Effect of polyphenolic phytochemicals on ectopic oxidative phosphorylation in rod outer segments of bovine retina.
OBJECTIVE
The rod outer segments (OS) of the retina are specialized organelles where phototransduction takes place. The mitochondrial electron transport complexes I-IV, cytochrome c and Fo F1 -ATP synthase are functionally expressed in the OS disks. Here, we have studied the effect of some polyphenolic compounds acting as inhibitors of mitochondrial ATPase/synthase activity on the OS ectopic Fo F1 - ATP synthase. The mechanism of apoptosis in the OS was also investigated studying the expression of cytochrome c, caspase 9 and 3 and Apaf-1.


METHODS
We prepared OS from fresh bovine retinae. Semi-quantitative Western blotting, confocal and electron microscopy, and cytofluorimetry were used along with biochemical analyses such as oximetry, ATP synthesis and hydrolysis.


RESULTS
Resveratrol and curcumin plus piperine inhibited ATP synthesis and oxygen consumption in the OS. Epigallocatechin gallate and quercetin inhibited ATP hydrolysis and oxygen consumption in the OS. Malondialdehyde and hydrogen peroxide were produced in respiring OS in the presence of substrates. Cytochrome c was located inside the disk membranes. Procaspase 9 and 3, as well as Apaf-1 were expressed in the OS.


CONCLUSIONS
These polyphenolic phytochemicals modulated the Fo F1 -ATP synthase activity of the the OS reducing production of reactive oxygen intermediates by the OS ectopic electron transport chain. Polyphenols decrease membrane peroxidation and cytochrome c release from disks, preventing the induction of caspase-dependent apoptosis in the OS Such effects are relevant in the design of protection against functional impairment of the OS following oxidative stress from exposure to intense illumination.
Department of Pharmacy-DIFAR, Biochemistry and Physiology Laboratory, University of Genoa, Genova, Italy.
Daniela
D
Calzia
Department of Pharmacy-DIFAR, Biochemistry and Physiology Laboratory, University of Genoa, Genova, Italy.
Michele
M
Oneto
Department of Biology, Università di Padova, Padova, Italy.
Federico
F
Caicci
Department of Nanophysics, Istituto Italiano di Tecnologia, Genova, Italy.
Paolo
P
Bianchini
Department of Pharmacy-DIFAR, Biochemistry and Physiology Laboratory, University of Genoa, Genova, Italy.
Silvia
S
Ravera
Department of Pharmacy-DIFAR, Biochemistry and Physiology Laboratory, University of Genoa, Genova, Italy.
Martina
M
Bartolucci
Department of Nanophysics, Istituto Italiano di Tecnologia, Genova, Italy.
Alberto
A
Diaspro
UOC Mutagenesi, IRCCS Azienda Ospedaliera Universitaria San Martino - Istituto Nazionale per la Ricerca sul Cancro, Genova, Italy.
Paolo
P
Degan
Department of Biology, Università di Padova, Padova, Italy.
Lucia
L
Manni
Clinica Oculistica, Di.N.O.G.M.I., University of Genoa, IRCCS Azienda Ospedaliera Universitaria San Martino - Istituto Nazionale per la Ricerca sul Cancro, Genova, Italy.
Carlo Enrico
CE
Traverso
Department of Pharmacy-DIFAR, Biochemistry and Physiology Laboratory, University of Genoa, Genova, Italy.
Isabella
I
Panfoli
D000255:Adenosine Triphosphate / Q000096:biosynthesis / Q000378:metabolism; D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D052117:Benzodioxoles / Q000494:pharmacology; D053148:Caspase 3 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D002392:Catechin / Q000031:analogs & derivatives / Q000494:pharmacology; D002417:Cattle; D003474:Curcumin / Q000494:pharmacology; D045304:Cytochromes c / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D008315:Malondialdehyde / Q000378:metabolism; D010085:Oxidative Phosphorylation / Q000187:drug effects*; D010101:Oxygen Consumption / Q000187:drug effects; D064209:Phytochemicals / Q000494:pharmacology*; D010880:Piperidines / Q000494:pharmacology; D053284:Polyunsaturated Alkamides / Q000494:pharmacology; D011794:Quercetin / Q000494:pharmacology; D000077185:Resveratrol; D012374:Rod Cell Outer Segment / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D013267:Stilbenes / Q000494:pharmacology
D000470:Alkaloids; D052117:Benzodioxoles; D064209:Phytochemicals; D010880:Piperidines; D053284:Polyunsaturated Alkamides; D013267:Stilbenes; D008315:Malondialdehyde; D000255:Adenosine Triphosphate; D002392:Catechin; D045304:Cytochromes c; D011794:Quercetin; D006861:Hydrogen Peroxide; C045651:epigallocatechin gallate; D053148:Caspase 3; D053453:Caspase 9; D003474:Curcumin; D000077185:Resveratrol; C008922:piperine