| Objective To investigate the preventive and therapeutic effects of invigorating spleen recipe, nourishing kidney recipe, and invigorating spleen and nourishing kidney recipe on bone loss in tail-suspended simulated weightlessness rats based on the theory of spleen-kidney correlation, and to reveal its molecular mechanism. Methods Fifty rats were randomly divided into blank control group, tail suspension group, invigorating spleen group, nourishing kidney group, and invigorating spleen and nourishing kidney group, with 10 rats in each group. Except for the blank control group, the rats in other groups were modeled by tail suspension. Rats in each group received corresponding Chinese medicine prescriptions. On the 28th day of the experiment, body weight and the bilateral femurs and tibias of the rats were weighed. Bone mineral density and biomechanical properties of the femurs and tibias were detected. Western blotting method was used to detect the protein expressions of alkaline phosphatase (ALP), secreted protein acidic and rich in cysteine (SPARC), activating transcription factor 4 (ATF4), β-catenin, Dickkopf-1 (DKK1), kringle-containing transmembrane protein 2 (Kremen2), and secreted frizzled-relatedprotein 2 (SFRP2). Results Compared to those in blank control group, biomechanical properties of the femur and tibia in tail suspension group decreased (P<0.05), the ratio of femur and tibia to body weight, bone mineral density, ALP, SPARC, ATF4, β-catenin, and SFRP2 protein expressions significantly decreased, and DKK1 and Kremen2 protein expressions significantly increased in tail suspension group (P<0.01). Compared to those in tail suspension group, the ratio of tibia and femur to body weight, bone mineral density, biomechanical properties, ALP, SPARC, ATF4 protein expressions in tibia of rats increased and Kremen2 protein expression decreased in invigorating spleen group, nourishing kidney group, and invigorating spleen and nourishing kidney group (P<0.05), the expression of β-catenin protein in tibia of rats in invigorating spleen group and nourishing kidney group significantly increased (P<0.01), and the expression of SFRP2 protein significantly increased (P<0.01) and DKK1 significantly decreased (P< 0.01) in nourishing kidney group and invigorating spleen and nourishing kidney group. Compared to those in invigorating spleen and nourishing kidney group, the ratio of tibia and femur to body weight, bone mineral density, biomechanical properties of the femur, and ALP, SPARC, and ATF4 protein expressions in the tibia decreased (P<0.05), the biomechanical properties of the tibia, the expression of β-catenin protein decreased, and the expression of Kremen2 protein increased in the invigorating spleen group, nourishing kidney group, respectively (P<0.05), and SFRP2 protein expression in the tibia of the rats decreased and the expression of DKK1 protein increased in the invigorating spleen group (P<0.05). Conclusion Invigorating spleen recipe, nourishing kidney recipe, and invigorating spleen and nourishing kidney recipe based on the theory of spleen-kidney correlation prevent bone loss caused by tail suspension simulated weightlessness. The effect of invigorating spleen recipe is the best. The mechanism may be related to the activation of classic Wnt signaling pathway. The targets of the three prescriptions on the classic Wnt signaling pathway are slightly different. |