Role of cannabinoids and endocannabinoids in cerebral ischemia

Potential of CBD Acting on Cannabinoid Receptors CB1 and CB2 in Ischemic Stroke

Stroke is one of the leading causes of death. It not only affects adult people but also many children. It is estimated that, every year, 15 million people suffer a stroke worldwide. Among them, 5 million people die, while 5 million people are left permanently disabled. In this sense, the research to find new treatments should be accompanied with new therapies to combat neuronal death and to avoid developing cognitive impairment and dementia. Phytocannabinoids are among the compounds that have been used by mankind for the longest period of history. Their beneficial effects such as pain regulation or neuroprotection are widely known and make them possible therapeutic agents with high potential. These compounds bind cannabinoid receptors CB1 and CB2. Unfortunately, the psychoactive side effect has displaced them in the vast majority of areas. Thus, progress in the research and development of new compounds that show efficiency as neuroprotectors without this psychoactive effect is essential. On the one hand, these compounds could selectively bind the CB2 receptor that does not show psychoactive effects and, in glia, has opened new avenues in this field of research, shedding new light on the use of cannabinoid receptors as therapeutic targets to combat neurodegenerative diseases such as Alzheimer's, Parkinson's disease, or stroke. On the other hand, a new possibility lies in the formation of heteromers containing cannabinoid receptors. Heteromers are new functional units that show new properties compared to the individual protomers. Thus, they represent a new possibility that may offer the beneficial effects of cannabinoids devoid of the unwanted psychoactive effect. Nowadays, the approval of a mixture of CBD (cannabidiol) and Δ9-THC (tetrahydrocannabinol) to treat the neuropathic pain and spasticity in multiple sclerosis or purified cannabidiol to combat pediatric epilepsy have opened new therapeutic possibilities in the field of cannabinoids and returned these compounds to the front line of research to treat pathologies as relevant as stroke.

Cannabis, Cannabinoids, and Stroke: Increased Risk or Potential for Protection-A Narrative Review

Worldwide, approximately 15 million people per year suffer from stroke. With about 5 million deaths, stroke is the second most common cause of death and a major cause of long-term disability. It is estimated that about 25% of people older than 85 years will develop stroke. Cannabis sativa and derived cannabinoids have been used for recreational and medical purposes for many centuries. However, due to the legal status in the past, research faced restrictions, and cannabis use was stigmatized for potential negative impacts on health. With the changes in legal status in many countries of the world, cannabis and cannabis-derived substances such as cannabinoids and terpenes have gained more interest in medical research. Several medical effects of cannabis have been scientifically proven, and potential risks identified. In the context of stroke, the role of cannabis is controversial. The negative impact of cannabis use on stroke has been reported through case reports and population-based studies. However, potential beneficial effects of specific cannabinoids are described in animal studies under certain conditions. In this narrative review, the existing body of evidence regarding the negative and positive impacts of cannabis use prior to stroke will be critically appraised.

Hippocampal expression of the cannabinoid receptor type 1 in canine epilepsy

Canine drug-resistant epilepsy is a prevailing issue in veterinary neurology. Alternative or additional treatment with cannabinoids is showing promising results in seizure management. A crucial component of the endocannabinoid system, cannabinoid receptor type 1 (CB1R), is heavily involved in the control of neurotransmitter release. Knowledge of its distribution in the epileptic brain would serve a better understanding of disease pathology and application of cannabinoids in dogs with epilepsy. CB1R distribution was assessed in sub-regions of hippocampus of dogs with idiopathic epilepsy, structural epilepsy and without cerebral pathology. In dogs with idiopathic epilepsy, significantly decreased CB1R expression compared to control animals was observed in CA1. In dogs with structural epilepsy, a significant increase in CB1R signal intensity in comparison to controls was observed. CB1R expression was higher in the structural group as compared to the idiopathic. Double immunofluorescence showed co-localization between CB1R and an astrocytic marker in about 50% of cells, regardless of the diagnosis. In summary, CB1R expression in canine hippocampus undergoes modification by the epileptic process and the direction of this change depends on the etiology of the disease. The distinct disease-associated CB1R expression needs to be considered in new treatment development for dogs with epilepsy.

