LAUSR

Purpose Polycystic ovary syndrome (PCOS) is a common heterogeneous endocrine disorder companied with neuroendocrine and metabolic disorders. Gut microbiota has been implicated to play a key role in metabolic diseases and the production of neurotransmitters. Previous studies have reported the alterations in the gut microbiota of PCOS patients and animal models, however, most of the articles did not take the effect of age or diet on gut microbiota into account. The aim of this study was to identify the differential gut microbial species in PCOS patients compared with age and BMI-matched healthy control women. Methods We performed physical examinations and dietary survey in 20 women with PCOS (lean PCOS, PL, n  = 10; overweight PCOS, PO, n  = 10) and 20 healthy control women (lean control, CL, n  = 10; overweight control, CO, n  = 10), and collected the blood on the days 1–3 of the menstrual cycle for the measurement of endocrine and metabolic profiles, and inflammatory factors; and collected the feces in non-menstrual period to investigate the composition of gut microbiota by sequencing the V4 region of the 16S rDNA gene in fecal samples. The correlations between clinical parameters and the differential species were evaluated. Results Dietary analysis showed that the intake of dietary fiber, vitamin D were significantly decreased in PCOS. For the first time, our study found an increase of gamma-aminobutyric acid (GABA)-producing species in PCOS, including Parabacteroides distasonis , Bacteroides fragilis and Escherichia coli , which significantly positively correlated with serum LH levels and LH:FSH ratios. Conclusions GABA-producing bacteria that were increased in PCOS, including Parabacteroides distasonis , Bacteroides fragilis and Escherichia coli, showed positive relationship with serum LH levels and LH:FSH ratios. In conclusion, gut microbial dysbiosis in women with PCOS is associated with neuroendocrine changes, revealing a potential gut–brain axis in PCOS.