Purpose: Although increasing lines of evidence showed associations between serum uric acid (UA) levels and schizophrenia, the causality and the direction of the associations remain uncertain. Thus, we aimed to assess whether the relationships between serum UA levels and schizophrenia are causal and to determine the direction of the association. Patients and Methods: Two-sample bidirectional Mendelian randomization (MR) analyses and various sensitivity analyses were performed utilizing the summary data from genome-wide association studies within the Global Urate Genetics Consortium and the Psychiatric Genomics Consortium. Secondary MR analyses in both directions were conducted within summary data using genetic risk scores (GRSs) as instrumental variables. Results: Three MR methods provided no causal relationship between serum UA and schizophrenia. Furthermore, GRS approach showed similar results in the three MR methods after adjustment for heterogeneity. By contrast, inverse variance weighted method, weighted median and GRS approach suggested a causal effect of schizophrenia risk on serum UA after adjustment for heterogeneity (per 10-symmetric percentage increase in schizophrenia risk, beta: − 0.039, standard error (SE): 0.013, P = 0.003; beta: − 0.036, SE: 0.018, P = 0.043; beta: − 0.039, SE: 0.013, P = 0.002; respectively). Moreover, in both directions’ analyses, the heterogeneity and sensitivity tests suggested no strong evidence of bias due to pleiotropy. Conclusion: Schizophrenia may causally affect serum UA levels, whereas the causal role of serum UA concentrations in schizophrenia was not supported by our MR analyses. These findings suggest that UA may be a useful potential biomarker for monitoring treatment or diagnosis of schizophrenia rather than a therapeutic target for schizophrenia.

Oil tea is a type of traditional tea beverage used for treating various ailments in minority population in Guangxi, China. Our previous study showed oil tea improved glucose and lipid levels in type 2 diabetic mice. Yet, the underling molecular mechanisms are still not understood. This study aimed at assessing the effect of oil tea on glucose homeostasis and elucidating the molecular mechanisms underlying the oil tea-induced antidiabetic effects. Twenty seven db/db mice were gavaged with saline, metformin and oil tea for 8 weeks with measurement of biochemical profiles. A real-time2 (RT2) profiler polymerase chain reaction (PCR) array comprising 84 genes involved in glucose metabolism was measured and validated by quantitative PCR (qPCR). The association between the candidate genes and type 2 diabetes were further analyzed in a case-control study in the Chinese minority population. Oil tea treatment facilitated glucose homeostasis by decreasing fasting blood glucose and total cholesterol, and improving glucose tolerance. Suppressing phosphoenolpyruvate carboxykinase 1 (PCK1) expression was observed in the oil tea treatment group and the expression was significantly correlated with fasting blood glucose levels. Target prediction and functional annotation by WEB-based GEne SeT AnaLysis Toolkit (WebGestalt) revealed that PCK1 mainly involved in the glycolysis/gluconeogenesis pathway among the top Kyoto Encyclopedia of Genes and Genomes (KEGG) database pathways. Both rs707555 and rs2071023 in PCK1 were significantly associated with type 2 diabetes in the minority population of Guangxi. Our findings indicated oil tea improved glucose homeostasis via down-regulation of PCK1 and PCK1 may be a genetic marker for the treatment of type 2 diabetes.