Protective effect of fatty acid amide hydrolase inhibitor URB597 and monoacylglycerol lipase inhibitor KML29 on renal ischemia-reperfusion injury via toll-like receptor 4/nuclear factor-kappa B pathway

BACKGROUND

Arachidonoyl ethanolamide (anandamide, AEA) and 2-arachidonoylglycerol (2-AG) are the most studies endocannabinoids. AEA and 2-AG are degraded by fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL) enzymes, respectively. FAAH and MAGL enzymes are widely expressed in many tissues, including kidney. Recent works have depicted that AEA and 2-AG levels are associated with ischemia-reperfusion (IR) injury. In this study, we investigated the effects of MAGL inhibitor KML29 and FAAH inhibitor URB597 against kidney IR injury.

METHODS

The kidneys of the rats underwent ischemia for 45 min and then reperfusion for 24 h. KML29 and URB597 were administered intraperitoneally with kidney IR to two different treatment groups.

RESULTS

IR application increased serum blood urea nitrogen (BUN), creatinine (Cre), interleukin-18 (IL-18), neutrophil gelatinase-associated lipocalin (NGAL), and kidney injury molecule-1 (KIM-1) levels, while these parameters were decreased following KML29 and URB597 administration. KML29 and URB597 administration also reduced the increased toll-like receptor-4 (TRL-4), phosphorylated-NF-κB, phosphorylated-IκB-α, tumor necrosis factor alpha (TNF-α), interleukin-1beta (IL-1β), interleukin-6 (IL-6), caspase-3 levels and histopathological damage in kidney tissue.

CONCLUSIONS

Our results reveal that MAGL inhibitor KML29 and FAAH inhibitor URB597 have a protective effect on kidney IR injury by preventing apoptosis and inflammation. Inhibition of MAGL and FAAH may be a new therapeutic strategy to prevent kidney IR injury.

Treadmill Exercise Prevents Cognitive Impairments in Adolescent Intermittent Ethanol Rats by Reducing the Excessive Activation of Microglia Cell in the Hippocampus

The excessive activation of microglia cell induced by adolescent intermittent ethanol (AIE) leads to neuroinflammation in the hippocampus. The endocannabinoid system plays a key role in the modulation of microglia activation. Accumulating evidence suggests that regular exercise improves learning and memory deficits in AIE models. The purpose of this study was to explore the effects of treadmill exercise intervention on the cognitive performance, activation of microglia cells and the expression of monoacylglycerol lipase (MAGL), cannabinoid receptor type 1 (CB1R) and cannabinoid receptor type 2 (CB2R) in the hippocampus of AIE rats. Here, we show that AIE rats exhibited cognitive impairments, whereas the treadmill exercise improves the cognitive performance in AIE rats. In order to explore the possible mechanisms for the exercise-induced attenuation of cognitive disorder, we examined the neuroinflammation in the hippocampus. We found that treadmill exercise led to the decrease in the level of proinflammatory cytokines (IL-1β, IL-6 and TNF-α) and the increase in the level of anti-inflammatory cytokine (IL-10). In addition, we found that treadmill exercise reduced the excessive activation of the microglia cell in the hippocampus of AIE rats. Finally, we found that AIE led to a decrease in the expression of CB1R and CB2R in the hippocampus; however, the treadmill exercise further decreased the expression of CB2R in the hippocampus of AIE rats. Our results suggest that treadmill exercise attenuates AIE-induced neuroinflammation and the excessive activation of hippocampus microglial cells, which may contribute to the exercise-induced improvement of cognitive performance in AIE rats.

Cannabinoids as Glial Cell Modulators in Ischemic Stroke: Implications for Neuroprotection

Stroke is the second leading cause of death worldwide following coronary heart disease. Despite significant efforts to find effective treatments to reduce neurological damage, many patients suffer from sequelae that impair their quality of life. For this reason, the search for new therapeutic options for the treatment of these patients is a priority. Glial cells, including microglia, astrocytes and oligodendrocytes, participate in crucial processes that allow the correct functioning of the neural tissue, being actively involved in the pathophysiological mechanisms of ischemic stroke. Although the exact mechanisms by which glial cells contribute in the pathophysiological context of stroke are not yet completely understood, they have emerged as potentially therapeutic targets to improve brain recovery. The endocannabinoid system has interesting immunomodulatory and protective effects in glial cells, and the pharmacological modulation of this signaling pathway has revealed potential neuroprotective effects in different neurological diseases. Therefore, here we recapitulate current findings on the potential promising contribution of the endocannabinoid system pharmacological manipulation in glial cells for the treatment of ischemic stroke.

