RESUMO
<p><b>OBJECTIVE</b>To explore the effects of pre-acupuncture and immediate acupuncture on kidney function and oxygen free radical metabolism in rats with simulated weightlessness.</p><p><b>METHODS</b>Twenty male clean-grade Wister rats were randomly divided into a normal control group, a model group, a pre-acupuncture group and an immediate acupuncture group, 5 rats in each one. The rats in the normal control group did not receive any treatment but free activities for 4 weeks. The rats in the rest groups received 4-week tail suspension to establish the model of simulated weightlessness. One week before the tail suspension, the rats in the pre-acupuncture group were treated with electroacupuncture at "Shenshu" (BL 23), "Pishu" (BL 20) and "Sanyinjiao" (SP 6) for 30 min per treatment, once a day for 7 days. The rats in the immediate acupuncture group received tail suspension and acupuncture at the same time; during the tail suspension, the electroacupuncture was applied at "Shenshu" (BL 23), "Pishu" (BL 20) and "Sanyinjiao" (SP 6) for 30 min per treatment, once every other day for 14 days. The colorimetric method was used to measure the content of blood urea nitrogen (BUN) in serum as well as activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) and content of malonaldehyde (MDA) in renal tissue in each group.</p><p><b>RESULTS</b>Compared with the normal control group, the content of BUN in the model group was increased significantly (P<0.01), the activity of SOD and GSH-PX in nephridial tissue was significantly reduced (both P<0.01), and the content of MDA was increased significantly (P<0.05). Compared with the model group, the content of BUN in the pre-acupuncture group and immediate acupuncture group was significantly reduced (P<0.01, P<0.05), the activity of GSH-PX in the pre-acupuncture group was obviously increased (P<0.05) and the content of MDA in the immediate acupuncture group was increased significantly (P<0.01). Compared with the immediate acupuncture group, the content of MDA in the pre-acupuncture group was lower (P<0.01).</p><p><b>CONCLUSION</b>The pre-acupuncture and immediate acupuncture both have the capacity to improve the kidney function and anti-oxygen free radical injury in rats with simulated weightlessness, however, the capacity to increase the protection ability of the kidney and eliminate free radical in the pre-acupuncture group is superior to that in the immediate acupuncture group, which is likely to be related with improving antioxidant ability of kidney.</p>