OBJECTIVE  To construct and evaluate a mouse model of Yin-deficiency syndrome induced by overloading forced swimming.

METHODS  The mouse model of Yin-deficiency syndrome was constructed by continuous overload forced swimming. The daily swimming time of model mice gradually increased from 20 min in the first week to 120 min in the sixth week. On the day after the last swim, fresh feces were collected for flora detection. After the anal temperature was measured, the physical changes of mice were detected by weight-bearing swimming, and a small amount of blood was taken from the tail to detect the blood glucose content. The next day, blood was collected from the inner canthus for routine blood testing, and the remaining blood was centrifuged to obtain its plasma. Detected the levels of cAMP, cGMP, ALT, AST, LDH, and BUN in plasma, and perform metabolomics analysis on the remaining plasma. The mice were euthanized after cervical spondylosis, and the thymus, spleen, liver, kidney, and large intestine were weighed and subjected to pathological examination.

RESULTS  Continuous overload swimming had a significant impact on mice, compared with the control group, the model mice showed significant weight loss. In the organ index, the thymus index significantly decreased(P<0.01), the liver index and kidney index significantly increased(P<0.01), and the spleen index significantly increased(P<0.05). After modeling, the blood glucose levels of the model mice decreased significantly compared with the control group(P<0.01), and the anal temperature significantly increased(P<0.05). The results of peripheral blood cell testing showed that compared with the control group, the HCT value of the model mice was significantly increased(P<0.05), LYMPH% was up-regulated(P<0.01), and NEUT% was down-regulated(P<0.01). The activities of ALT, AST, BUN, and cGMP in the plasma of model mice showed no significant differences compared with the control group, while the activities of LDH and cAMP levels significantly increased compared with the control group(P<0.01), resulting in a significant increase in the cAMP/cGMP ratio of the model group(P<0.05). The high-throughput plasma metabolite detection results indicated that there were significant changes in the plasma metabolites of the model mice compared with the control group, with 807 metabolites decreasing and 202 metabolites increasing. Through enrichment analysis, it was found that the model group showed a significant decrease in steroid hormone biosynthesis and linoleic acid metabolism related metabolites. Modeling had a significant impact on the characteristics of mouse fecal microbiota, with a decrease in the abundance of the model group's microbiota and a significant decrease in Shannon, Simpson, and Pielou-e values in Alpha diversity. The results of Beta diversity analysis also showed significant changes, such as a decrease in the abundance of beneficial bacterial groups such as Lactobacillus at the genus level.

CONCLUSION Overloading forced swimming can establish a reliable mouse model of Yin-deficiency syndrome.