Mol Vis. 2008;14:2190-203. Epub 2008 Dec 3.
Neuroprotective Effects of Cannabidiol in Endotoxin-Induced Uveitis: Critical Role of p38 MAPK Activation.
El-Remessy AB, Tang Y, Zhu G, Matragoon S, Khalifa Y, Liu EK, Liu JY, Hanson E, Mian S, Fatteh N, Liou GI.
Department of Ophthalmology, Medical College of Georgia, Augusta, GA 30912, USA.
PURPOSE: Degenerative retinal diseases are characterized by inflammation and microglial activation. The nonpsychoactive cannabinoid, cannabidiol (CBD), is an anti-inflammatory in models of diabetes and glaucoma. However, the cellular and molecular mechanisms are largely unknown. We tested the hypothesis that retinal inflammation and microglia activation are initiated and sustained by oxidative stress and p38 mitogen-activated protein kinase (MAPK) activation, and that CBD reduces inflammation by blocking these processes.
METHODS: Microglial cells were isolated from retinas of newborn rats. Tumor necrosis factor (TNF)-alpha levels were estimated with ELISA. Nitric oxide (NO) was determined with a NO analyzer. Superoxide anion levels were determined by the chemiluminescence of luminol derivative. Reactive oxygen species (ROS) was estimated by measuring the cellular oxidation products of 2', 7'-dichlorofluorescin diacetate.
RESULTS: In retinal microglial cells, treatment with lipopolysaccharide (LPS) induced immediate NADPH oxidase-generated ROS. This was followed by p38 MAPK activation and resulted in a time-dependent increase in TNF-alpha production. At a later phase, LPS induced NO, ROS, and p38 MAPK activation that peaked at 2-6 h and was accompanied by morphological change of microglia. Treatment with 1 microM CBD inhibited ROS formation and p38 MAPK activation, NO and TNF-alpha formation, and maintained cell morphology. In addition, LPS-treated rat retinas showed an accumulation of macrophages and activated microglia, significant levels of ROS and nitrotyrosine, activation of p38 MAPK, and neuronal apoptosis. These effects were blocked by treatment with 5 mg/kg CBD.
CONCLUSIONS: Retinal inflammation and degeneration in uveitis are caused by oxidative stress. CBD exerts anti-inflammatory and neuroprotective effects by a mechanism that involves blocking oxidative stress and activation of p38 MAPK and microglia.
PMCID: PMC2592995, PMID: 19052649 [PubMed - indexed for MEDLINE]
Invest Ophthalmol Vis Sci. 2008 Dec;49(12):5526-31. Epub 2008 Jul 18.
Mediation of Cannabidiol Anti-Inflammation in the Retina by Equilibrative Nucleoside Transporter and A2A Adenosine Receptor.
Liou GI, Auchampach JA, Hillard CJ, Zhu G, Yousufzai B, Mian S, Khan S, Khalifa Y.
Department of Ophthalmology, Medical College of Georgia, Augusta, Georgia 30912, USA.
PURPOSE: Cannabidiol (CBD), a nonpsychotropic, nontoxic compound has been shown to block diabetes- and endotoxin-induced retinal damage. However, the protective mechanism of this anti-inflammatory cannabinoid is not completely understood. The goal of this study is to determine the role of adenosine signaling in retinal inflammation and its potential modulation by CBD.
METHODS: The adenosine receptor (AR) subtypes expressed in rat retinal microglial cells were assessed by quantitative real-time RT-PCR. AR function was determined via in vitro and in vivo inflammatory models. Microglial cells or rats were treated with or without lipopolysaccharide (LPS) in the presence or absence of adenosine, adenosine receptor agonists/antagonists, or CBD. Adenosine uptake and tumor necrosis factor (TNF)-alpha release in cells or in retinas were determined.
RESULTS: The results showed that A(2A)ARs are abundantly expressed in rat retinal microglial cells. When the cells or rats were treated with LPS, activation of the A(2A)AR was the most efficient in mediating AR agonist- or CBD-induced TNF-alpha inhibition. CBD inhibited adenosine uptake via equilibrative nucleoside transporter 1 and synergistically enhanced adenosine's TNF-alpha suppression after treatment with LPS.
CONCLUSIONS: These results suggest that the activated A(2A)AR in the retinal microglial cells plays a major anti-inflammatory role in the retina and that CBD's anti-inflammatory effects are linked to the inhibition of adenosine uptake.
PMCID: PMC2588644, PMID: 18641283 [PubMed - indexed for MEDLINE]
Neuropharmacology. 2008 Jan;54(1):244-9. Epub 2007 Jul 17.
Cannabidiol Arrests Onset of Autoimmune Diabetes in NOD Mice.
Weiss L, Zeira M, Reich S, Slavin S, Raz I, Mechoulam R, Gallily R.
Department of Bone Marrow Transplantation and Cancer Immunotherapy, Hadassah Hebrew University Hospital, Jerusalem 91120, Israel.
We have previously reported that cannabidiol (CBD) lowers the incidence of diabetes in young non-obese diabetes-prone (NOD) female mice. In the present study we show that administration of CBD to 11-14 week old female NOD mice, which are either in a latent diabetes stage or with initial symptoms of diabetes, ameliorates the manifestations of the disease. Diabetes was diagnosed in only 32% of the mice in the CBD-treated group, compared to 86% and 100% in the emulsifier-treated and untreated groups, respectively. In addition, the level of the proinflammatory cytokine IL-12 produced by splenocytes was significantly reduced, whereas the level of the anti-inflammatory IL-10 was significantly elevated following CBD-treatment. Histological examination of the pancreata of CBD-treated mice revealed more intact islets than in the controls. Our data strengthen our previous assumption that CBD, known to be safe in man, can possibly be used as a therapeutic agent for treatment of type 1 diabetes.
PMCID: PMC2270485, PMID: 17714746 [PubMed - indexed for MEDLINE]