title: Dopamine and corticotropin-releasing factor synergistically alter basolateral amygdala-to-medial prefrontal cortex synaptic transmission: functional switch after chronic cocaine administration.
abstract: Basolateral amygdala (BLA) neurons provide a major excitatory input to medial prefrontal cortex (mPFC)-layer V pyramidal neurons. Under stressful conditions, commonly associated with chronic cocaine abuse, altered BLA-to-mPFC synaptic transmission could lead to defective emotional information processing and decision making within the mPFC and result in misguided and inappropriate behaviors. We examined the effects of cocaine administered chronically in vivo on EPSCs recorded from a putative BLA-mPFC pathway in vitro and their modulation by dopamine (DA), corticotropin-releasing factor (CRF), and their combination (DA plus CRF). In saline-treated animals, activation of D(1/5) receptors depressed BLA-mPFC EPSCs, whereas CRF1 receptor activation alone had no effect on EPSCs. Activating D(1/5) and CRF1 receptors in combination, however, worked synergistically through presynaptic and postsynaptic mechanisms to depress EPSCs to levels greater than D(1/5) receptor activation alone. After chronic cocaine administration, the function of DA(1/5) and CRF receptors switched from inhibitory to excitatory. In slices from cocaine-treated animals, putative BLA-mPFC EPSCs were depressed through a presynaptic mechanism. Now, activation of either D(1/5) or CRF2 receptors increased the cocaine-induced, depressed EPSCs. Additionally, simultaneous activation of presynaptic D(1/5) and CRF2 receptors led to further enhancement of EPSCs. These data indicate that CRF acting synergistically with DA normally potentiates D(1/5)-induced synaptic depression. However, after chronic cocaine, the combined synergistic actions of DA and CRF switched polarity to enhance facilitation of BLA-mPFC glutamatergic transmission. Also unmasked after acute withdrawal from chronic cocaine are endogenous, tonic-inhibitory D2-like and tonic-facilitatory CRF2 receptor actions. These multiple functional and receptor changes may underlie the altered, possibly aberrant, decision-making process after chronic cocaine.
authors.affiliation: Department of Pharmacology and Toxicology, The University of Texas Medical Branch, Galveston, Texas 77555-1031, USA.
authors.forename: Luis
authors.initials: L
authors.lastname: Orozco-Cabal
authors.forename: Jie
authors.initials: J
authors.lastname: Liu
authors.forename: Sebastian
authors.initials: S
authors.lastname: Pollandt
authors.forename: Kady
authors.initials: K
authors.lastname: Schmidt
authors.forename: Patricia
authors.initials: P
authors.lastname: Shinnick-Gallagher
authors.forename: Joel P
authors.initials: JP
authors.lastname: Gallagher
mesh_terms: D000679:Amygdala / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D001522:Behavior, Animal / Q000187:drug effects; D003042:Cocaine / Q000008:administration & dosage*; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology*; D004298:Dopamine / Q000494:pharmacology*; D015259:Dopamine Agents / Q000494:pharmacology; D018765:Dopamine Uptake Inhibitors / Q000008:administration & dosage*; D004357:Drug Synergism; D004558:Electric Stimulation / Q000379:methods; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000528:radiation effects; D006153:Guanosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D066298:In Vitro Techniques; D053444:Inhibitory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D008297:Male; D008954:Models, Biological; D018408:Patch-Clamp Techniques; D017397:Prefrontal Cortex / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D009435:Synaptic Transmission / Q000187:drug effects*; D013873:Thionucleotides / Q000494:pharmacology
chemical_list: D015259:Dopamine Agents; D018765:Dopamine Uptake Inhibitors; D013873:Thionucleotides; D006153:Guanosine Diphosphate; C023427:guanosine 5'-O-(2-thiodiphosphate); D003346:Corticotropin-Releasing Hormone; D003042:Cocaine; D004298:Dopamine