The original meaning of pathogenesis refers to the cardinal mechanism of the occurrence, development and change of disease, which has three characteristics: cardinal, dominant and directional. The original pathogenesis of primary osteoporosis includes aging and renal failure, which was determined through ancient Chinese medicine books and modern researches. The basic contradiction and evolutionary law of diseases from the level of original pathogenesis were identified, that contribute to the prevention and treatment of primary osteoporosis with Traditional Chinese Medicine.

ObjectiveTo investigate the changes of endogenous metabolites in serum of ovariectomized rats and the effect of Erxiantang on them based on liquid chromatography-mass spectrometry（LC-MS）. MethodTwenty-four healthy female SD rats were randomly divided into sham-operated group， model group and Erxiantang group（7.5 g·kg^-1）， with 8 rats in each group. Bilateral ovarian tissues were excised in the model and Erxiantang groups， and small pieces of adipose tissues were excised in the abdominal cavity of the sham-operated group bilaterally， and gastric administration was started 2 weeks after surgery， and equal volumes of distilled water were gavaged in the sham-operated and model groups. After 12 weeks of administration， blood was collected from abdominal aorta， and non-targeted metabonomics was performed on rat serum by LC-MS， and orthogonal partial least squares-discriminant analysis（OPLS-DA） was used to screen differential metabolites. Metabolic pathway analysis was performed based on Kyoto Encyclopedia of Genes and Genomes（KEGG）， and the levels of key enzymes of metabolic pathways were verified by enzyme-linked immunosorbent assay（ELISA）. ResultThe results of metabonomics showed that 82 differential metabolites between the model group and the sham-operated group were glycerophospholipids， fatty acyls， steroids and steroid derivatives， of which the most significant difference was glycerophospholipids. At the same time， Erxiantang could call back 65 out of 82 differential metabolites， of which 11 were statistically significant， mainly phosphatidylcholine（PC） and lysophosphatidylcholine（LysoPC） in glycerophospholipids， followed by corticosterone and 11-deoxycortisol in steroids and steroid derivatives. Metabolic pathway analysis showed that the pathways of glycerophospholipid metabolism and steroid hormone biosynthesis in model group were changed， and were recovered after the administration of Erxiantang. ELISA results showed that compared with the sham-operated group， serum levels of cholinephosphate cytidylytransferase（CCT）， secretory phospholipase A2（sPLA2） and lysophosphatidylcholine acyltransferase（LPCAT）， which were the key metabolic enzymes of glycerophospholipid metabolite PC and LysoPC， were significantly decreased in the model group（P<0.05， P<0.01）， and choline phosphotransferase 1（CPT1） levels decreased but the difference was not statistically significant， compared with the model group， the levels of CCT， sPLA2 and CPT1 were significantly increased in Erxiantang group（P<0.01）. In addition， compared with the sham-operated group， the levels of cholesterol（TC）， triglyceride（TG） and low density lipoprotein cholesterol（LDL-C） were significantly increased in the model group（P<0.01）， the high density lipoprotein cholesterol（HDL-C） level was decreased（P<0.05）， compared with the model group， the levels of TC， TG and LDL-C were significantly decreased and the level of HDL-C was significantly increased in Erxiantang group（P<0.01）. ConclusionEndogenous metabolites and related metabolic pathways in ovariectomized rats were altered， and Erxiantang can reverse some of the different metabolites and related pathways， such as regulating glycerophospholipid metabolism by regulating metabolic enzymes CCT， sPLA2 and CPT1 to increase the levels of PC and LysoPC， and then improve the pathological changes such as lipid metabolism disorder in ovariectomized rats.