title: Social stress and CRF-dopamine interactions in the VTA: role in long-term escalation of cocaine self-administration.
abstract: The nature of neuroadaptations in the genesis of escalated cocaine taking remains a topic of considerable interest. Intermittent social defeat stress induces both locomotor and dopaminergic cross-sensitization to cocaine, as well as escalated cocaine self-administration. The current study examines the role of corticotropin releasing factor receptor subtypes 1 and 2 (CRFR1, CRFR2) within the ventral tegmental area (VTA) during social defeat stress. This study investigated whether injecting either a CRFR1 or CRFR2 antagonist directly into the VTA before each social defeat would prevent the development of later (1) locomotor sensitization, (2) dopaminergic sensitization, and (3) escalated cocaine self-administration in rats. CRFR1 antagonist CP376395 (50 or 500 ng/side), CRFR2 antagonist Astressin2-B (100 or 1000 ng/side), or vehicle (aCSF) was microinjected into the VTA 20 min before social defeat stress (or handling) on days 1, 4, 7, and 10. Ten days later, rats were injected with cocaine (10 mg/kg, i.p.) and assessed for either locomotor sensitization, measured by walking activity, or dopaminergic sensitization, measured by extracellular dopamine (DA) in the nucleus accumbens shell (NAcSh) through in vivo microdialysis. Locomotor sensitization testing was followed by intravenous cocaine self-administration. Intra-VTA antagonism of CRFR1, but not CRFR2, inhibited the induction of locomotor cross-sensitization to cocaine, whereas both prevented dopaminergic cross-sensitization and escalated cocaine self-administration during a 24 h "binge." This may suggest dissociation between locomotor sensitization and cocaine taking. These data also suggest that interactions between CRF and VTA DA neurons projecting to the NAcSh are essential for the development of dopaminergic cross-sensitization to cocaine.
authors.affiliation: Department of Psychology, Tufts University, Medford, Massachusetts 02155, and Departments of Psychiatry, Pharmacology, and Neuroscience, Tufts University School of Medicine, Boston, Massachusetts 02110.
authors.forename: Christopher O
authors.initials: CO
authors.lastname: Boyson
authors.forename: Elizabeth N
authors.initials: EN
authors.lastname: Holly
authors.forename: Akiko
authors.initials: A
authors.lastname: Shimamoto
authors.forename: Lucas
authors.initials: L
authors.lastname: Albrechet-Souza
authors.forename: Lindsay A
authors.initials: LA
authors.lastname: Weiner
authors.forename: Joseph F
authors.initials: JF
authors.lastname: DeBold
authors.forename: Klaus A
authors.initials: KA
authors.lastname: Miczek
mesh_terms: D000631:Aminopyridines / Q000494:pharmacology; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D003042:Cocaine / Q000008:administration & dosage / Q000494:pharmacology*; D019970:Cocaine-Related Disorders / Q000523:psychology*; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology*; D004298:Dopamine / Q000494:pharmacology*; D018765:Dopamine Uptake Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D017551:Microdialysis; D008845:Microinjections; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology; D010446:Peptide Fragments / Q000494:pharmacology; D051381:Rats; D020318:Rats, Long-Evans; D018019:Receptors, Corticotropin-Releasing Hormone / Q000187:drug effects; D012646:Self Administration; D012919:Social Behavior; D012931:Social Environment; D013315:Stress, Psychological / Q000523:psychology*; D015819:Substance Abuse, Intravenous; D017557:Ventral Tegmental Area / Q000187:drug effects*
chemical_list: C529296:(3,6-dimethyl-2-(2,4,6-trimethylphenoxy)pyridin-4-yl)(1-ethylpropyl)amine; D000631:Aminopyridines; D018765:Dopamine Uptake Inhibitors; D010446:Peptide Fragments; D018019:Receptors, Corticotropin-Releasing Hormone; C104416:astressin; D003346:Corticotropin-Releasing Hormone; D003042:Cocaine; D004298:Dopamine