Impaired vessel relaxation response and increased infarct size in smooth muscle cannabinoid receptor 1 knockout mice

Cannabinoids are reported to regulate cardiovascular functions. Cannabinoid receptors 1 (CB1Rs) are widely expressed in both the neuronal system and vascular system, but the contribution of CB1Rs in vascular smooth muscle (CB1RSM) to cardiovascular functions is not clear yet. In this research, we analyzed the effects of CB1RSM on blood pressure, vasoconstriction, and vasodilation abilities by using conditionally CB1R knockout mice (CB1RSMKO). The results show no significant difference in basal blood pressure between the conscious CB1RSMKO and control mice, indicating that CB1RSM is not essential for basal blood pressure maintenance. The constriction of the CB1RSMKO mesenteric artery in vitro was not significantly altered compared with that of the control mice. In contrast, the relaxation to CB1R agonist 2-AG or WIN55212-2 was decreased in CB1RSMKO vessels, suggesting that activation of CB1RSM mediates the vasodilation effect of cannabinoids. Ischemia stroke mouse model was used to further identify the potential function of CB1RSM in pathological conditions, and the results showed that the infarct volume in CB1RSMKO mice is significantly increased compared with the control littermates. These results suggest that vascular CB1R may not play a central role in basal vascular health maintenance but is protective in ischemia states, such as stroke. The protection function may be mediated, at least partly, by the relaxation effect of CB1RSM-dependent activities of endocannabinoids.

Role of PI3K/Akt axis in mitigating hippocampal ischemia-reperfusion injury via CB1 receptor stimulation by paracetamol and FAAH inhibitor in rat

AIMS

Acetaminophen or paracetamol (PAR), the recommended antipyretic in COVID-19 and clinically used to alleviate stroke-associated hyperthermia interestingly activates cannabinoid receptor (CB1) through its AM404 metabolite, however, to date, no study reports the in vivo activation of PAR/AM404/CB1 axis in stroke. The current study deciphers the neuroprotective effect of PAR in cerebral ischemia/reperfusion (IR) rat model and unmasks its link with AM404/CB1/PI3K/Akt axis.

MATERIALS AND METHODS

Animals were allocated into 5 groups: (I) sham-operated (SO), (II) IR, (III) IR + PAR (100 mg/kg), (IV) IR + PAR (100 mg/kg) + URB597; anandamide degradation inhibitor (0.3 mg/kg) and (V) IR + PAR (100 mg/kg) + AM4113; CB1 Blocker (5 mg/kg). All drugs were intraperitoneally administered at the inception of the reperfusion period.

KEY FINDINGS

PAR administration alleviated the cognitive impairment in the Morris Water Maze as well as hippocampal histopathological and immunohistochemical examination of GFAP. The PAR signaling was associated with elevation of anandamide level, CB1 receptor expression and survival proteins as p^S473-Akt. P^{(tyr202/thr204)}-ERK1/2 and p^S9-GSK3β. Simultaneously, PAR increased hippocampal BDNF and ß-arrestin1 levels and decreased glutamate level. PAR restores the deranged redox milieu induced by IR Injury, by reducing lipid peroxides, myeloperoxidase activity and NF-κB and increasing NPSH, total antioxidant capacity, nitric oxide and Nrf2 levels. The pre-administration of AM4113 reversed PAR effects, while URB597 potentiated them.

SIGNIFICANCE

PAR poses a significant neuroprotective effect which may be mediated, at least in part, via activation of anandamide/CB1/PI3K/Akt pathway in the IR rat model.

