title: Corticosterone treatment impairs auditory fear learning and the dendritic morphology of the rat inferior colliculus.
abstract: Stress leads to secretion of the adrenal steroid hormone corticosterone (CORT). The aim of this study was to determine the effects of chronic CORT administration on auditory and visual fear conditioning. Male Sprague-Dawley rats received CORT (400 mg/ml) in their drinking water for 10 consecutive days; this treatment induces stress levels of serum CORT. CORT impaired fear conditioning (F((1,28)) = 11.52, p < 0.01) and extinction (F((1,28)) = 4.86, p < 0.05) of auditory fear learning, but did not affect visual fear conditioning. In addition, we analyzed the CORT effects on the neuronal morphology of the inferior colliculus (flat neurons, auditory mesencephalon, a key brain area for auditory processing) and superior colliculus (wide-field neurons, related to visual processing) by Golgi stain. CORT decreased dendritic arborization of inferior colliculus neurons by approximately 50%, but did not affect superior colliculus neurons. Thus, CORT had more deleterious effects on the auditory fear processing than the visual system in the brain.
authors.affiliation: Laboratory of Behavioral Neurobiology, Center for Neurobiology and Brain Plasticity, Department of Physiology, Faculty of Sciences, Universidad de Valparaíso, Valparaíso, Chile. alexies.dagnino@uv.cl
authors.forename: Alexies
authors.initials: A
authors.lastname: Dagnino-Subiabre
authors.forename: Miguel Ángel
authors.initials: MÁ
authors.lastname: Pérez
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Terreros
authors.forename: Michelle Y
authors.initials: MY
authors.lastname: Cheng
authors.forename: Patrick
authors.initials: P
authors.lastname: House
authors.forename: Robert
authors.initials: R
authors.lastname: Sapolsky
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D003213:Conditioning, Psychological / Q000187:drug effects / Q000502:physiology; D003345:Corticosterone / Q000097:blood / Q000494:pharmacology*; D003712:Dendrites / Q000187:drug effects / Q000502:physiology; D005239:Fear / Q000187:drug effects / Q000502:physiology; D007245:Inferior Colliculi / Q000033:anatomy & histology / Q000187:drug effects* / Q000502:physiology*; D008297:Male; D018782:Maze Learning / Q000187:drug effects / Q000502:physiology; D008959:Models, Neurological; D010775:Photic Stimulation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013312:Stress, Physiological
chemical_list: D003345:Corticosterone