Adenosine A1 and dopamine d1 receptor regulation of AMPA receptor phosphorylation and cocaine-seeking behavior.

AMPAR (α-amino-3-hydroxy-5-methylisoxazole-4-propionate glutamate receptor) stimulation in the nucleus accumbens (NAc) is critical in cocaine seeking. Here, we investigate the functional interaction between D1 dopamine receptors (D1DR) and AMPARs in the NAc, and explore how A1 adenosine receptor (A1AR) stimulation may reduce dopamine-induced facilitation of AMPARs and cocaine seeking. All animals were trained to self-administer cocaine and were tested for reinstatement of cocaine seeking following extinction procedures. The role of AMPARs in both AMPA- and D1DR-induced cocaine seeking was assessed using viral-mediated gene transfer to bi-directionally modulate AMPAR activity in the NAc core. The ability of pharmacological AMPAR blockade to modulate D1DR-induced cocaine seeking also was tested. Immunoblotting was used to determine whether stimulating D1DR altered synaptic AMPA GluA1 phosphorylation (pGluA1). Finally, the ability of an A1AR agonist to modulate D1DR-induced cocaine seeking and synaptic GluA1 receptor subunit phosphorylation was explored. Decreasing AMPAR function inhibited both AMPA- and D1DR-induced cocaine seeking. D1DR stimulation increased AMPA pGluA1(S845). Administration of the A1AR agonist alone decreased synaptic GluA1 expression, whereas coadministration of the A1AR agonist inhibited both cocaine- and D1DR-induced cocaine seeking and reversed D1DR-induced AMPA pGluA1(S845). These findings suggest that D1DR stimulation facilitates AMPAR function to initiate cocaine seeking in D1DR-containing direct pathway NAc neurons. A1AR stimulation inhibits both the facilitation of AMPAR function and subsequent cocaine seeking, suggesting that reducing AMPA glutamate neurotransmission in direct pathway neurons may restore inhibitory control and reduce cocaine relapse.