Background Seasonal breeding in mammals has been widely recognized to be regulated by photoperiod, but the association of gut microbiota with photoperiodic regulation of seasonal breeding has never been investigated. Results In this study, we investigated the association of gut microbiota with photoperiod-induced reproduction in male Brandt’s voles (Lasiopodomys brandtii) through a long-day and short-day photoperiod manipulation experiment and fecal microbiota transplantation (FMT) experiment. We found photoperiod significantly altered reproductive hormone and gene expression levels, and gut microbiota of voles. Specific gut microbes were significantly associated with the reproductive hormones and genes of voles during photoperiod acclimation. Transplantation of gut microbes into recipient voles induced similar changes in three hormones (melatonin, follicle-stimulating hormone, and luteinizing hormone) and three genes (hypothalamic Kiss-1, testicular Dio3, and Dio2/Dio3 ratio) to those in long-day and short-day photoperiod donor voles and altered circadian rhythm peaks of recipient voles. Conclusions Our study firstly revealed the association of gut microbiota with photoperiodic regulation of seasonal breeding through the HPG axis, melatonin, and Kisspeptin/GPR54 system. Our results may have significant implications for pest control, livestock animal breeding, and human health management.

Humans and animals frequently encounter high‐density crowding stress, which may accelerate their aging processes; however, the roles of gut microbiota in the regulation of aging‐related processes under high‐density crowding stress remain unclear. In the present study, it is found that high housing density remarkably increases the stress hormone (corticosterone), accelerates aging‐related processes as indicated by telomere length (in brain and liver cells) and DNA damage or inflammation (as revealed by tumor necrosis factor‐α and interleukin‐10 levels), and reduces the lifespan of Brandt's vole (Lasiopodomys brandtii). Fecal microbiota transplantation from donor voles of habitats with different housing densities induces similar changes in aging‐related processes in recipient voles. The elimination of high housing density or butyric acid administration delays the appearance of aging‐related markers in the brain and liver cells of voles housed at high‐density. This study suggests that gut microorganisms may play a significant role in regulating the density‐dependent aging‐related processes and subsequent population dynamics of animals, and can be used as potential targets for alleviating stress‐related aging in humans exposed to high‐density crowding stress.