The mesolimbic dopaminergic response to novel palatable food consumption increases dopamine-D1 receptor-mediated signalling with complex modifications of the DARPP-32 phosphorylation pattern.
Acute cocaine administration increases extraneuronal dopamine and Thr34 phosphorylation of dopamine- and cAMP-regulated phosphoprotein (M(r) 32 kDa; DARPP-32) in striatal and cortical areas. Novel palatable food consumption increases extraneuronal dopamine in the same areas. We examined the DARPP-32 phosphorylation pattern in food non-deprived rats at different times after vanilla sugar consumption. The phosphorylation state of DARPP-32 and two cAMP-dependent protein kinase (PKA) substrates, GluR1 and NR1, were detected by immunoblotting. Thirty to 45 min after vanilla sugar consumption, phospho-Thr34 DARPP-32, GluR1 and NR1 levels increased in the nucleus accumbens, and phospho-Thr75 DARPP-32 levels decreased. At 60 min, all parameters returned to baseline values. However, 2 and 3 h after vanilla sugar consumption, phospho-Thr34 DARPP-32 levels decreased, while phospho-Thr75 DARPP-32 levels increased. In contrast to the pattern observed in the NAcS, no delayed changes in DARPP-32 phosphorylation were observed in the mPFC. Both early and delayed DARPP-32, GluR1 and NR1 phosphorylation changes were prevented by a dopamine D1 receptor antagonist administration. The delayed modifications in nucleus accumbens DARPP-32 phosphorylation were prevented by an mGluR5 antagonist administration. The mesolimbic dopaminergic response to an unfamiliar taste is correlated to a gustatory memory trace development, and the observed changes in DARPP-32 phosphorylation may be part of this process.
Rauggi
Riccardo
R
Department of Neuroscience, Pharmacology Unit, University of Siena, Siena, Italy.
Scheggi
Simona
S
Cassanelli
Anna
A
De Montis
Maria Graziella
MG
Tagliamonte
Alessandro
A
Gambarana
Carla
C
D000818:Animals; D001552:Benzazepines / Q000494:pharmacology; D004298:Dopamine / Q000378:metabolism; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; D004435:Eating / Q000187:drug effects / Q000502:physiology*; D008032:Limbic System / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008636:Mesencephalon / Q000187:drug effects / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D017447:Receptors, Dopamine D1 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D031669:Vanilla
D001552:Benzazepines; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; D009419:Nerve Tissue Proteins; D010750:Phosphoproteins; D017447:Receptors, Dopamine D1; D004298:Dopamine