Expression of major ectonucleotidases after cortical stab brain injury in rats: A real-time PCR study

Ana Parabucki,Sanja Pekovic,Mirjana Stojiljkovic,Ivana Bjelobaba,Danijela Savic,Danijela Laketa,Nadezda Nedeljkovic

doi:10.2298/abs1401148p

Abstract

Ectonucleotidases are cell surface-located enzymes responsible for the extracellular degradation of nucleotides. They are comprised of several protein families: ectonucleoside triphosphate diphosphohydrolases (E-NTPDase), ectonucleotide pyrophosphatase/phosphodiesterases (E-NPPases) and ecto-5?-nucleotidase. Previously we showed that cortical stab injury alters ectonucleotidase activities in the rat brain, but that the specific enzymes responsible for these changes were not identified. In this study we investigated the gene expression of the specific ectonucleotidase enzymes, NTPDase1- 3, NPP1-3 and ecto-5?-nucleotidase, two and seven days after cortical stab injury in rats, using real-time PCR. Two days after the injury we observed only one significant change: the downregulation in NTPDase2 mRNA expression. Our results indicate that traumatic brain injury induces significant upregulation of NTPDase1, NTPDase2 and ecto-5?-nucleotidase transcripts, and the downregulation of NPP1, seven days after the injury. Thus, traumatic brain injury has diverse impacts on ectonucleotidases gene expression, which may be reflected in the enzyme activities and extracellular nucleotide concentrations in the perilesional tissue.

Highlights

Adenine nucleotides and nucleosides are ubiquitously present molecules
NPP1 mRNA expression (Fig. 1D) was not affected by cortical stab injury (CSI) after two days; seven days after the injury it was decreased to about half the level detected in the corresponding sham group (P
We showed that the rates of ATP and ADP hydrolysis follow a biphasic pattern, with initial downregulation in the first 24 hours after the injury, and significant upregulation 15 days after injury (Nedeljkovic et al, 2006)

Summary

Introduction

Adenine nucleotides and nucleosides are ubiquitously present molecules. They have a central role in energy metabolism and play important roles as extracellular messengers (Burnstock, 2013). Once released in the extracellular space, the extracellular actions of nucleotides and nucleosides are mediated through two types of purinergic receptors: receptors P2 and P1. P1 are receptors for nucleosides and are widely expressed in the central nervous system (CNS), and comprise four subtypes of G protein coupled receptors (A1, A2a, A2b and A3). P2 encompasses two classes of ATP/ADP receptors: P2X which are ion channels and P2Y which are G protein coupled receptors. Several subclasses of P2X and P2Y receptors are present in the CNS (Ralevic and Burnstock, 1998)

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