Plasma CORT (μg/dl) (A, B) and ACTH (pg/ml) (C, D) levels across the estrous cycle at basal and stress conditions in E, PF, and C females. For CORT levels, in proestrus, E > C under both basal and stress conditions (*p’s < 0.05). In estrus, E = PF < C under basal conditions (#p’s < 0.05). For ACTH levels, overall (collapse time and phase), E > C (p < 0.05), and E > C (collapse time) in diestrus (p < 0.05).