Extracellular ATP induces retinal photoreceptor apoptosis through activation of purinoceptors in rodents

Theresa Puthussery, Erica Fletcher

Research output: Contribution to journalArticlepeer-review

67 Scopus citations


We have previously demonstrated that photoreceptors express P2X7 purinoceptors. These excitatory receptors are activated by extracellular adenosine 5′-triphosphate (ATP) and have been implicated in neurodegeneration in other parts of the central nervous system (CNS). In this study we examined whether extracellular ATP could contribute to photoreceptor degeneration in rodents through excessive activation of P2 purinoceptors. Intravitreal injection of high concentrations of extracellular ATP into normal rat eyes induced extensive and selective apoptosis at photoreceptors within 18 hours of injection. Five days after injection the outer nuclear layer was severely degenerated and electro-retinographic responses were impaired. Preinjection of the purinergic antagonist pyridoxal-phosphate-6-azophenyl-2′,4′-disulfonic acid (PPADS) protected agains ATP-mediated apoptosis. The initial phase of ATP-induced photoreceptor death did not temporally coincide with retinal pigment epithelium degeneration or microglial activation, suggesting that cell death was due to direct activation of purinergic receptors on photoreceptors. Finally, we demonstrate that intravitreal injection of PPADS results in a 30% increase in photoreceptor survival in the rd1 mouse, as model of human recessive retinitis pigmentosa (RP). These findings highlight the importance of extracellular ATP in retinal neurodegeneration and provide a potential new avenue for therapeutic intervention in RP.

Original languageEnglish (US)
Pages (from-to)430-440
Number of pages11
JournalJournal of Comparative Neurology
Issue number4
StatePublished - Apr 1 2009


  • Microglia
  • P2X receptor
  • Photoreceptor
  • Purine
  • Retinal degeneration
  • Retinal pigment epithelium

ASJC Scopus subject areas

  • Neuroscience(all)


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