Effect of estrogen on expressions of c-Fos and substance P in dorsal horn of spinal cord in mice following formalin stimulation / 第三军医大学学报

ABSTRACT

Objective To investigate the effect of estrogen on the pain score,c-Fos and substance P expressions in the dorsal horn of the spinal cord in the mice following formalin stimulation.Methods Fifteen C57/BL6 mice were randomized to 3 groups control group(intact mice without estrogen treatment),OVX+V group(ovariectomized mice given vehicle) and OVX+E group(ovariectomized mice with subcutaneous injection of 2 ?g/d 17?-estradiol for 10 d).Pain score was used to assay the role of estrogen in affecting pain threshold in the mice following formalin injected into the right hind paw,and expressions of c-Fos and substance P in the dorsal horn of spinal cord(L3 to L5) in 2 h after injection of formalin was tested with immunohistochemisty to evaluate neuron activity and pain afferent fibers.Results Pain score was increased in ovariectomized mice following formalin stimulation,which was inhibited by estrogen especially in the early stage of secondary phase.The number of c-Fos-like immunoreactivity neuron(FLIN,P