Revisiting cannabinoid receptor 2 expression and function in murine retina.

The cannabinoid receptor CB2 plays a significant role in the regulation of immune function whereas neuronal expression remains a subject of contention. Multiple studies have described CB2 in retina and a recent study showed that CB2 deletion altered retinal visual processing. We revisited CB2 expression using immunohistochemistry and a recently developed CB2-eGFP reporter mouse. We examined the consequence of acute vs. prolonged CB2 deactivation on the electroretinogram (ERG) responses. We also examined lipidomics in CB2 knockout mice and potential changes in microglia using Scholl analysis. Consistent with a published report, in CB2 receptor knockout mice see an increased ERG scotopic a-wave, as well as stronger responses in dark adapted cone-driven ON bipolar cells and, to a lesser extent cone-driven ON bipolar cells early in light adaptation. Significantly, however, acute block with CB2 antagonist, AM630, did not mimic the results observed in the CB2 knockout mice whereas chronic (7 days) block did. Immunohistochemical studies show no CB2 in retina under non-pathological conditions, even with published antibodies. Retinal CB2–eGFP reporter signal is minimal under baseline conditions but upregulated by intraocular injection of either LPS or carrageenan. CB2 knockout mice see modest declines in a broad spectrum of cannabinoid-related lipids. The numbers and morphology of microglia were unaltered. In summary minimal CB2 expression is seen in healthy retina. CB2 appears to be upregulated under pathological conditions. Previously reported functional consequences of CB2 deletion are an adaptive response to prolonged blockade of these receptors. CB2 therefore impacts retinal signaling but perhaps in an indirect, potentially extra-ocular fashion.post-print8285 K

Cannabinoid CB2R receptors are upregulated with corneal injury and regulate the course of corneal wound healing

CB2R receptors have demonstrated beneficial effects in wound healing in several models. We therefore investigated a potential role of CB2R receptors in corneal wound healing. We examined the functional contribution of CB2R receptors to the course of wound closure in an in vivo murine model. We additionally examined corneal expression of CB2R receptors in mouse and the consequences of their activation on cellular signaling, migration and proliferation in cultured bovine corneal epithelial cells (CECs). Using a novel mouse model, we provide evidence that corneal injury increases CB2R receptor expression in cornea. The CB2R agonist JWH133 induces chemorepulsion in cultured bovine CECs but does not alter CEC proliferation. The signaling profile of CB2R activation is activating MAPK and increasing cAMP accumulation, the latter perhaps due to Gs -coupling. Lipidomic analysis in bovine cornea shows a rise in acylethanolamines including the endocannabinoid anandamide 1 hour after injury. In vivo, CB2R deletion and pharmacological block result in a delayed course of wound closure. In summary, we find evidence that CB2R receptor promoter activity is increased by corneal injury and that these receptors are required for the normal course of wound closure, possibly via chemorepulsion.post-print1,81 M

Interplay between n-3 and n-6 long-chain polyunsaturated fatty acids and the endocannabinoid system in brain protection and repair.

The brain is enriched in arachidonic acid (ARA) and docosahexaenoic acid (DHA), long-chain polyunsaturated fatty acids (LCPUFA) of the n-6 and n-3 series, respectively. Both are essential for optimal brain development and function. Dietary enrichment with DHA and other long-chain n-3 PUFA, such as eicosapentaenoic acid (EPA) have shown beneficial effects on learning and memory, neuroinflammatory processes and synaptic plasticity and neurogenesis. ARA, DHA and EPA are precursors to a diverse repertoire of bioactive lipid mediators, including endocannabinoids. The endocannabinoid system comprises cannabinoid receptors, their endogenous ligands, the endocannabinoids, and their biosynthetic and degradation enzymes. Anandamide (AEA) and 2-archidonoylglycerol (2-AG) are the most widely studied endocannabinoids, and are both derived from phospholipid-bound ARA. The endocannabinoid system also has well established roles in neuroinflammation, synaptic plasticity and neurogenesis, suggesting an overlap in the neuroprotective effects observed with these different classes of lipids. Indeed, growing evidence suggests a complex interplay between n-3 and n-6 LCPUFA and the endocannabinoid system. For example, long-term DHA and EPA supplementation reduces AEA and 2-AG levels, with reciprocal increases in levels of the analogous endocannabinoid-like DHA and EPA-derived molecules. This review summarises current evidence of this interplay and discusses the therapeutic potential for brain protection and repair

Development of diagnostics method of electricalinsulating liquid of transformer equipment

