Blockade of P2 Nucleotide Receptors After Spinal Cord Injury Reduced the Gliotic Response and Spared Tissue

Abstract

Spinal cord injury (SCI) triggers a sequel of events commonly associated with cell death and dysfunction of glias and neurons surrounding the lesion. Although astrogliosis and glial scar formation have been involved in both damage and repair processes after SCI, their role remains controversial. Our goal was to investigate the effects of the P2 receptors antagonists, PPADS and suramin, in the establishment of the reactive gliosis and the formation of the glial scar. Molecular biology, immunohistochemistry, spared tissue, and locomotor behavioral studies were used to evaluate astrogliosis, in adult female Sprague-Dawley rats treated with P2 antagonists after moderate injury with the NYU impactor device. Semi-quantitative RT-PCR confirmed the presence of P2Y1, P2Y2, P2Y4, P2Y6, P2Y12 and P2X2 receptors in the adult spinal cord. Immunohistochemistry studies confirmed a significant decrease in GFAP labeled cells at the injury epicenter as well as a decrease in spared tissue after treatment with the antagonists. Functional open field testing revealed no significant locomotor score differences between treated and control animals. Our work is consistent with studies suggesting that astrogliosis is an important event after SCI that limits tissue damage and lesion spreading.

Purinergic Receptors in Spinal Cord-Derived Ependymal Stem/Progenitor Cells and Their Potential Role in Cell-Based Therapy for Spinal Cord Injury

“…Preceding studies reported that the expression of P2X 4 and P2Y 2 receptors can be significantly increased during the acute and chronic stages of SCI (38,41). Here we analyzed the expression of P2X 4 , P2X 7 , P2Y 1 , and P2Y 4 transcripts at different times after induction of a severe traumatic lesion in the spinal cord of rats at T8 level.…”

“…Although preceding approaches based on spinal cord-derived SPCs from either fetal or adult healthy donors reported only modest or no significant functional improvements during the acute phase of transplantation (31,34), we previously demonstrated that acute transplantation of epSPCis obtained from injured tissue reverses the paralysis associated with spinal cord contusion in rats (28). Moreover, a blockade of P2 nucleotide receptors after SCI reduces the gliosis response and spared tissue (38). Based on these findings, we studied whether epSPCi transplantation immediately after SCI is able to decrease P2X 4 and/or P2X 7 expression in the spinal cord of injured rats.…”

“…Following SCI, large amounts of ATP and other nucleotides are released by the traumatized tissue leading to the activation of purinergic receptors that, in coordination with growth factors, induce lesion remodeling and repair (4,13). Moreover, blockade of purinergic receptors after SCI reduced the gliosis response and diminishes also the formation of a glial scar (38).…”

MicroRNA: Crucial modulator in purinergic signalling involved diseases

“…In brief, the correlation between miR-363-5p and the P2X4 receptor contributes to the dedifferentiation and migration of Schwann cells after nerve injury [64]. In spinal cord injury (SCI), blockage of P2X7 receptors and other purinergic receptors provides neuroprotection in rats [65][66][67]. And a study holds that miR-135a is a potential therapeutic target for SCI because miR-135a downregulation causes overexpression of P2X7 receptors and increases excitotoxicity when exposed to the high concentration of ATP.…”

MicroRNA-135a-5p reduces P2X7-dependent rise in intracellular calcium and protects against excitotoxicity

“…Multiple purinergic receptors are expressed in the spinal cord (Apolloni et al, 2009), some of which become overexpressed after injury (Cavaliere et al 2003;Franke et al 2006;Rodríguez-Zayas et al 2010), including P2X 7 (Gómez-Villafuerteset al 2015;Schwab et al 2005). Blockage of P2X 7 and other purinergic receptors with either pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS), oxidized ATP (oxo-ATP), brilliant blue G (BBG), or the partial agonist Ap 4 A provides neuroprotection in rat models of SCI (Peng et al 2009;Reigada et al 2017;Wang et al 2004;Rodríguez-Zayas et al 2011) and traumatic brain injury (TBI) (Wang et al 2015). Results indicate that blockage reduces neuronal damage, microglial activation, neutrophil infiltration and inflammatory response, leading to increased tissue preservation, although one study has failed to reproduce some of these effects (Marcilloet al 2012).…”