EXTRACELLULAR ADP REGULATES LESION-INDUCED IN VIVO CELL PROLIFERATION AND DEATH IN THE ZEBRAFISH RETINA

ARIADNA BATTISTA; JIMENA RICATTI; PAULA FAILLACE

Congreso; I Reunión Conjunta de Neurociencias; 2009

Taller Argentino de Neurociencias y Sociedad Argentina de Investigación en Neurociencias

Persistent neurogenesis in the adult fish retina has been a valuable tool to study cell proliferation and differentiation processes. Damage of the mature retina activates tissue regeneration from intrinsic germinal cells within different pools of precursors. We have previously demonstrated that endogenous purinergic signals regulate cell proliferation induced by a partial lesion with ouabain.   The aim of this study was to elucidate which of the endogenous extracellular nucleotides regulate cell proliferation and whether they have an effect on cell death.  Zebrafish were lesioned by intravitreal injections of ouabain. Then, apyrase (an enzyme that hydrolyses extracellular nucleotides) or different antagonists of purinergic receptors were injected daily for 6 days in the ouabain-treated eyes. On day 7 cell proliferation or death were determined by using 5-Bromo-2´-deoxyuridine or TUNEL respectively.  We demonstrated that cell proliferation is regulated by ADP via P2Y1 metabotropic receptors since the ADP-activated P2Y1 receptor antagonist MRS2179 completely blocked lesion-induced increases in cell division. In contrast, the ADP-activated P2Y12, 13 receptors antagonist MRS2211 did not affect cell proliferation. Likewise, the injection of an antagonist of adenosine P1 receptors (8-SPT) or a mixture of antagonists for ATP-activated P2Y11 or P2X1, 2, 3 receptors did not modify lesion-induced cell division. We also found a role for purinergic signals in regulating injury-induced cell death. Extracellular nucleotides scavenging by apyrase significantly increased cell death in injured retinas. This effect was partially reproduced by blocking P2Y1 receptors.  This study demonstrates a crucial role for extracellular ADP in the repair of retina following injury.