Is the Cannabinoid CB2 Receptor a Major Regulator of the Neuroinflammatory Axis of the Neurovascular Unit in Humans?

“The central nervous system (CNS) is an immune privileged site where the neurovascular unit (NVU) and the blood-brain barrier (BBB) act as a selectively permeable interface to control the passage of nutrients and inflammatory cells into the brain parenchyma. However, in response to injury, infection, or disease, CNS cells become activated, and release inflammatory mediators to recruit immune cells to the site of inflammation. Increasing evidence suggests that cannabinoids may have a neuroprotective role in CNS inflammatory conditions. For many years, it was widely accepted that cannabinoid receptor type 1 (CB1) modulates neurological function centrally, while peripheral cannabinoid receptor type 2 (CB2) modulates immune function. As knowledge about the physiology and pharmacology of the endocannabinoid system advances, there is increasing interest in targeting CB2 as a potential treatment for inflammation-dependent CNS diseases (Ashton & Glass, 2007), where recent rodent and human studies have implicated intervention at the level of the NVU and BBB. These are incredibly important in brain health and disease. Therefore, this review begins by explaining the cellular and molecular components of these systems, highlighting important molecules potentially regulated by cannabinoid ligands and then takes an unbiased look at the evidence in support (or otherwise) of cannabinoid receptor expression and control of the NVU and BBB function in humans.” https://www.ncbi.nlm.nih.gov/pubmed/28826541 http://www.sciencedirect.com/science/article/pii/S1054358917300376?via%3Dihub]]>

Neuroprotective activity of cannabinoid receptor-2 against oxidative stress and apoptosis in rat pups having experimentally-induced congenital hypothyroidism.

“In this study, it was aimed to show the cannabinoid receptor-2 (CB2) role, which is a part of neuroprotective endocannabinoidal system, against increasing nitric oxide synthetase (iNOS, eNOS) levels and the apoptotic activity (caspase-3, caspase-9 and DNA in situ fragmentation) within the postnatal critical period in pups of pregnant rats with artificially induced maternal thyroid hormone (TH) deficiency. In conclusion, apoptosis was triggered via oxidative stress in hypothyroid pups. Accordingly, neuroprotective activity of CB2 receptors were motivated spontaneously to resist to CNS lesions during the first 3 weeks of postnatal period.” https://www.ncbi.nlm.nih.gov/pubmed/28799288]]>

Modulation of Astrocyte Activity by Cannabidiol, a Nonpsychoactive Cannabinoid.

“The astrocytes have gained in recent decades an enormous interest as a potential target for neurotherapies, due to their essential and pleiotropic roles in brain physiology and pathology. Their precise regulation is still far from understood, although several candidate molecules/systems arise as promising targets for astrocyte-mediated neuroregulation and/or neuroprotection. The cannabinoid system and its ligands have been shown to interact and affect activities of astrocytes. Cannabidiol (CBD) is the main non-psychotomimetic cannabinoid derived from Cannabis. CBD is devoid of direct CB1 and CB2 receptor activity, but exerts a number of important effects in the brain. Here, we attempt to sum up the current findings on the effects of CBD on astrocyte activity, and in this way on central nervous system (CNS) functions, across various tested models and neuropathologies. The collected data shows that increased astrocyte activity is suppressed in the presence of CBD in models of ischemia, Alzheimer-like and Multiple-Sclerosis-like neurodegenerations, sciatic nerve injury, epilepsy, and schizophrenia. Moreover, CBD has been shown to decrease proinflammatory functions and signaling in astrocytes.” https://www.ncbi.nlm.nih.gov/pubmed/28788104 http://www.mdpi.com/1422-0067/18/8/1669]]>

Neuroprotection by (endo)cannabinoids in glaucoma and retinal neurodegenerative diseases.

“Emerging neuroprotective strategies are being explored to preserve the retina from degeneration, that occurs in eye pathologies like glaucoma, diabetic retinopathy, age-related macular degeneration, and retinitis pigmentosa. Incidentally, neuroprotection of retina is a defending mechanism designed to prevent or delay neuronal cell death, and to maintain neural function following an initial insult, thus avoiding loss of vision. Numerous studies have investigated potential neuroprotective properties of plant-derived phytocannabinoids, as well as of their endogenous counterparts collectively termed endocannabinoids (eCBs), in several degenerative diseases of the retina. eCBs are a group of neuromodulators that, mainly by activating G protein-coupled type-1 and type-2 cannabinoid (CB1 and CB2) receptors, trigger multiple signal transduction cascades that modulate central and peripheral cell functions. A fine balance between biosynthetic and degrading enzymes that control the right concentration of eCBs has been shown to provide neuroprotection in traumatic, ischemic, inflammatory and neurotoxic damage of the brain. Since the existence of eCBs and their binding receptors was documented in the retina of numerous species (from fishes to primates), their involvement in the visual processing has been demonstrated, more recently with a focus on retinal neurodegeneration and neuroprotection. The aim of this review is to present a modern view of the endocannabinoid system, in order to discuss in a better perspective available data from preclinical studies on the use of eCBs as new neuroprotective agents, potentially useful to prevent glaucoma and retinal neurodegenerative diseases.” https://www.ncbi.nlm.nih.gov/pubmed/28738764 http://www.eurekaselect.com/154386/article]]>

Alleviation of Neuropathology by Inhibition of Monoacylglycerol Lipase in APP Transgenic Mice Lacking CB2 Receptors.

Molecular Neurobiology “Inhibition of monoacylglycerol lipase (MAGL), the primary enzyme that hydrolyzes the endocannabinoid 2-arachidonoylglycerol (2-AG) in the brain, produces profound anti-inflammatory and neuroprotective effects and improves synaptic and cognitive functions in animal models of Alzheimer’s disease (AD). However, the molecular mechanisms underlying the beneficial effects produced by inhibition of 2-AG metabolism are still not clear. The cannabinoid receptor type 2 (CB2R) has been thought to be a therapeutic target for AD. Here, we provide evidence, however, that CB2R does not play a role in ameliorating AD neuropathology produced by inactivation of MAGL in 5XFAD APP transgenic mice, an animal model of AD. Our results suggest that CB2R is not required in ameliorating neuropathology and preventing cognitive decline by inhibition of 2-AG metabolism in AD model animals.”
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