Journal
NEUROCHEMISTRY INTERNATIONAL
Volume 122, Issue -, Pages 8-18Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.neuint.2018.10.008
Keywords
Dopamine; Adenosine; Striatum; Medium spiny neuron; PKA; Rap1gap
Categories
Funding
- MEXT
- AMED
- JSPS KAKENHI [17J10615, 17H01380, 17H02220, 15K06772, 17K19483, 16K18393]
- MEXT KAKENHI [17H05561]
- National Institutes of Natural Sciences [01111706]
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Medium spiny neurons (MSNs) expressing dopamine D1 receptor (D1R) or D2 receptor (D2R) are major components of the striatum. Stimulation of D1R activates protein kinase A (PKA) through G(olf) to increase neuronal activity, while D2R stimulation inhibits PKA through G(i). Adenosine A2A receptor (A2AR) coupled to G(off) is highly expressed in D2R-MSNs within the striatum. However, how dopamine and adenosine co-operatively regulate PKA activity remains largely unknown. Here, we measured Raplgap serine 563 phosphorylation to monitor PICA activity and examined dopamine and adenosine signals in MSNs. We found that a D1R agonist increased Raplgap phosphorylation in striatal slices and in D1R-MSNs in vivo. A2AR agonist CGS21680 increased Rap1gap phosphorylation, and pretreatment with the D2R agonist quinpirole blocked this effect in striatal slices. D2R antagonist eticlopride increased Raplgap phosphorylation in D2R-MSNs in vivo, and the effect of eticlopride was blocked by the pretreatment with the A2AR antagonist SCH58261. These results suggest that adenosine positively regulates PKA in D2R-MSNs through A2AR, while this effect is blocked by basal dopamine in vivo. Incorporating computational model analysis, we propose that the shift from D1R-MSNs to D2R-MSNs or vice versa appears to depend predominantly on a change in dopamine concentration.
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