Impact of Pulsed Radiofrequency on Activated Dorsal Root Ganglion Neuronal Dynamics

Abstract

Background: Chronic pain is associated with sustained activation of dorsal root ganglion (DRG) neurons, contributing to pain signal transmission. Objectives: This study investigates the effects of pulsed radiofrequency (PRF) at 2 Hz and 4 Hz on calcium dynamics, mitochondrial membrane potential (MMP), and phosphorylated extracellular signal-regulated kinase (pERK) levels in N-methyl D-Aspartate (NMDA)-activated DRG neurons. Methods: An in vitro experimental study was conducted on seven groups with three replications each, including control, activated model (receiving NMDA 80 µM), Ketamine 100 µM, PRF 2 Hz, PRF 4 Hz, NMDA + PRF 2 Hz, and NMDA + PRF 4 Hz. Cytosolic calcium dynamics were analyzed using confocal laser scanning microscopy. Mitochondrial membrane potential changes and neuronal activity were assessed using an immunocytochemistry assay. Neuronal activity was analyzed by measuring pERK. Data were analyzed using one-way ANOVA and post hoc Tukey HSD (α = 0.05, confidence interval 95%). Results: Exposure to 2 Hz PRF in activated neurons showed more stability than 4 Hz. Mitochondrial membrane potential was significantly elevated in activated neurons (109.60 ± 7.82, 95% CI: 100.75, 118.45) compared to controls (77.64 ± 5.13, 95% CI: 71.83, 83.45, P = 0.000). Both 2 and 4 Hz PRF decreased MMP in activated neurons compared to activated neurons alone. Activated neurons also demonstrated elevated pERK levels (94.80 ± 2.62, 95% CI: 91.84, 97.76) compared to controls (43.37 ± 4.07, 95% CI: 38.76, 47.98, P = 0.000). The PRF at 2 Hz significantly decreased pERK levels in activated neurons (41.27 ± 5.06, 95% CI: 35.54, 46.99, P = 0.000), while 4 Hz PRF showed no significant reduction. Conclusions: Pulsed radiofrequency at 2 Hz normalizes neuronal activity in activated DRG neurons, while 4 Hz does not. Both frequencies increase cytosolic calcium and reduce MMP.