Antipsychotic administration reduces native calcium current sensitivity to a D1/D5R specific agonist in PFC neurons

MCCARTHY C. I.; RAINGO J.; RODRIGUEZ S. S.

San Francisco

Congreso; 2020 Virtual Dopamine Conference; 2020

ViDA Organization Committee

Different physiological and pathological states greatly correlate with changes in D1R density and sensitivity to dopamine in the prefrontal cortex (PFC). While many studies have examined the behavioral effects related to alterations in D1R properties, the downstream cellular events triggered by these changes remain uncertain. A previous report showed that D1R and voltage-gated calcium channel type-2 (CaV2.2) physically interact in layer V/VI pyramidal neurons of the medial PFC. Here, we aimed to understand the underlying mechanisms and functional output of CaV2.2 modulation by D1R. We performed patch-clamp experiments on transfected HEK293T cells and wild-type C57BL/6 mouse brain slices, as well as imaging experiments and cAMP measurements. We previously described that D1R constitutively increases CaV2.2 currents in HEK293T cells and that this effect is prevented by pre-incubation with a D1R inverse agonist, chlorpromazine. Here, we evaluated native calcium currents sensitivity to a battery of D1R-like and D2R-like agonists and antagonists and found a clear predominance of D1R-like receptors in layer V/VI pyramidal neurons of the medial PFC. Next, we performed intraperitoneal injections of the antipsychotic drug and D1R-like inverse agonist, chlorpromazine, and found that this treatment reduced native calcium currents? sensitivity to ω-conotoxin-GVIA and their size by ~49%, indicating a selective effect on CaV2.2. Additionally, we found that reducing D1R-like constitutive activity correlates with a decrease in native calcium currents sensitivity to D1R-like agonist-evoked activation. Our results could be interpreted as a stimulatory effect of D1R constitutive activity on the number of CaV2.2 channels available for dopamine-mediated modulation, thus increasing the sensitivity of calcium currents to dopamine in pyramidal neurons of the medial PFC. To our knowledge, these observations represent the first physiological role reported for D1R constitutive activity.