ABSTRACT
<p><b>OBJECTIVE</b>To observe the intervention of electroacupuncture (EA) with different current frequencies and treatment frequencies on pain thresholt in rats with bone-cancer pain, so as to optimize treatment parameters of EA against bone cancer pain; and by measuring gene expression of opioid receptor and precursor in different tissues to preliminarily explore the possible mechanism of EA against bone cancer pain.</p><p><b>METHODS</b>Ninety healthy female SD rats were randomly divided into a control group, a model group, EA groups (6 subgroups according to different frequencies) and a sham EA group, ten rats in each one. Rats in the control group were injected with 10 µL of amicrobic phosphate buffer solution (PBS) into tibial cavity; rats in the remaining groups were injected with Walker 256 cancer cells to establish model of bone-cancer pain. No treatment was given to rats in the control group and model group; rats in the EA groups were treated with EA at bilateral "Housanli" (ST 36) and "Genduan" with 3 different current frequencies (2 Hz, 100 Hz and 2 Hz/100 Hz), once a day and once every other day, 30 min per treatment (1mA for 15 min, 2 mA for 15 min); rats in the sham EA group were treated with identical acupoints as the EA group, but the acupoints were needled subcutaneously and EA was connected with power off. All the treatment was given for 14 days. Dynamic plantar aesthesiometer was applied to measure the paw withdrawal thresholds (PWTs) of the affected side before the model establishment, 6d, 8d, 10d, 12d, 14d, 16d, 18d, and 20d after model establishment. The mRNA expressions of µ-opioid receptor (MOR), κ-opioid receptor (KOR), δ-opioid receptor (DOR), proopiomelanocortin (POMC) and prodynorphin (PDYN) in dorsal root ganglion (DRG) and lumbar spinal cord dorsal horn (SCDH) of L4-L6 of the affected side were detected by PCR method.</p><p><b>RESULTS</b>There were no differences in PWTs among all groups before model establishment (P>0. 05). Each time point after model establishment, PWTs in model group were obviously lower than those in the control group (all P<0. 01). Compared with the model group, PWTs in each EA subgroup were all increased (all P<0.05), but the differences at different time points were not significant among EA subgroups (P>0.05). The mRNA expressions of MOR, KOR, POMC, and PDYN in L4-L6 DRG in the 2 Hz/100 Hz II group were significantly higher than those in model group (P<0. 05, P<0. 01), while the mRNA expressions of MOR, KOR, DOR, POMC and PDYN in SCDH were not different compared with the model group (P>0. 05).</p><p><b>CONCLUSION</b>EA treatment has obvious analgesic effect on bone-cancer pain, however, its effect is not related with current frequency and treating frequency. EA against bone-cancer pain may be related with increasing the mRNA expression of some peripheral opioid receptors and precursor.</p>
Subject(s)
Animals , Female , Humans , Rats , Acupuncture Analgesia , Methods , Acupuncture Points , Bone Neoplasms , Electroacupuncture , Methods , Enkephalins , Metabolism , Ganglia, Spinal , Metabolism , Pain , Genetics , Metabolism , Pain Management , Methods , Protein Precursors , Metabolism , Rats, Sprague-Dawley , Receptors, Opioid , Genetics , MetabolismABSTRACT
Objective To observe the functional changes of T lymphocytes in the spleen of rats with bone cancer pain.Methods forty-one healthy female Sprague-Dawley rats were used in this study, and were divided into blank control, PBS and Walker-256 tumor groups.Bone cancer pain model was established by inoculation of Walker 256 cancer cells into the tibial cavity.The paw withdrawal threshold (PWT), paw withdrawal thermal latency (PWL), and spontaneous pain (SP) were all measured before modelling (as base) and at 4, 6, 8, 10, 12, 14, 16, 18, and 20 days after modelling. The function of T lymphocyte proliferation, and the content of T lymphocytes and their subgroups in the spleen were detected by cell counting kit-8 method and flow cytometry, respectively, on day 20 after modelling.Results Before modellng, there were no differences of PWT, PWL, and SP between the PBS and model groups.After modelling, the PWT and SP of model group were significantly decreased on day 4, and were always lower than that of PBS group during the experiment.Statistical analysis revealed that Walker-256 cancer cell inoculation in the tibia induced a significant decrease in PWL on day 8, 10 and 12 after modellng.Compared with the control group, T lymphocyte proliferation, content of T lymphocyte (CD3) and subgroups ( CD4 and CD8) in the PBS group were not significantly decreased.However, T lymphocyte proliferation and the content of CD3 lymphocytes in the model group were significantly lower than those in the blank control group and/or PBS group.Conclusions The bone cancer pain rat model may appear obvious mechanical allodynia and spontaneous pain.Its thermal pain hyperalgesiaonly occurred in the intermediate stage of bone cancer pain. The content of T lymphocytes and its subgroups, and the function of T lymphocyte proliferation are weakened to some extent in the bone cancer pain rat model.