Brain cortical injury induces changes in peripheral lymphocyte ectonucleotidase activities

Abstract

Injury and other pathological conditions induce a massive release of ATP and ADP that initiate an immune response. Extracellular nucleotides are degraded by ectonucleotidases: enzymes from E-NTPDase and E-NPP families sequentially hydrolyze ATP and ADP to AMP, which is further hydrolyzed by ecto-5'-nucleotidase to adenosine that exerts suppressive effects on immune cells. We investigated the ectonucleotidase activities of peripheral lymphocytes at different post-injury times after an unilateral brain injury in the rat. Significant and dynamic changes in the lymphocytic ectonucleotidase activities were obtained. ATP- and ADP-hydrolysis changes, together with their calculated ratios, indicate the major contribution of E-NTPDase 1 and its comparable upregulation between sham operation and injury. AMP hydrolysis changes were more brain-injury specific, with a longer-lasting lymphocytic response induced by cortical stab injury (CSI). In summary, CSI and sham operation induce the upregulation of the whole enzyme chain for adenine nucleotide hydrolysis in lymphocytes, suggesting an important roles of ectonucleotidases in the course of recovery after brain injury.