Voluntary physical activity increases maternal care and reduces anxiety- and depression-related behaviours during the postpartum period in mice.

A growing body of evidence suggests voluntary physical activity is associated with decreased stress-related disorders such as anxiety- and depression-like behaviours in both humans and rodents. The postpartum period is also a vulnerable transition time for the development of these neurobehavioural disorders in women. This study aimed to determine whether voluntary physical activity during pregnancy and postpartum period can increase maternal care and decrease anxiety- and depression-related behaviours in postpartum dams. To this end, pregnant mice were exposed to running wheel during their gestational and postpartum periods, and then nest building, active nursing, and licking/grooming behaviours were recorded as maternal care. To assess depression and anxiety-related symptoms, several behavioural tests such as the novelty-suppressed feeding test, tail suspension test, sucrose preference test, social interaction test, forced swim test, open field, elevated plus maze, light-dark box, and elevated zero maze were used. To identify the most important mechanisms behind these behavioural alterations, we measured oxytocin, adrenocorticotropic hormone (ACTH) and corticosterone in the serum and serotonin in the brain of postpartum dams. Our findings showed that running wheel significantly increased maternal care, and decreased depression-like behaviour during the postpartum period through increasing serum oxytocin and brain serotonin levels, whereas it decreased anxiety-like behaviour via attenuating the hypothalamic-pituitaryadrenal (HPA) axis activity by measuring ACTH and corticosterone levels in postpartum dams. Overall, this study suggests that voluntary physical activity during pregnancy and the postpartum period might improve maternal care and decrease anxiety and depression-related behaviours in postpartum dams.