We have previously demonstrated that the arrhythmic expressions of circadian clock genes due to constant darkness induce glycometabolic and reproductive hallmarks of polycystic ovary syndrome (PCOS) in rats. Limosilactobacillus reuteri (L.reuteri) is a promising dietary intervention for host dysmetabolism, while its potential effect on circadian dysrhythmia-induced PCOS remains elusive. Here, we evaluated the amelioration of L.reuteri regimen on constant darkness-induced PCOS-like rats through detecting hepatic gene expression profiles by RNA-seq. Overall design: The control group was under a circadian rhythm of 12:12 h light-dark cycle (lights on at 7:30 a.m. and off at 7:30 p.m.), orally given with saline once a day. The darkness group and the darkness+L.reuteri group were respectively given with saline or L.reuteri (1010 CFU/ml, 100 mg/d) by daily oral gavage during 8-week constant darkness housing. RNA was isolated from 24 liver samples of 14-week-old female rats from the above 3 groups.