Deletion of the voltage-gated calcium channel gene, Ca _V 1.3, reduces Purkinje cell dendritic complexity without altering cerebellar-mediated eyeblink conditioning

Genetic variation in CACNA1D, the gene that encodes the pore-forming subunit of the L-type calcium channel Ca _V 1.3, has been associated with increased risk for neuropsychiatric disorders that display abnormalities in cerebellar structures. We sought to clarify if deletion of Ca _V 1.3 in mice would induce abnormalities in cerebellar cortex cytoarchitecture or synapse morphology. Since Ca _V 1.3 is highly expressed in cerebellar molecular layer interneurons (MLIs) and L-type channels appear to regulate GABA release from MLIs, we hypothesized that loss of Ca _V 1.3 would alter GABAergic synapses between MLIs and Purkinje cells (PCs) without altering MLI numbers or PC structure. As expected, we did not observe changes in the numbers of MLIs or PCs. Surprisingly, Ca _V 1.3 KO mice do have decreased complexity of PC dendritic arbors without differences in the number or structure of GABAergic synapses onto PCs. Loss of Ca _V 1.3 was not associated with impaired acquisition of delay eyeblink conditioning. Therefore, our data suggest that Ca _V 1.3 expression is important for PC structure but does not affect other measures of cerebellar cortex morphology or cerebellar function as assessed by delay eyeblink conditioning.