APLN and polycystic ovary syndrome: Compared to the control group (83.85 ± 22.65 μmol/L, 190.88 ± 16.44 ng/L, and 24.63 ± 4.59 ng/L, respectively), NO, apelin, and noradrenaline concentrations were significantly higher in patients with PCOS (104.35 ± 44.96 μmol/L, 379.57 ± 40.11 ng/L, and 27.48 ± 5.36 ng/L, respectively) (p < 0.01).