The work is to research the dielectric characteristics of vegetable-based oil during cyclic temperature aging and to determine the parameters necessary for monitoring the state of the oil, and to develop a method for diagnosing an insulating liquid. The research technique included measuring the dielectric constant of the oil and the tangent of dielectric loss for oil that underwent cyclic temperature oxidation. Thermal oxidation consisted in cyclic heating and natural cooling of the sample during the day without exposure to light. This was done to simulate changes of the temperature in the tank of the power transformer with a changing load schedule during the day. For comparison, the dielectric constant of the base sunflower oil was measured, which was stored in a glass container at room temperature without exposure to light. The results showed that the dielectric constant of vegetable-based oil increases linearly in the oxidation process. The increase in permittivity is associated with an increase in the number of polar molecules as a result of the formation of secondary oxidation products. Under the influence of temperature, the chemical composition of the oil changes and the primary oxidation products — hydroperoxides — are formed. Vegetable-based oil oxidation products do not form a precipitate. Instead, the oil begins to thicken and polymerize. The developed method of diagnosing of an insulating liquid is to determine a coefficient proportional to the growth rate of the number of polar molecules in oil. The results show that monitoring only the tangent of dielectric losses does not give information of the state of vegetable-based oil and is not always an indicator of oxidative processes in oil. The thermal oxidation process has a steady effect on the dielectric constant, which indicates changes of the oil as a result of polymerization

Cannabinoids: clearing the smoke on pain, inflammation and neurodegeneration

Linked ArticlesThis article is part of a themed section on Cannabinoids 2013. To view the other articles in this section, see Fagan and Campbell (2014) DOI: 10.1111/bph.12492, Ignatowska-Jankowska et al. (2014) DOI: 10.1111/bph.12298, Ligresti et al. (2014) DOI: 10.1111/bph.12410, Lopez-Rodriguez et al. (2014) DOI: 10.1111/bph.12519, Murataeva et al. (2014) DOI: 10.1111/bph.12411, Okine et al. (2014) DOI: 10.1111/bph.12540, Rodríguez-Cueto et al. (2014) DOI: 10.1111/bph.12283, Stanley and O'Sullivan (2014) DOI: 10.1111/bph.12560, Toguri et al. (2014) DOI: 10.1111/bph.12545, Wu et al. (2014) DOI: 10.1111/bph.12500. Linked articles are: Avraham et al. (2014) DOI: 10.1111/bph.12478, Machado et al. (2014) DOI: 10.1111/bph.12488, Ward et al. (2014) DOI: 10.1111/bph.12439

Cannabinoid CB2R receptors are upregulated with corneal injury and regulate the course of corneal wound healing

CB2R receptors have demonstrated beneficial effects in wound healing in several models. We therefore investigated a potential role of CB2R receptors in corneal wound healing. We examined the functional contribution of CB2R receptors to the course of wound closure in an in vivo murine model. We additionally examined corneal expression of CB2R receptors in mouse and the consequences of their activation on cellular signaling, migration and proliferation in cultured bovine corneal epithelial cells (CECs). Using a novel mouse model, we provide evidence that corneal injury increases CB2R receptor expression in cornea. The CB2R agonist JWH133 induces chemorepulsion in cultured bovine CECs but does not alter CEC proliferation. The signaling profile of CB2R activation is activating MAPK and increasing cAMP accumulation, the latter perhaps due to G$_{\textrm{s}}$-coupling. Lipidomic analysis in bovine cornea shows a rise in acylethanolamines including the endocannabinoid anandamide 1 hour after injury. In vivo, CB2R deletion and pharmacological block result in a delayed course of wound closure. In summary, we find evidence that CB2R receptor promoter activity is increased by corneal injury and that these receptors are required for the normal course of wound closure, possibly via chemorepulsion

Evidence for a GPR18 Role in Chemotaxis, Proliferation, and the Course of Wound Closure in the Cornea

PURPOSE: We previously showed that cannabinoid-related GPR18 receptors are present in murine corneal epithelium but their function remains unknown. The related CB1 receptors regulate corneal healing, possibly via chemotaxis. We therefore examined a potential role for GPR18 in corneal epithelial chemotaxis and wound healing. METHODS: We examined GPR18 mRNA and protein expression in cornea. We additionally examined the GPR18 action in cultured bovine corneal epithelial cells (bCECs) using Boyden and tracking assays, as well as proliferation and signaling. Finally, we examined wound closure in murine corneal explants. RESULTS: GPR18 mRNA was upregulated with injury in mouse cornea. GPR18 protein was present in basal epithelial cells of the mouse and cow, and redistributed to the wound site upon injury. GPR18 ligand N-arachidonoylglycine (NAGly) induced bCEC chemotaxis. The endocannabinoid arachidonoylethanolamine (AEA) also induced chemotaxis via fatty acid amide hydrolase (FAAH) mediated metabolism to NAGly. GPR18 receptor activation additionally induced bCEC proliferation. In an explant model, the GPR18 antagonist O1918 slowed corneal epithelial cell migration and the rate of corneal wound closure. CONCLUSIONS: Corneal GPR18 activation induced both chemotaxis and proliferation in CECs in vitro, and impacted wound healing. GPR18 may contribute to the maintenance of corneal integrity