Blockade of ATP P2X7 receptor enhances ischiatic nerve regeneration in mice following a crush injury

Abstract

Preventing damage caused by nerve degeneration is a great challenge. There is a growing body of evidence implicating extracellular nucleotides and their P2 receptors in many pathophysiological mechanisms.In this work we aimed to investigate the effects of the administration of Brilliant Blue G (BBG) and Pyridoxalphosphate-6-azophenyl-20, 40 - disulphonic acid (PPADS), P2X7 and P2 non-selective receptor antagonists, respectively, on sciatic nerve regeneration. Four groups of mice that underwent nerve crush lesion were used: two control groups treated with vehicle (saline), a group treated with BBG and a group treated with PPADS during 28 days. Gastrocnemius muscle weight was evaluated. For functional evaluation we used the Sciatic Functional Index (SFI) and the horizontal ladder walking test. Nerves, dorsal root ganglia and spinal cords were processed for light and electron microscopy. Antinoceptive effects of BBG and PPADS were evaluated through von Frey E, and the levels of IL-1b and TNF-a were analyzed by ELISA. BBG promoted an increase in the number of myelinated fibers and on axon, fiber and myelin areas. BBG and PPADS led to an increase of TNF-a and IL-1b in the nerve on day 1 and PPADS caused a decrease of IL-1b on day 7. Mechanical allodynia was reversed on day 7 in the groups treated with BBG and PPADS. We concluded that BBG promoted a better morphological regeneration after ischiatic crush injury, but this was not followed by anticipation of functional improvement. In addition, both PPADS and BBG presented anti-inflammatory as well as antinociceptive effects.