Mechanisms of electroacupuncture at Foot Shaoyang meridian acupoints on inflammatory response in postmenopausal osteoporosis rats based on the PI3K/AKT signaling pathway

ObjectiveTo investigate the effect of electroacupuncture （EA） at Foot Shaoyang meridian acupoints on the inflammatory response in postmenopausal osteoporosis rats by regulating the phosphatidylinositol 3-kinase （PI3K）/protein kinase B （AKT） signaling pathway.MethodsForty Sprague-Dawley （SD） rats were randomly divided into a sham operation group （n=10）， and the remaining rats underwent bilateral ovariectomy to establish a postmenopausal osteoporosis model after 3 months. The model rats were further randomized into a model group， an EA group， and an EA + inhibitor group （n=10）. Rats of The EA group received EA at bilateral “Huantiao” （GB30）， “Yanglingquan” （GB34） （dense-sparse wave， 2 Hz/15 Hz， 0.2—0.6 mA）， and acupuncture at “Xuanzhong” （GB39）， 10 min each time， 5 times a week for 8 weeks， with alternate left-right acupoints. Rats of the EA + inhibitor group received intraperitoneal injection of the PI3K inhibitor LY294002 （10 mg/kg） twice a week for 8 weeks based on the EA treatment. Micro-CT was used to detect the microstructural and morphometric indices of the femoral bone tissue， including bone mineral density （BMD）， bone volume fraction （BV/TV）， trabecular number （Tb.N）， and trabecular separation （Tb.Sp）. HE staining was performed to observe the pathological morphology of the femoral tissue， and tartrate-resistant acid phosphatase （TRAP） staining was used to observe the number of osteoclasts. Immunohistochemical staining was employed to detect the expressions of osteogenic markers Runt-related transcription factor 2 （Runx2）， osteocalcin （OCN）， and type I collagen （Collagen I）. The contents of serum interleukin-1β （IL-1β）， interleukin-6 （IL-6）， and tumor necrosis factor-α （TNF-α）， as well as their mRNA expressions in bone tissue， were detected by ELISA and real-time fluorescent quantitative PCR， respectively. Western blot was used to detect the protein expressions of the PI3K/AKT pathway in femoral tissue.ResultsIn the model group， bone trabeculae were significantly thinned， sparsely and disorderly arranged， the bone marrow cavity was expanded， and the number of osteoclasts was significantly increased； the EA group showed improved bone trabecular structure and reduced osteoclast number. Compared with the sham operation group， the model group had significantly lower BMD， BV/TV， Tb.N， positive expressions of Runx2， OCN， and Collagen I in bone tissue， and ratios of p-PI3K/PI3K and p-AKT/AKT protein expression （PPPPPPPConclusionEA at Foot Shaoyang meridian acupoints can alleviate inflammatory responses and bone loss in postmenopausal osteoporosis rats， and its mechanism may be related to the activation of the PI3K/AKT pathway.