Changes in expression of spinal endothelin-1 and its receptors in a mouse model of bone cancer pain

Abstract

Objective To evaluate the changes in the expression of spinal endothelin-1(ET-1)and its receptors in a mouse model of bone cancer pain(BCP). Methods Ninety-six healthy male SPF C3H/HeN mice, aged 4-6 weeks, weighing 20-25 g, were divided into 2 groups(n=48 each)using a random number table: sham operation group(group S)and BCP group.BCP was produced by injecting α-MEM 20 μl containing 1×104 cells/μl NCTC 2472 osteosarcoma cells into the distal medullary cavity of the right femur bone.In group S, α-MEM 20 μl was injected into the distal medullary cavity of the right femur bone.Mechanical paw withdrawal threshold(MWT)and the number of spontaneous flinches(NSF)were measured on 1 day before inoculation(T0)and 4, 7, 10, 14 and 21 days after inoculation(T1-5). Twelve mice of each group were randomly sacrificed at T0, 2, 4, 5, and the lumbar enlargement segments of the spinal cord were harvested to detect the expression of ET-1, endothelin type A receptor and endothelin type B receptor protein and mRNA(using Western blot or real-time polymerase chain reaction). Results The MWT was significantly lower and the NSF was higher at T1 in group S and at T1-5 in group BCP than at T0(P<0.05). Compared with group S, the MWT was significantly decreased and the NSF was increased at T2-5, and the expression of ET-1, endothelin type A receptor and endothelin type B receptor protein and mRNA was down-regulated at T2, 4, 5 in group BCP(P<0.05). Conclusion The pathophysiological process of BCP is associated with down-regulating the expression of spinal ET-1 and its receptors in mice. Key words: Receptor, endothelin type A; Receptor, endothelin type B; Receptors, G protein-coupled; Bone neoplasms; Pain; Spinal cord