The endocannabinoid system in the monkey visual brain.

在拨款的最后期限内，我们在猴子视网膜内内源性大麻素系统的表达、定位和功能方面取得了新颖和开创性的结果。猴子的视觉系统与人类非常相似，这使得它成为一个相当有趣的物种来研究视觉，从而将数据外推到人类。我们已经明确地表明，大麻素受体在特定的视网膜成分中表达，并可能对不同的视觉功能起作用。大麻素受体1(CB1)主要表达于视网膜中央的视锥感光细胞，而大麻素受体2(CB2R)主要表达于视网膜神经胶质细胞(Müler细胞)。第三个可能的内源性大麻素GPR55在杆状感光细胞中表达。这些受体类型对视网膜功能的贡献是通过对视网膜电波(ERG)的作用来评估的。通过玻璃体内注射受体激动剂或阻滞剂，我们能够显示它们对明视和暗视ERG波的不同调制影响。然而，问题仍然是这些大麻素受体在视网膜受体结构的上游表达，主要是初级(丘脑外侧膝状体背侧核)和次级(上丘-枕叶)皮质下中继器以及相关的皮质受体区域，如纹状皮质(V1区)和纹状皮质(V2和V3)。我们还将研究这些受体在传出背侧(例如HMT+区)和腹侧(例如颞下)皮质视觉流中的表达。大麻素受体的表达和定位将用我们实验室目前使用的免疫组织化学方法来测量。将使用视觉诱发皮层电位(VECP)和图形视网膜电反应(PERG)等电生理技术来研究大麻受体在高级视觉功能中的功能，这些技术是视觉敏感度和对比敏感度的良好衡量标准，此外，这些技术是完全非侵入性的，可以在麻醉的制剂上获得。内源性大麻素受体的选择性激动剂或阻断剂将通过其对视觉诱发反应模式的调节作用来突出它们对M(大细胞)和P(小细胞)通路的相对贡献。最后，在活体中对视觉功能(如视力、对比敏感度、视动性眼球震颤、运动)的测量将使用行为技术进行评估，这些技术不需要像目前在人类婴儿身上使用的优先观看那样的长时间训练。拟议项目的结果对于了解大麻对视觉系统从而对视觉发挥作用的机制非常重要。

During the last tenure of the grant, we produced novel and groundbreaking results on the expression, localization and function of the endocannabinoid system in the monkey retina. Monkeys have a very similar visual system to humans and this makes it a rather interesting species to study vision and hence extrapolate data to humans. We have shown unequivocally that the cannabinoid receptors are expressed in specific retinal components and might contribute to diverse visual functions. The cannabinoid receptor 1 (CB1) is mainly expressed in the cone photoreceptors of the central retinal whereas the cannabinoid receptor 2 (CB2R) is mainly found in the retinal glia (Müller cells). The third putative endocannabinoid, GPR55, is expressed in the rod photoreceptors. The contribution of these receptors types to retinal function was assessed through their action on the electroretinographic waves (ERG). Through intravitreous injections of agonists or blockers of the receptors, we were able to show their different modulatory influences on the photopic and scotopic ERG waves. The question remains however on where these cannabinoid receptors are expressed upstream in the retino-recipient structures mainly the primary (dorsal Lateral geniculate nucleus of the thalamus) and the secondary (Superior colliculus-Pulvinar) subcortical relays and the associated cortical recipient areas such the striate cortex (area V1) and the extrastriate cortices (V2 and V3). We will also investigate the expression of these receptors in the efferent dorsal (e.g. area hMT+) and ventral (e.g. inferotemporal) cortical visual streams. The expression and localization of the cannabinoid receptors will be measured with immunohistochemical methods that are currently used in our laboratory. The functions of the cannabinoid receptors on higher visual functions will be investigated using electrophysiological techniques like the Visually Evoked Cortical Potentials (VECP) and pattern electroretinographic responses (PERG) that are good measures of visual acuity and contrast sensitivity with the added advantage that these techniques are totally non-invasive and can be obtained on anesthetized preparations. Selective agonists or blockers of the endocannabinoid receptors will highlight their relative contribution to the M (magnocellular) and P (parvocellular) pathways through their modulatory effects on the visually evoked response patterns. Finally, in vivo measures of visual functions (e.g. visual acuity, contrast sensitivity, optokinetic nystagmus, motion) will be assessed using behavioral techniques that do not require lengthy training such as those currently used in human infants like preferential looking. The results of the proposed project are of great importance for the understanding of the mechanisms by which cannabis sativa exerts its function on the visual system and hence on vision.