title: Stress-induced sensitization to cocaine: actin cytoskeleton remodeling within mesocorticolimbic nuclei.
abstract: This study investigated the consequence of repeated stress on actin cytoskeleton remodeling in the nucleus accumbens (NAc) and prefrontal cortex (Pfc), and the involvement of this remodeling in the expression of stress-induced motor cross-sensitization with cocaine. Wistar rats were restrained daily (2 h) for 7 days and, 3 weeks later, their NAc and Pfc were dissected 45 min after acute saline or cocaine (30 mg/kg i.p.). F-actin, actin-binding proteins (ABP) and GluR1 were quantified by Western blotting, and dendritic spines and postsynaptic density (PSD) size measured by electron microscopy. In the NAc from the stress plus cocaine group we observed a decrease in the phosphorylation of two ABPs, cofilin and cortactin, and an increase in the PSD size and the surface expression of GluR1, consistent with a more highly branched actin cytoskeleton. The Pfc also showed evidence of increased actin polymerization after stress as an increase was observed in Arp2, and in the number of spines. Inhibiting actin cycling and polymerization with latrunculin A into the NAc, but not the Pfc, inhibited the expression of cross-sensitization to cocaine (15 mg/kg i.p.) and restored the expression of GluR1 to control levels. This study shows that a history of repeated stress alters the ability of a subsequent cocaine injection to modulate dendritic spine morphology, actin dynamics and GluR1 expression in the NAc. Furthermore, by regulating GluR1 expression in the NAc, elevated actin cycling contributes to the expression of cross-sensitization between stress and cocaine, while stress-induced changes in the Pfc were not associated with cross-sensitization.
authors.affiliation: IFEC-CONICET, Departamento de Farmacología, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Esparza
authors.forename: Flavia
authors.initials: F
authors.lastname: Bollati
authors.forename: Constanza
authors.initials: C
authors.lastname: Garcia-Keller
authors.forename: Miriam B
authors.initials: MB
authors.lastname: Virgolini
authors.forename: Lidia M
authors.initials: LM
authors.lastname: Lopez
authors.forename: Alicia
authors.initials: A
authors.lastname: Brusco
authors.forename: Hao-Wei
authors.initials: HW
authors.lastname: Shen
authors.forename: Peter W
authors.initials: PW
authors.lastname: Kalivas
authors.forename: Liliana M
authors.initials: LM
authors.lastname: Cancela
mesh_terms: D008841:Actin Cytoskeleton / Q000187:drug effects / Q000378:metabolism*; D051339:Actin Depolymerizing Factors / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D000818:Animals; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D059333:Central Nervous System Sensitization; D003042:Cocaine / Q000494:pharmacology*; D051356:Cortactin / Q000378:metabolism; D049229:Dendritic Spines / Q000378:metabolism / Q000648:ultrastructure; D015870:Gene Expression; D008297:Male; D009043:Motor Activity; D009714:Nucleus Accumbens / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D010766:Phosphorylation; D058105:Polymerization; D057907:Post-Synaptic Density / Q000378:metabolism / Q000648:ultrastructure; D017397:Prefrontal Cortex / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D018091:Receptors, AMPA / Q000235:genetics / Q000378:metabolism; D012149:Restraint, Physical; D013315:Stress, Psychological / Q000378:metabolism / Q000503:physiopathology*; D053778:Thiazolidines / Q000494:pharmacology
chemical_list: D051339:Actin Depolymerizing Factors; D000199:Actins; D019086:Bridged Bicyclo Compounds, Heterocyclic; D051356:Cortactin; D018091:Receptors, AMPA; D053778:Thiazolidines; D003042:Cocaine; C037067:latrunculin A