title: Scotopic vision in the monkey is modulated by the G protein-coupled receptor 55.
abstract: The endogenous cannabinoid system plays important roles in the retina of mice and monkeys via their classic CB1 and CB2 receptors. We have previously reported that the G protein-coupled receptor 55 (GPR55), a putative cannabinoid receptor, is exclusively expressed in rod photoreceptors in the monkey retina, suggesting its possible role in scotopic vision. To test this hypothesis, we recorded full-field electroretinograms (ERGs) after the intravitreal injection of the GPR55 agonist lysophosphatidylglucoside (LPG) or the selective GPR55 antagonist CID16020046 (CID), under light- and dark-adapted conditions. Thirteen vervet monkeys (Chlorocebus sabaeus) were used in this study: four controls (injected with the vehicle dimethyl sulfoxide, DMSO), four injected with LPG and five with CID. We analyzed amplitudes and latencies of the a-wave (photoreceptor responses) and the b-wave (rod and cone system responses) of the ERG. Our results showed that after injection of LPG, the amplitude of the scotopic b-wave was significantly higher, whereas after the injection of CID, it was significantly decreased, compared to the vehicle (DMSO). On the other hand, the a-wave amplitude, and the a-wave and b-wave latencies, of the scotopic ERG responses were not significantly affected by the injection of either compound. Furthermore, the photopic ERG waveforms were not affected by either drug. These results support the hypothesis that GPR55 plays an instrumental role in mediating scotopic vision.
authors.affiliation: School of Optometry,University of Montreal,Montreal,Quebec,Canada.
authors.forename: Joseph
authors.initials: J
authors.lastname: Bouskila
authors.affiliation: School of Optometry,University of Montreal,Montreal,Quebec,Canada.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Harrar
authors.affiliation: School of Optometry,University of Montreal,Montreal,Quebec,Canada.
authors.forename: Pasha
authors.initials: P
authors.lastname: Javadi
authors.affiliation: School of Optometry,University of Montreal,Montreal,Quebec,Canada.
authors.forename: Christian
authors.initials: C
authors.lastname: Casanova
authors.affiliation: Laboratory for Molecular Membrane Neuroscience,RIKEN Brain Science Institute,Wako,Japan.
authors.forename: Yoshio
authors.identifier: 0000-0002-5774-7354
authors.initials: Y
authors.lastname: Hirabayashi
authors.affiliation: Division of Molecular Science,Gunma University,Maebashi,Japan.
authors.forename: Ichiro
authors.initials: I
authors.lastname: Matsuo
authors.affiliation: Division of Molecular Science,Gunma University,Maebashi,Japan.
authors.forename: Jyunpei
authors.initials: J
authors.lastname: Ohyama
authors.affiliation: School of Optometry,University of Montreal,Montreal,Quebec,Canada.
authors.forename: Jean-François
authors.identifier: 0000-0001-9622-6239
authors.initials: JF
authors.lastname: Bouchard
authors.affiliation: School of Optometry,University of Montreal,Montreal,Quebec,Canada.
authors.forename: Maurice
authors.initials: M
authors.lastname: Ptito
mesh_terms: D000818:Animals; D053961:Azabicyclo Compounds / Q000494:pharmacology; D001565:Benzoates / Q000494:pharmacology; D063386:Cannabinoid Receptor Agonists / Q000494:pharmacology; D063387:Cannabinoid Receptor Antagonists / Q000494:pharmacology; D002522:Chlorocebus aethiops; D004596:Electroretinography; D005260:Female; D005994:Glycerophosphates / Q000494:pharmacology; D058449:Intravitreal Injections; D008297:Male; D055254:Night Vision / Q000502:physiology*; D010775:Photic Stimulation; D020419:Photoreceptor Cells, Vertebrate / Q000502:physiology*; D043882:Receptors, Cannabinoid / Q000502:physiology*; D043562:Receptors, G-Protein-Coupled / Q000819:agonists / Q000037:antagonists & inhibitors / Q000502:physiology*
chemical_list: C583126:4-(4-(3-hydroxyphenyl)-3-(4-methylphenyl)-6-oxo-1H,4H,5H,6H-pyrrolo(3,4-c)pyrazol-5-yl)benzoic acid; D053961:Azabicyclo Compounds; D001565:Benzoates; D063386:Cannabinoid Receptor Agonists; D063387:Cannabinoid Receptor Antagonists; D005994:Glycerophosphates; D043882:Receptors, Cannabinoid; D043562:Receptors, G-Protein-Coupled; C017476:lysophosphoglycerides
keywords: CID16020046; Electroretinogram; G protein-coupled receptor 55; LPG; Monkey; Retina