Bouskila Joseph, Harrar Vanessa, Javadi Pasha, Casanova Christian, Hirabayashi Yoshio, Matsuo Ichiro, Ohyama Jyunpei, Bouchard Jean-François, Ptito Maurice
School of Optometry,University of Montreal,Montreal,Quebec,Canada.
Laboratory for Molecular Membrane Neuroscience,RIKEN Brain Science Institute,Wako,Japan.
Vis Neurosci. 2016 Jan;33:E006. doi: 10.1017/S095252381600002X.
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.
内源性大麻素系统通过其经典的CB1和CB2受体在小鼠和猴子的视网膜中发挥重要作用。我们之前报道过，G蛋白偶联受体55（GPR55），一种假定的大麻素受体，在猴子视网膜的视杆光感受器中特异性表达，提示其在暗视觉中可能发挥作用。为了验证这一假设，我们在玻璃体腔内注射GPR55激动剂溶血磷脂酰葡萄糖（LPG）或选择性GPR55拮抗剂CID16020046（CID）后，在明适应和暗适应条件下记录了全视野视网膜电图（ERG）。本研究使用了13只绿猴（Chlorocebus sabaeus）：4只为对照组（注射溶剂二甲基亚砜，DMSO），4只注射LPG，5只注射CID。我们分析了ERG的a波（光感受器反应）和b波（视杆和视锥系统反应）的振幅和潜伏期。我们的结果显示，与溶剂（DMSO）相比，注射LPG后，暗视b波的振幅显著升高，而注射CID后则显著降低。另一方面，暗视ERG反应的a波振幅以及a波和b波潜伏期不受任何一种化合物注射的显著影响。此外，明视ERG波形也不受任何一种药物的影响。这些结果支持了GPR55在介导暗视觉中起重要作用的假设。
