Cannabinoid Receptors CB1 and CB2 Modulate the Electroretinographic Waves in Vervet Monkeys

Abstract

The expression patterns of the cannabinoid receptor type 1 (CB1R) and the cannabinoid receptor type 2 (CB2R) are well documented in rodents and primates. In vervet monkeys, CB1R is present in the retinal neurons (photoreceptors, horizontal cells, bipolar cells, amacrine cells, and ganglion cells) and CB2R is exclusively found in the retinal glia (Müller cells). However, the role of these cannabinoid receptors in normal primate retinal function remains elusive. Using full-field electroretinography in adult vervet monkeys, we recorded changes in neural activity following the blockade of CB1R and CB2R by the intravitreal administration of their antagonists (AM251 and AM630, resp.) in photopic and scotopic conditions. Our results show that AM251 increases the photopic a-wave amplitude at high flash intensities, whereas AM630 increases the amplitude of both the photopic a- and b-waves. In scotopic conditions, both blockers increased the b-wave amplitude but did not change the a-wave amplitude. These findings suggest an important role of CB1R and CB2R in primate retinal function.

The Endocannabinoid System in the Vervet Monkey Retina

“…They concluded that CB2R is likely to play a greater role in mouse retinal processing than CB1R. In monkeys, we have recently reported a significant increase in the b-wave component of the scotopic and photopic ERG after a blockade of both CB1R and CB2R with their specific antagonists [61]. This variation can be due to the different pattern of expression and specialization of the ECS in the monkey.…”

“…The function of the cannabinoid receptors in the retina has been highlighted in ERG studies in adult mice [53] and vervet monkeys [61,62]. Cécyre et al [53] demonstrated a significant change in the ERG a-wave of the CB2R knockout dark-adapted mouse but not in CB1R knockouts compared to wild types.…”

Potential for endocannabinoid system modulation in ocular pain and inflammation: filling the gaps in current pharmacological options

“…There is, however, a growing body of evidence indicating potential for ECS-modulation in the treatment of a range of ocular conditions. Both CB1R and CB2R have been identified in various tissues of the human eye, including the cornea (CB1R) [151], ciliary body and ciliary process, trabecular meshwork, retina, and iris [151][152][153] as well as in immune cells present in ocular tissues (CB2R) [139,[154][155][156][157]. Both endocannabinoids (2-AG and AEA) and the enzymes involved in their synthesis and degradation have been identified in various tissues in human eyes, including the cornea, iris, retina, choroid, and ciliary body [157,[158][159][160][161][162][163][164][165].…”

Effects of Prenatal Alcohol Exposure on the Visual System of Monkeys Measured at Different Stages of Development

“…For photopic recordings, stimuli ranging from À2.2 to 2.9 log cd.s.m À2 were then presented at 2-second intervals, with a steady white background (30 cdÁm À2 inside the Ganzfeld; additional details are available in Refs. [37][38][39].…”