〔Abstract〕 Objective To explore the expression of the μ-opioid receptor(MOR) and the effects of intracellular vesicle transport on the MOR expression during endomorphin 2(EM2) analgesia. Methods Adult male SD rats were randomly divided into 3 groups: control(naive) group, neuropathic pain group and drug group. Spared nerve injury(SNI) induced neuropathic pain rats were employed as the pain model. The drug group rats were the SNI pain ones intrathecally injected with EM2. The methods of immunofluorescence single staining and Western blot were used to detect the expression of MOR total protein, phosphorylated protein and Rab7 protein. Immunofluorescence double staining was used to detect the expression of MOR/Rab7 and MOR/LAMP1 co-labeled immunoreactivity. Results Compared with the control group, the expression of total MOR protein and phosphorylated protein in the dorsal root ganglion(DRG) of the SNI pain rats decreased(P<0.05), and the expression of Rab7 significantly increased(P<0.05). The expression of MOR/Rab7 co-labeled immunoreactivity in Rab7 and MOR immunoreactive(-ir) products and MOR/LAMP1 co-labeled immunoreactivity in MOR and LAMP1-ir products both increased(P<0.05). Multiple intrathecal injection of EM2 significantly increased paw withdrawal threshold in the SNI neuropathic pain rats(P<0.01), the expression of MOR protein and phosphorylated protein in DRG was increased(P<0.05), while the expression of Rab7 decreased(P<0.05). Compared with the control group, the expression of MOR/Rab7 positive products in Rab7 and MOR positive ones decreased, and the expression of MOR/LAMP1 positive products in LAMP1 and MOR positive markers decreased(P<0.05). Conclusion In the process of analgesia, EM2 inhibits the expression of Rab7 in the DRG of SNI neuropathic pain rats, reduces the transport of MOR to lysosomes, and promotes the re-sensitization of MOR.