Llorente-Ovejero Alberto, Bengoetxea de Tena Iker, Martínez-Gardeazabal Jonatan, Moreno-Rodríguez Marta, Lombardero Laura, Manuel Iván, Rodríguez-Puertas Rafael
Department of Pharmacology, University of the Basque Country (UPV/EHU), Leioa 48940, Spain.
Neurodegenerative Diseases, Biocruces Bizkaia Health Research Institute, Barakaldo 48903, Spain.
ACS Pharmacol Transl Sci. 2022 Aug 4;5(9):791-802. doi: 10.1021/acsptsci.2c00069. eCollection 2022 Sep 9.
The endocannabinoid system modulates learning, memory, and neuroinflammatory processes, playing a key role in neurodegeneration, including Alzheimer's disease (AD). Previous results in a rat lesion model of AD showed modulation of endocannabinoid receptor activity in the basalo-cortical pathway following a specific lesion of basal forebrain cholinergic neurons (BFCNs), indicating that the glial neuroinflammatory response accompanying the lesion is related to endocannabinoid signaling. In this study, 7 days after the lesion, decreased astrocyte and increased microglia immunoreactivities (GFAP and Iba-1) were observed, indicating microglia-mediated neuroinflammation. Using autoradiographic studies, the density and functional coupling to G-proteins of endocannabinoid receptor subtypes were studied in tissue sections from different brain areas where microglia density increased, using CB and CB selective agonists and antagonists. In the presence of the specific CB receptor antagonist, SR141716A, [H]CP55,940 binding (receptor density) was completely blocked in a dose-dependent manner, while the selective CB receptor antagonist, SR144528, inhibited binding to 25%, at best. [S]GTPγS autoradiography (receptor coupling to G-proteins) evoked by CP55,940 (CB/CB agonist) and HU308 (more selective for CB) was abolished by SR141716A in all areas, while SR144528 blocked up to 51.8% of the coupling to G-proteins evoked by CP55,940 restricted to the nucleus basalis magnocellularis. Together, these results demonstrate that there are increased microglia and decreased astrocyte immunoreactivities 1 week after a specific deletion of BFCNs, which projects to cortical areas, where the CB receptor coupling to G-proteins is upregulated. However, at the lesion site, the area with the highest neuroinflammatory response, there is also a limited contribution of CB.
内源性大麻素系统调节学习、记忆和神经炎症过程，在包括阿尔茨海默病（AD）在内的神经退行性变中起关键作用。先前在AD大鼠损伤模型中的研究结果显示，基底前脑胆碱能神经元（BFCNs）发生特定损伤后，基底-皮质通路中的内源性大麻素受体活性受到调节，这表明伴随损伤的胶质细胞神经炎症反应与内源性大麻素信号传导有关。在本研究中，损伤后7天，观察到星形胶质细胞减少，小胶质细胞免疫反应性（GFAP和Iba-1）增加，表明存在小胶质细胞介导的神经炎症。利用放射自显影研究，使用CB和CB选择性激动剂及拮抗剂，在小胶质细胞密度增加的不同脑区的组织切片中，研究了内源性大麻素受体亚型与G蛋白的密度及功能偶联。在存在特异性CB受体拮抗剂SR141716A的情况下，[H]CP55,940结合（受体密度）以剂量依赖性方式被完全阻断，而选择性CB受体拮抗剂SR144528最多只能抑制25%的结合。CP55,940（CB/CB激动剂）和HU308（对CB更具选择性）引发的[S]GTPγS放射自显影（受体与G蛋白的偶联）在所有区域均被SR141716A消除，而SR144528最多只能阻断CP55,940引发的、局限于大细胞基底核的与G蛋白偶联的51.8%。总之，这些结果表明，投射至皮质区域的BFCNs被特异性缺失1周后，小胶质细胞增加，星形胶质细胞免疫反应性降低，且CB受体与G蛋白的偶联上调。然而，在损伤部位，即神经炎症反应最强烈的区域，CB的作用也有限。
