WIN 55,212-2, Agonist of Cannabinoid Receptors, Prevents Amyloid β1-42 Effects on Astrocytes in Primary Culture

Abstract

Alzheimer´s disease (AD), a neurodegenerative illness involving synaptic dysfunction with extracellular accumulation of Aβ1-42 toxic peptide, glial activation, inflammatory response and oxidative stress, can lead to neuronal death. Endogenous cannabinoid system is implicated in physiological and physiopathological events in central nervous system (CNS), and changes in this system are related to many human diseases, including AD. However, studies on the effects of cannabinoids on astrocytes functions are scarce. In primary cultured astrocytes we studied cellular viability using MTT assay. Inflammatory and oxidative stress mediators were determined by ELISA and Western-blot techniques both in the presence and absence of Aβ1-42 peptide. Effects of WIN 55,212-2 (a synthetic cannabinoid) on cell viability, inflammatory mediators and oxidative stress were also determined. Aβ1-42 diminished astrocytes viability, increased TNF-α and IL-1β levels and p-65, COX-2 and iNOS protein expression while decreased PPAR-γ and antioxidant enzyme Cu/Zn SOD. WIN 55,212-2 pretreatment prevents all effects elicited by Aβ1-42. Furthermore, cannabinoid WIN 55,212-2 also increased cell viability and PPAR-γ expression in control astrocytes. In conclusion cannabinoid WIN 55,212-2 increases cell viability and anti-inflammatory response in cultured astrocytes. Moreover, WIN 55,212-2 increases expression of anti-oxidant Cu/Zn SOD and is able to prevent inflammation induced by Aβ1-42 in cultured astrocytes. Further studies would be needed to assess the possible beneficial effects of cannabinoids in Alzheimer's disease patients.

Cannabinoids prevent the amyloid β‐induced activation of astroglial hemichannels: A neuroprotective mechanism

“…In agreement with this evidence, the Aβ‐induced hemichannel opening was strongly reduced by inhibiting p38 MAP kinase or iNOS, suggesting that the preventive influence of CBs on astroglial hemichannel activity may proceeds by decreasing the production of IL‐1β, TNF‐α, and NO. Similar inhibitory responses on NO production, activation of p38 MAP kinase and cytokine release have been described for CBs in activated astrocytes (Ortega‐Gutierrez et al, ; Sheng et al, ), even in those stimulated with Aβ (Aguirre‐Rueda et al, ). An alternative mechanism of hemichannel regulation to that resulting from covalent modifications (e.g., phosphorylation and/or S‐nitrosylation) is the sorting of hemichannels to the cell surface.…”

Heme oxygenase-1 derived carbon monoxide suppresses Aβ1–42 toxicity in astrocytes

“…Whilst these findings at least superficially agree with some previous studies, 24 others have indicated that A β 1–42 does not alter astrocyte viability, 23 but can disrupt [Ca 2+ ] i 20 . These latter findings contrast with our observations both on viability (Figure 1) and alterations in [Ca 2+ ] i (Figure 2).…”

Astrocytes and Inflammatory Processes in Alzheimer’s Disease

“…Within the glia, astrocytes are the cell type prevalent in the brain [29]. Astrocytes increase neuronal viability and mitochondrial biogenesis, protecting neural cells from oxidative stress and inflammation induced by the toxic amyloid peptide [30][31][32]. Conversely, if chronic inflammation occurs, astrogliosis is triggered, produced by a reaction to inflammation and oxidative stress caused by toxic and inflammatory agents [33].…”

“…Neurons have fewer defenses against ROS than astrocytes and cooperation between them is important for neuronal resistance against ROS [30,142,143]. Astrocytes contribute to the survival of neurons by detoxifying the ROS enzymes (GSH peroxidase and catalase), increasing antioxidant proteins (GSH or glutathione, vitamin E and ascorbate) and the biogenesis of mitochondria and reducing the activity of metals which can produce redox [31,[144][145][146]. The most powerful antioxidant protein in the brain is GSH produced by astrocytes and neurons, but neurons depend on astrocytes because they do not use extracellular cysteine efficiently and, therefore, need astrocytes to supply it.…”