Expression and function of P2Y receptors on Müller cells of the postnatal rat retina.
In the postnatal and mature retina, many processes are controlled by the action of nucleotides. Their effects are partly mediated via activation of metabotropic P2Y receptors. However, little is known about the developmental regulation and cellular localization of P2Y receptor subtypes. Combining immunohistochemical and neurophysiological methods, we investigated the developmental expression of P2Y receptors on Müller cells, the principal macroglial cells of the retina. The P2Y(1) and the P2Y(4) receptors, but no other subtypes, were unequivocally localized on Müller cells. P2Y(1) was expressed from postnatal day 5 (P5) on and mediated a calcium response to ATP in Müller cells as well as a volume regulatory signaling cascade preventing Müller cells from swelling under hypotonic conditions. Differentiation of Müller cells was accompanied by a change of the calcium response pattern; the calcium responses in Müller cell endfeet persisted, but ATP responsiveness of Müller cell somata disappeared. P2Y(4) immunoreactivity was observed in Müller cell endfeet and synaptic terminals of rod bipolar cells from P20 on. Activated protein kinases were detected by immunohistochemistry; p-ERK occurred in Müller cells and amacrine cells, whereas p-Akt was detected in bipolar cells. Our data indicate that purinergic signaling via P2Y(1) and P2Y(4) receptors might contribute to differentiation processes in the postnatal retina.
Paul Flechsig Institute of Brain Research, University of Leipzig, Leipzig, Germany. antje.wurm@medizin.uni-leipzig.de
Antje
A
Wurm
Ines
I
Erdmann
Andreas
A
Bringmann
Andreas
A
Reichenbach
Thomas
T
Pannicke
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000502:physiology*; D009457:Neuroglia / Q000187:drug effects / Q000378:metabolism*; D009997:Osmotic Pressure / Q000187:drug effects / Q000502:physiology; D011494:Protein Kinases / Q000378:metabolism; D051381:Rats; D020318:Rats, Long-Evans; D018048:Receptors, Purinergic P2 / Q000145:classification / Q000378:metabolism*; D058472:Receptors, Purinergic P2Y1; D012160:Retina / Q000166:cytology*; D015398:Signal Transduction / Q000502:physiology
C546384:P2ry1 protein, rat; D018048:Receptors, Purinergic P2; D058472:Receptors, Purinergic P2Y1; C104749:purinoceptor P2Y4; D000255:Adenosine Triphosphate; D011494:Protein Kinases; D002118:Calcium