title: Mesocortical dopamine depletion and anxiety-related behavior in the rat: sex and hemisphere differences.
abstract: The mesocortical dopamine (DA) system of the rat plays an important role in prefrontal cortex (PFC) regulation of stress and emotion and exhibits functional hemispheric asymmetry for such processing. Since few studies examine sex differences in this context, we compared the effects of left vs. right unilateral PFC DA depletion in males and females in several behavioral situations associated with anxiety or aversion. Adult rats received unilateral injections of 6-hydroxydopamine (6-OHDA) or vehicle in the ventromedial (vm) PFC. Behavioral tests included a predator odor burying test, elevated plus maze and sucrose consumption with simple taste aversion. Tissue analysis confirmed that vmPFCs injected with 6-OHDA were depleted of DA (75-85%) compared to controls. Burying behavior and sucrose consumption were affected only by left lesions, similarly in both sexes. However, risk assessment behaviors were affected by right lesions in opposite directions in males and females. Behaviors modified preferentially by the left cortex thus showed less evidence of sex differences than those modulated by the right. While mesocortical DA depletion effects are lateralized, the nature of these effects can vary with sex and specific behavior. Such findings may be clinically significant, given the large gender differences in the incidence of mood and anxiety disorders, which also show many lateralized prefrontal abnormalities.
authors.affiliation: Department of Psychiatry, McGill University, Montréal, Québec, Canada. Electronic address: ron.sullivan@mcgill.ca.
authors.forename: R M
authors.initials: RM
authors.lastname: Sullivan
authors.affiliation: Department of Psychiatry, McGill University, Montréal, Québec, Canada.
authors.forename: M M
authors.initials: MM
authors.lastname: Dufresne
authors.affiliation: Department of Psychiatry, McGill University, Montréal, Québec, Canada.
authors.forename: D
authors.initials: D
authors.lastname: Siontas
authors.affiliation: Department of Psychiatry, McGill University, Montréal, Québec, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Chehab
authors.affiliation: Department of Psychiatry, McGill University, Montréal, Québec, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Townsend
authors.affiliation: Department of Psychiatry, McGill University, Montréal, Québec, Canada.
authors.forename: F
authors.initials: F
authors.lastname: Laplante
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000097:blood; D000818:Animals; D001007:Anxiety / Q000473:pathology / Q000503:physiopathology*; D019422:Dietary Sucrose / Q000008:administration & dosage; D004298:Dopamine / Q000378:metabolism*; D030762:Estrous Cycle / Q000502:physiology; D005106:Exploratory Behavior / Q000502:physiology; D007839:Functional Laterality / Q000502:physiology*; D018782:Maze Learning / Q000502:physiology; D009043:Motor Activity / Q000502:physiology; D009483:Neuropsychological Tests; D016627:Oxidopamine; D011235:Predatory Behavior; D017397:Prefrontal Cortex / Q000473:pathology / Q000503:physiopathology*; D017207:Rats, Sprague-Dawley; D012149:Restraint, Physical; D012727:Sex Characteristics; D013315:Stress, Psychological / Q000503:physiopathology; D055697:Taste Perception / Q000502:physiology
chemical_list: D019422:Dietary Sucrose; D016627:Oxidopamine; D000324:Adrenocorticotropic Hormone; D004298:Dopamine
keywords: Cerebral lateralization; Depression; Predator odor burying test; Risk assessment; Ventromedial prefrontal cortex