Constant light exposure alters gut microbiota and short‐/medium‐chain fatty acids and aggravates PCOS‐like traits in HFD‐fed rats

Abstract Objective This study investigated the effects of constant light exposure on polycystic ovary syndrome (PCOS)‐like endocrine and metabolic changes in high‐fat diet (HFD)‐fed rats and to elucidate the related microbiotic mechanisms. Methods A total of 32 female Sprague‐Dawley rats were divided into four groups ( n = 8 each): rats on a normal chow diet with standard light‐dark cycle, rats on a normal chow diet with constant light exposure, rats on an HFD with standard light‐dark cycle, and rats on an HFD with constant light exposure. After 16 weeks of treatment, changes in anthropometric parameters, estrous cycle, hormone profiles, ovarian pathology, and gut microbiota and short‐/medium‐chain fatty acids in colon contents were assessed. Results Constant light exposure aggravated PCOS‐like phenotypes in HFD‐fed rats, such as hyperandrogenism, disrupted estrous cycle, and polycystic ovaries. Additionally, constant light exposure and an HFD synergized to decrease α‐diversity of gut microbiota, create a reduced abundance of Ruminococcus genus, and create an increased abundance of Firmicutes and the Firmicutes/Bacteroidetes ratio. In HFD‐fed rats, the group with constant light exposure had an increase in propionate acid and a decrease in total medium‐chain fatty acids in colon contents compared with the standard light‐dark cycle group. Conclusions Constant light exposure causes gut dysbiosis, alters production of short‐ and medium‐chain fatty acids, and aggravates PCOS‐like traits in HFD‐fed rats.