title: Chronic stress alters the dendritic morphology of callosal neurons and the acute glutamate stress response in the rat medial prefrontal cortex.
abstract: We have previously reported that interhemispheric regulation of medial prefrontal cortex (PFC)-mediated stress responses is subserved by glutamate (GLU)- containing callosal neurons. Evidence of chronic stress-induced dendritic and spine atrophy among PFC pyramidal neurons led us to examine how chronic restraint stress (CRS) might alter the apical dendritic morphology of callosal neurons and the acute GLU stress responses in the left versus right PFC. Morphometric analyses of retrogradely labeled, dye-filled PFC callosal neurons revealed hemisphere-specific CRS-induced dendritic retraction; whereas significant dendritic atrophy occurred primarily within the distal arbor of left PFC neurons, it was observed within both the proximal and distal arbor of right PFC neurons. Overall, CRS also significantly reduced spine densities in both hemispheres with the greatest loss occurring among left PFC neurons, mostly at the distal extent of the arbor. While much of the overall decrease in dendritic spine density was accounted by the loss of thin spines, the density of mushroom-shaped spines, despite being fewer in number, was halved. Using microdialysis we found that, compared to controls, basal PFC GLU levels were significantly reduced in both hemispheres of CRS animals and that their GLU response to 30 min of tail-pinch stress was significantly prolonged in the left, but not the right PFC. Together, these findings show that a history of chronic stress alters the dendritic morphology and spine density of PFC callosal neurons and suggest a mechanism by which this might disrupt the interhemispheric regulation of PFC-mediated responses to subsequent stressors.
authors.affiliation: a Department of Psychiatry , Douglas Hospital Research Centre, McGill University , Montréal, Québec , Canada.
authors.forename: Pauline
authors.initials: P
authors.lastname: Luczynski
authors.affiliation: a Department of Psychiatry , Douglas Hospital Research Centre, McGill University , Montréal, Québec , Canada.
authors.forename: Luc
authors.initials: L
authors.lastname: Moquin
authors.affiliation: a Department of Psychiatry , Douglas Hospital Research Centre, McGill University , Montréal, Québec , Canada.
authors.forename: Alain
authors.initials: A
authors.lastname: Gratton
mesh_terms: D000818:Animals; D048430:Cell Shape / Q000502:physiology; D003337:Corpus Callosum / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D003712:Dendrites / Q000378:metabolism / Q000473:pathology*; D049229:Dendritic Spines / Q000378:metabolism / Q000473:pathology; D018698:Glutamic Acid / Q000378:metabolism*; D008297:Male; D009474:Neurons / Q000378:metabolism / Q000473:pathology*; D051381:Rats; D020318:Rats, Long-Evans; D012149:Restraint, Physical; D013312:Stress, Physiological / Q000502:physiology*; D013315:Stress, Psychological / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology
chemical_list: D018698:Glutamic Acid
keywords: Interhemispheric processes; atrophy; dendritic spines; infralimbic cortex; lateralization; neural plasticity; prelimbic cortex