Objective To investigates the effect of acupuncture on sensitization of Zusanli(ST36)in rats with different functional states by using healthy and knee osteoarthritis model rats.Methods Male SD rats were randomly divided into control,model,model-acupuncture and blank-acupuncture group,with 7 rats in each group.KOA rat model was prepared by intra-articular injection of 1 mg·50 μL-1 monoiodoacetic aci(MIA)in model group and model-acupuncture group.On the second day of modeling,acupuncture treatment was performed on the left Zusanli of the model acupuncture group and the blank-acupuncture group,once everyday for 20 min,5 times as a course of treatment,2 days between courses.The general condition,knee joint diameter,plantar thermal pain threshold and Lequesne MG score of rats was observed before modeling and after acupuncture.Observing the morphology of knee joint cartilage to judge whether the model is successful,measuring the mechanical pain threshold of Zusanli to investigate the acupoint sensitization,observing and counting the morphology of skin mast cells in the acupoint area,and detecting the expression of skin calcitonin gene-related peptide(CGRP)in the acupoint area.Results The mechanical pain threshold of Zusanli after acupuncture in model group and blank-acupuncture group decreased significantly after modeling(P<0.01,P<0.05),compared with the control group,the change rate of mechanical pain threshold in model group and blank-acupuncture group increased significantly(P<0.05),compared with the model group,the mechanical pain threshold of Zusanli in the model-acupuncture group decreased significantly(P<0.01).Compared with the control group,the fluorescence intensity of CGRP protein in the skin tissue of Zusanli in the model group increased significantly(P<0.01),MC degranulation rate increased significantly(P<0.05),and there was no significant difference in the fluorescence intensity of CGRP protein of Zusanli in the blank-acupuncture group(P>0.05),MC degranulation rate increased obviously(P<0.01),CGRP protein of Zusanli in the model-acupuncture group was significantly reduced compared with the model group(P<0.01),and there was no significant difference in the degranulation rate of MC(P>0.05).Conclusion Acupoint sensitization can occur in different functional states of rats.Zusanli(ST36)of KOA model rats can be sensitized,and acupuncture stimulation can make Zusanli sensitization caused by disease disappear.Under physiological conditions,acupuncture stimulation can induce similar sensitization phenomenon.