Cav3.2 T-type calcium channels shape electrical firing in mouse Lamina II neurons

Abstract

The T-type calcium channel, Cav3.2, is necessary for acute pain perception, as well as mechanical and cold allodynia in mice. Being found throughout sensory pathways, from excitatory primary afferent neurons up to pain matrix structures, it is a promising target for analgesics. In our study, Cav3.2 was detected in ~60% of the lamina II (LII) neurons of the spinal cord, a site for integration of sensory processing. It was co-expressed with Tlx3 and Pax2, markers of excitatory and inhibitory interneurons, as well as nNOS, calretinin, calbindin, PKCγ and not parvalbumin. Non-selective T-type channel blockers slowed the inhibitory but not the excitatory transmission in LII neurons. Furthermore, T-type channel blockers modified the intrinsic properties of LII neurons, abolishing low-threshold activated currents, rebound depolarizations, and blunting excitability. The recording of Cav3.2-positive LII neurons, after intraspinal injection of AAV-DJ-Cav3.2-mcherry, showed that their intrinsic properties resembled those of the global population. However, Cav3.2 ablation in the dorsal horn of Cav3.2 GFP-Flox KI mice after intraspinal injection of AAV-DJ-Cav3.2-Cre-IRES-mcherry, had drastic effects. Indeed, it (1) blunted the likelihood of transient firing patterns; (2) blunted the likelihood and the amplitude of rebound depolarizations, (3) eliminated action potential pairing, and (4) remodeled the kinetics of the action potentials. In contrast, the properties of Cav3.2-positive neurons were only marginally modified in Cav3.1 knockout mice. Overall, in addition to their previously established roles in the superficial spinal cord and in primary afferent neurons, Cav3.2 channel appear to be necessary for specific, significant and multiple controls of LII neuron excitability.

Sensory neuropathy and nociception in rodent models of Parkinson's disease

“…Cytosolic calcium overload causes mitochondrial oxidative stress (Dryanovski et al, 2013) and subsequent redox modification of ATP-sensitive potassium channels (K-ATP) (Knowlton et al, 2018) that control the spontaneous tonic pacemaker activity (Liss et al, 2001, 2005; Schiemann et al, 2012), which may lead into a vicious cycle. Although nociceptive neurons are not spontaneously active, L-, N- and T-type voltage-gated calcium channels and K-ATP essentially contribute to the enhancement (calcium channels) (Alles et al, 2018; Candelas et al, 2019; Choi et al, 2016; Neugebauer et al, 1996) or lowering (K-ATP) of nociceptive neuron excitability (Kawano et al, 2009; Rodrigues and Duarte, 2000).…”

Cerebellar dopamine D2 receptors regulate preference for social novelty

“…For AAVDJ-PCp2-Cre production we followed the protocol previously described 76 . The AAV plasmid with Pcp2 (Ple155) minipromoter driving expression of iCre was used (pEMS1986, plasmid #49117.…”

Fast A-type currents shape a rapidly adapting form of delayed short latency firing of excitatory superficial dorsal horn neurons that express the NPY Y1 receptor

“…Voltage-clamp recordings provide additional information about ion channels underlying specific neural activity and have been used to further refine this firing pattern-based classification of dorsal horn neurons (Ruscheweyh & Sandkühler, 2002; Ruscheweyh et al ., 2004; Yasaka et al ., 2010; Smith et al ., 2015), leading to a better understanding of neuronal plasticity after injury, and guiding the development of novel therapeutic targets for chronic pain (Ashcroft, 2000). Examples include electrophysiological studies promoting Cav3.2 channels (Candelas et al ., 2019) and channels mediating I h currents (Tsantoulas et al ., 2017) as targets for pain therapeutics.…”