Acceleration of irregular estrous cycle in forced running by midbrain raphe lesions in female rats

► Forced running in a wheel induces irregular estrous cycle and stops ovulating in rats. ► High incidence of irregular estrous cycle is induced by midbrain raphe nucleus lesions. ► Lesions in dorsal and medial raphe nuclei accelerate onset of irregular estrous cycle. ► The midbrain raphe nuclei prevents disturbance of estrous cycle by stress condition.