Pulsed Radiofrequency Effects on the Lumbar Dorsal Root Ganglion of the Domestic Porcine : Pilot Study

Abstract

Introduction. Pulsed radiofrequency (PRF) is a percutaneous minimal invasive procedure for chronic pain management that can be used when conservative treatment methods have been ineffective. The effectiveness of PRF was demonstrated in various good quality randomized control studies, but mechanisms of action are still unclear. Aim of the Study. The aim of our study is to analyse the histological effects of PRF on the domestic porcine dorsal root ganglion (DRG), and evaluate the expression of biomarkers in gangliocytes of the subject(s). Materials and Methods. A total 3 domestic porcines were investigated. Under general anaesthesia and X-ray control, DRG PRF was performed. Four lumbar DRGs (L1, L2, L3, L4) were randomly treated. The opposite side DRGs was used as control. One month after the procedure the animal was euthanized. The lumbar region of the spine was placed in 10% formaldehyde for a month. After this fixation DRG samples were prepared for slide analysis. They were embedded in paraffin in order to obtain 3mm thick sections, which were then cut by microtome and collected on slide glasses. Using standard immunohistochemical reactions, the materials were tinted to define biomarkers neurofilaments (NF), glial fibrillary acidic protein (GFAP), heat shock protein – 70 (Hsp-70) expression and apoptosis by transferase-mediated dUTP nick-end labeling (TUNEL) analysis. Results. The number of cells with NF (26,0 ± 3,0 vs 16,1 ± 3,3; p<0,05), GFAP (12,0 ± 1,3 vs 3,2 ± 0,9; p<0,05) and Hsp-70 (10,0 ± 1,6 vs 4,2 ± 1,0; p<0,05) expression, were larger in the PRF side comparing with the control side. Additionally, glial cells in spinal ganglia of both sides demonstrated immunoreactivity. The instances of apoptosis were not significantly different, in statistical terms, between the control and experimental sides (18,0 ± 4,0 vs 20,0 ± 4,0; p=0,35). Conclusions. PRF in spinal gangliocytes of lumbar region increases neural tissue cytoskeleton factors like NF and GFAP suggesting about active regeneration processes into the cells 1 month after the procedure. Spinal gangliocytes one month after PRF treatment notably increases Hsp-70 expression suggesting about activation of cellular activity and inhibitory role reducing of oxidative stress. Similar number of apoptotic cells in spinal ganglia of lumbar region after PRF and control side suggests about inhibitory role of PRF on programmed cell death and stimulation of cell survival.