title: Motivated behavior and the estrous cycle in rats.
mesh_terms: D000818:Animals; D002940:Circadian Rhythm; D004971:Estrus; D005260:Female; D009042:Motivation; D009043:Motor Activity; D011247:Pregnancy; D051381:Rats; D012653:Self Stimulation; D012726:Sexual Behavior, Animal; D013378:Substantia Nigra / Q000502:physiology