Selective modifications in the nucleus accumbens of dopamine synaptic transmission in rats exposed to chronic stress.
Stressful events are accompanied by modifications in dopaminergic transmission in distinct brain regions. As the activity of the neuronal dopamine (DA) transporter (DAT) is considered to be a critical mechanism for determining the extent of DA receptor activation, we investigated whether a 3-week exposure to unavoidable stress, which produces a reduction in DA output in the nucleus accumbens shell (NAcS) and medial prefrontal cortex (mPFC), would affect DAT density and DA D1 receptor complex activity in the NAcS, mPFC and caudate-putamen (CPu). Rats exposed to unavoidable stress showed a decreased DA output in the NAcS accompanied by a decrease in the number of DAT binding sites, and an increase in the number of DA D1 binding sites and Vmax of SKF 38393-stimulated adenylyl cyclase. In the mPFC, stress exposure produced a decrease in DA output with no modification in DAT binding or in DA D1 receptor complex activity. Moreover, in the CPu stress exposure induced no changes in DA output or in the other neurochemical variables examined. This study shows that exposure to a chronic unavoidable stress that produces a decrease in DA output in frontomesolimbic areas induced several adaptive neurochemical modifications selectively in the nucleus accumbens.
Scheggi
Simona
S
Department of Neuroscience, University of Siena, Siena, Italy.
Leggio
Benedetta
B
Masi
Flavio
F
Grappi
Silvia
S
Gambarana
Carla
C
Nanni
Giulio
G
Rauggi
Riccardo
R
De Montis
Maria Graziella
MG
D000818:Animals; D001552:Benzazepines / Q000493:pharmacokinetics; D001665:Binding Sites / Q000502:physiology; D001667:Binding, Competitive; D002421:Caudate Nucleus / Q000378:metabolism; D002908:Chronic Disease; D004298:Dopamine / Q000378:metabolism*; D050483:Dopamine Plasma Membrane Transport Proteins; D008297:Male; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins / Q000378:metabolism; D009419:Nerve Tissue Proteins; D009714:Nucleus Accumbens / Q000166:cytology / Q000378:metabolism*; D017397:Prefrontal Cortex / Q000378:metabolism; D011699:Putamen / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017447:Receptors, Dopamine D1 / Q000378:metabolism; D013312:Stress, Physiological / Q000378:metabolism*; D009435:Synaptic Transmission / Q000502:physiology*
D001552:Benzazepines; D050483:Dopamine Plasma Membrane Transport Proteins; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D017447:Receptors, Dopamine D1; C493216:Slc6a3 protein, rat; D004298:Dopamine