Agonist independent activity of dopamine receptor type 1 (D1R) increases CaV2.2 currents in prefrontal cortex neurons.

CHOU-FREED CAMBRIA; RODRIGUEZ SILVIA S.; MCCARTHY CLARA I.; RAINGO JESICA

Chicago

Congreso; 49th annual meeting of the Society for Neuroscience; 2019

Society for Neuroscience

Dopamine and its receptors play an important yet not fully understood role in the prefrontal cortex (PFC) function. Alterations in dopamine receptor type 1 (D1R) density and sensitivity to dopamine are associated with cognitive deficits of aging and schizophrenia. In pyramidal neurons of the PFC, Kisilevsky and col. (2008) showed that D1R co-localizes and physically interacts with voltage-gated calcium channels type 2.2 (CaV2.2) and that this interaction modulates CaV2.2 density in postsynaptic sites. Furthermore D1R was reported to display constitutive activity through coupling to Gs protein in absence of dopamine, but the impact of this agonist-independent activation of D1R on CaV currents has never been studied. Our aim here is to understand the role of agonist independent D1R activity on the stimulatory effect on CaV2.2 surface expression. To do it we transfected HEK293t cells with increasing D1R:CaV2.2 molar ratios (MR) and verified expression levels using YFP-tagged D1R. We recorded whole-cell calcium currents and found an increase in CaV2.2 current density by D1R co-expression (152.6% of control at 0.1 D1R:CaV2.2 MR, P=0.0029). To explore the role of D1R constitutive activity on this effect, we treated cells with Haloperidol (D1R inverse agonist) and Cholerotoxin (Gs protein inhibitor). Results indicate that the increase in current density depends on D1R constitutive activity. We next aimed to understand the scope of this effect on pyramidal neurons of the PFC, where CaV2.2 has critical post-synaptic functions contributing to firing and plasticity. We recorded voltage gated calcium currents from PFC neurons in brain slices from 4 to 6 week old mice injected with intra-peritoneal haloperidol (1mg/kg) or vehicle, and found that native calcium currents from haloperidol treated mice were significantly smaller than currents from control mice. Moreover we found that the current reduced by haloperidol treatment is mainly CaV2.2 subtype since the sensitivity to ω conotoxin GVIA 1 µM of calcium currents is dramatically reduced in haloperidoI treated mice. In this context, our study could contribute to understand the mechanism involved in cognitive deficits of aging and schizophrenia associated with changes in D1R expression levels at the PFC.