randomly divided into 2 groups. MADB-106 mammary gland carcinoma cells were inoculated into the marrow cavity of SD rats′ tibia (the model group, or M Group; 8 rats). The control group (C Group) also had 8 rats. The frequency of spontaneous paw withdrawal was documented and movingevoked pain was   recorded by observing the extent of hind limb claudication when the rats walked. Structural damage of the bone was monitored by X-ray and histological analyses. Expression of GFAP in  spinal astrocytes were investigated with immunofluorescence histochemistry. Results   Growth  of rats was much slower in the M Group than in the C Group , as observed 15 d post-inoculation. The frequency of spontaneous paw withdrawal was much higher in the M Group than in the C Group  8 d postinoculation. The score for moving-evoked pain for the M Group was significantly higher than the C Group 8 d post-inoculation． X-ray of the tibia showed  servere bone destruction in the M Group; this was confirmed by a histological analysis which reavealed that the bone marrow cavity was full of tumor cells and the cortical bone was destroyed． Immunofluorescence histochemistry showed that the spinal astrocytes were activated, with strong GFAP expression. Conclusion   Hyperalgesia in rats was developed two weeks after inoculation with MADB-106 mammary gland carcinoma cells, which is associated with the activation of spinal astrocytes.

Key words: Bone cancer pain； Animal  model； Tibia； Inoculation； Hyperalgesia