Pharmacological modulation of AMPA receptor phosphorylation by dopamine and muscarinic receptor agents in the rat medial prefrontal cortex

摘要

Two key transmitters in the medial prefrontal cortex (mPFC), dopamine and acetylcholine, are believed to interact with each other to modulate local glutamatergic transmission, although molecular mechanisms underlying their crosstalk are poorly understood. Here we investigated effects of pharmacological manipulations of dopamine and muscarinic receptors on phosphorylation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors in the adult rat mPFC in vivo. We found that an agonist selective for Gαs-coupled dopamine D1 receptors, , increased AMPA receptor GluA1 subunit phosphorylation at a protein kinase A-sensitive site (S845), while had no effect on GluA1 phosphorylation at S831. An agonist for Gαi/o-coupled dopamine D2 receptors, quinpirole, also increased S845 but not S831 phosphorylation. When coinjected, the two agonists induced an additive increase in S845 phosphorylation. The D1 receptor antagonist blocked the /quinpirole-stimulated S845 phosphorylation. The D2 antagonist eticlopride also partially blocked S845 responses to /quinpirole. VU0152100, a positive allosteric modulator selective for Gαi/o-coupled muscarinic M4 receptors, reduced the S845 phosphorylation induced by and quinpirole injected alone or together. In contrast, coinjection of subthreshold doses of tropicamide, an M4 antagonist, and facilitated S845 phosphorylation. Additionally, coadministered and quinpirole increased the abundance of mPFC GluA1 at extrasynaptic sites. These data reveal that both D1 and D2 receptors upregulate GluA1 phosphorylation in mPFC neurons probably via a direct and indirect mechanism, respectively. The indirect mechanism involves M4 receptors which generally counteract the effect of dopamine on GluA1 phosphorylation.