CONICET | Buscador de Institutos y Recursos Humanos

Background and purpose: CaV 3.1-3 currents differentially contribute to neuronal firing patterns. CaV 3 are regulated by G protein-coupled receptors (GPCRs) activity, but information about CaV 3 as targets of the constitutive activity of GPCRs is scarce. Our aim is to investigate the impact of D5R constitutive activity, a GPCR with high levels of basal activity, on CaV 3 functionality. D5R and CaV 3 are expressed in the hippocampus and both have been independently linked to pathophysiological states associated with epilepsy.Experimental approach: our study models were HEK293T cells heterologously expressing D1R or D5R and CaV 3.1-3, and mouse brain slices containing the hippocampus. We used chlorpromazine (CPZ, D1R/D5R inverse agonist) and a D5R mutant lacking constitutive activity as experimental tools. We measured CaV 3 currents and excitability parameters using the patch-clamp technique. We completed our study with computational modeling and imaging technique.Key results: we found a higher sensitivity to TTA-P2 (CaV 3 blocker) in CA1 pyramidal neurons obtained from CPZ-treated animals compared to vehicle-treated animals. We found that CaV 3.2 and CaV 3.3 -but not CaV 3.1- are targets of D5R constitutive activity in HEK293T cells. Finally, we found an increased firing rate in CA1 pyramidal neurons from CPZ-treated animals in comparison with vehicle-treated animals. Similar changes in firing rate were observed on a neuronal model with controlled CaV 3 currents levels.Conclusions and implications: native hippocampal CaV 3 and recombinant CaV 3.2-3 are sensitive to D5R constitutive activity. Manipulation of D5R constitutive activity could be a valuable strategy to control neuronal excitability, especially in exacerbated conditions such as epilepsy.