Activation of cyclin-dependent kinase 5 broadens action potentials in human sensory neurons

Abstract

Chronic pain is one of the most devastating and unpleasant conditions, associated with many pathological states. Tissue or nerve injuries induce extensive neurobiological plasticity in nociceptive neurons, which leads to chronic pain. Recent studies suggest that cyclin-dependent kinase 5 (CDK5) in primary afferents is a key neuronal kinase that modulates nociception through phosphorylation under pathological conditions. However, the impact of the CDK5 on nociceptor activity especially in human sensory neurons is not known. To determine the CDK5-mediated regulation of human dorsal root ganglia (hDRG) neuronal properties, we have performed the whole-cell patch clamp recordings in neurons dissociated from hDRG. CDK5 activation induced by overexpression of p35 depolarized the resting membrane potential (RMP) and reduced the rheobase currents as compared to the control neurons. CDK5 activation changed the shape of the action potential (AP) by increasing AP -rise time, -fall time, and -half width. The application of a prostaglandin E2 (PG) and bradykinin (BK) cocktail in control hDRG neurons induced the depolarization of RMP and the reduction of rheobase currents along with increased AP rise time. However, PG and BK applications failed to induce any significant changes in the p35-overexpressing group. We conclude that, in dissociated hDRGs neurons, CDK5 activation through the overexpression of p35 broadens the AP and that CDK5 may play important roles in the modulation of AP properties in human primary afferents under the condition in which CDK5 is upregulated, contributing to chronic pain.

Sensitization of human and rat nociceptors by low dose morphine is toll-like receptor 4-dependent

“…Rheobase, the minimal sustained current required to generate an action potential (AP), was selected for our measure of neuronal excitability as it is a well-defined electrophysiological property that reflects excitability in DRG neurons. 25 , 28 , 33 – 35 Percentage decrease in rheobase was used as the measure of nociceptor sensitization. The effect of 100 nM morphine on rheobase was evaluated in putative C-type nociceptive (small-diameter) neurons from rat (soma diameter <30 µm) 36 – 39 and human (soma diameter 40-60 µm) DRG.…”

Biophysical Essentials – A Full Stack Open-Source Software Framework for Conserved and Advanced Analysis of Patch-Clamp Recordings

“…Integration of our own data with other patch-clamp data sets e.g. from human primary sensory neurons (Tiwari et al, 2023;Zurek et al, 2023) in BPE offers great potential to elucidate functional species dependent differences which are already demonstrated at the RNA and protein level (Ray et al, 2018). To enable build up of comprehensive electrophysiological data sets, data reanalysis and maximum exploitation of already available and new data, an online platform generated within the BPE environment with the community, independent from the patch clamp amplifier system, has In comparison to pure data analysis tools like IgorPro or PatchView, BPE additionally provides interaction with amplifier-and camera hardware thus allowing for process automatization and collection of other data types, such as a image documentation of the recorded cell.…”

Sensitization of Human and Rat Nociceptors by Low Dose Morphine is TLR4-dependent

“…76 ng/mL, corresponding to a single sub-analgesic dose of 0.15 mg/kg) 16,44 on neuronal excitability. Rheobase, the minimal sustained current required to generate an action potential (AP), was selected for our measure of neuronal excitability as it is a well-defined electrophysiological property that reflects excitability in DRG neurons 11,29,30,51,52 . Percentage decrease in rheobase was used as the measure of nociceptor sensitization.…”