Effect of P2X7 receptor activation on the retinal blood velocity of diabetic rabbits.
OBJECTIVE
To test the effect of activation of P2X7 receptors on retinal blood velocity in diabetic rabbits.


METHODS
Immunohistochemical analysis was performed on healthy and diabetic rabbit eyes using P2X7 receptor antibodies. Diabetes was induced using alloxan. Retinal blood velocity was measured with the laser speckle circulation analyzer. Visual function was assessed using electroretinography.


RESULTS
Cells in inner retinal layers were positive for anti-P2X7 receptor antibodies in healthy rabbits. The distribution of positive cells extended to outer layers and some small vessels stained in diabetic rabbits. When assayed 24 hours after an intravitreal injection of 150 nmol of benzoylbenzoyl adenosine triphosphate (BzATP), a P2X7 agonist, the retinal blood velocity in healthy rabbits was reduced by approximately 30%; this reduction continued for at least 4 weeks. Only in diabetic rabbits did an injection of 50 nmol of BzATP reduce retinal blood velocity by approximately 30% and the amplitudes of electroretinography a waves, b waves, and oscillatory potentials for at least 4 weeks.


CONCLUSIONS
Soon after the onset of alloxan-induced diabetes, retinal blood velocity and function become more vulnerable to reduction initiated through P2X7 receptors.


CONCLUSIONS
Our findings support the hypothesis that the retinal circulation disorder accelerated by activation of P2X7 receptors may be involved in the early changes of diabetic retinopathy.
Sugiyama
Tetsuya
T
Department of Ophthalmology, Osaka Medical College, Takatsuki, Osaka, Japan.
Oku
Hidehiro
H
Komori
Asako
A
Ikeda
Tsunehiko
T
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology; D001786:Blood Glucose / Q000378:metabolism; D001794:Blood Pressure; D003921:Diabetes Mellitus, Experimental / Q000503:physiopathology*; D003930:Diabetic Retinopathy / Q000503:physiopathology*; D004596:Electroretinography; D007124:Immunoenzyme Techniques; D007429:Intraocular Pressure; D017078:Laser-Doppler Flowmetry; D008297:Male; D058910:Purinergic P2 Receptor Agonists; D011817:Rabbits; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D058486:Receptors, Purinergic P2X7; D012160:Retina / Q000187:drug effects / Q000378:metabolism*; D012171:Retinal Vessels / Q000502:physiology*
D001786:Blood Glucose; D058910:Purinergic P2 Receptor Agonists; D018048:Receptors, Purinergic P2; D058486:Receptors, Purinergic P2X7; C033901:3'-O-(4-benzoyl)benzoyladenosine 5'-triphosphate; D000255:Adenosine Triphosphate