GCG and polycystic ovary syndrome: A recent study revealed that PCOS can be induced by alterations in the gut microbiome via the activation of the nuclear receptor FXR.456 Mechanistically, agmatine produced by B. vulgatus can activate FXR, which in turn prevents L cells from secreting glucagon-like peptide-1 (GLP-1), suggesting that FXR is a possible therapeutic target for the treatment of PCOS.456 Moreover, PPAR is a large nuclear receptor superfamily related to energy metabolism and is thus involved in the progression of PCOS.