Exposure to female pheromones during pregnancy causes postpartum anxiety in mice

Abstract

The postpartum period is associated with an increased incidence of pathological anxiety, exerting a substantial burden on both the mother and the baby. We have shown that pharmacological suppression of prolactin in early pregnancy decreases maternal neurogenesis to cause postpartum anxiety. The present data demonstrate that physiological suppression of prolactin secretion through exposure to unfamiliar female pheromones throughout pregnancy prevented the normal postpartum attenuation of anxiety in mice, resulting in high anxiety relative to postpartum controls. Female pheromone-exposed mice also showed severely impaired maternal behavior in an anxiogenic situation. Mice exposed to female pheromones had decreased serum prolactin levels in early pregnancy, resulting in an ablation of the normal increase of neurogenesis on day 7 of pregnancy. These data demonstrate that low serum prolactin levels in early pregnancy, whether induced pharmacologically or as a physiological consequence of exposure to unfamiliar female pheromones, result in failure to show the normal adaptive decrease in anxiety after birth. This provides new insight into possible mechanisms that might underlie postpartum anxiety in women.