Acteoside isolated from Colebrookea oppositifolia attenuates I/R brain injury in Wistar rats via modulation of HIF-1α, NF-κB, and VEGF pathways

AIMS

The objective of this study was to assess the anti-stroke activity of acteoside isolated from methanolic root extract of C. oppositifolia METHODS: Ischemia-reperfusion(I/R) brain injury was induced in Wistar rats to assess the anti-stroke activity of acteoside. Rats were pretreated with acteoside (10, 25 & 50 mg/kg, p.o.) before the induction of I/R injury. Parameters such as neurological, motor-cognitive functions were evaluated along with morphological (brain volume, infarct size), biochemical (SOD, Catalase, GSH, lipid peroxidation, TNF-α, IL-6, IL-10, ICAM-1, HIF-1α, VEGF, and NF-κB), histopathological, and gene expression studies (HIF-1α, VEGF) were performed to study the protective effect of acteoside against I/R induced brain injury.

RESULTS

I/R injury caused significant deterioration of neurological (p < 0.01), motor (p < 0.01) and cognitive (p < 0.01) functions, associated with increase in the brain volume (p < 0.01), and infarct size (p < 0.01); increase in the levels of MDA, TNF-α, IL-6, ICAM-1, HIF-1α, VEGF, and NF-κB along with significant decrease in SOD, catalase, GSH, and IL-10 (p < 0.01 for all parameters) compared to Sham control group. Histology of brain tissue of disease control group exhibited significant vascular changes, neutrophil infiltration, cerebral oedema, and necrosis of the neuronal cells. Further, the gene-expression studies showed significant increase in the HIF-1α (p < 0.01) and VEGF (p < 0.01) mRNA levels in the I/R control compared to Sham control. Interestingly, the acteoside (10, 25 & 50 mg/kg) has prevented the neurological, motor and cognitive dysfunctions, along with inhibiting the morphological, biochemical, histological and gene expression changes induced by I/R-injury (p < 0.05 for 10 mg; p < 0.01 for 25 & 50 mg/kg of acteoside for all the parameters).

CONCLUSION

These findings suggest that acteoside possess potent anti-stroke activity through modulation of HIF-1α, NF-κB, and VEGF pathway along with its potent antioxidant activity.

Lasting effects of prenatal exposure to Cannabis in the retina of the offspring: an experimental study in mice

Background

Prenatal exposure to Cannabis is a worldwide growing problem. Although retina is part of the central nervous system, the impact of maternal Cannabis use on the retinal development and its postnatal consequences remains unknown. As the prenatal period is potentially sensitive in the normal development of the retina, we hypothesized that recreational use of Cannabis during pregnancy may alter retina structure in the offspring. To test this, we developed a murine model that mimics human exposure in terms of dose and use.

Methods

Pregnant BalbC mice were exposed daily for 5 min to Cannabis smoke (0.2 g of Cannabis) or filtered air, from gestational day 5 to 18 (N = 10/group). After weaning period, pups were separated and examined weekly. On days 60, 120, 200, and 360 after birth, 10 pups from each group were randomly selected for Spectral Domain Optical Coherence Tomography (SD-OCT) analysis of the retina. All retina layers were measured and inner, outer, and total retina thickness were calculated. Other 37 mice from both groups were sacrificed on days 20, 60, and 360 for retinal stereology (total volume of the retina and volume fraction of each retinal layer) and light microscopy. Means and standard deviations were calculated and MANOVA was performed.

Results

The retina of animals which mother was exposed to Cannabis during gestation was 17% thinner on day 120 (young adult) than controls (P = 0.003) due to 21% thinning of the outer retina (P = 0.001). The offspring of mice from the exposed group presented thickening of the IS/OS in comparison to controls on day 200 (P < 0.001). In the volumetric analyzes by retinal stereology, the exposed mice presented transitory increase of the IS/OS total volume and volume fraction on day 60 (young adult) compared to controls (P = 0.008 and P = 0.035, respectively). On light microscopy, exposed mice presented thickening of the IS/OS on day 360 (adult) compared to controls (P = 0.03).

Conclusion

Gestational exposure to Cannabis smoke may cause structural changes in the retina of the offspring that return to normal on mice adulthood. These experimental evidences suggest that children and young adults whose mothers smoked Cannabis during pregnancy may require earlier and more frequent clinical care than the non-exposed population.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40942-021-00314-8.

A focused review on CB2 receptor-selective pharmacological properties and therapeutic potential of β-caryophyllene, a dietary cannabinoid

The endocannabinoid system (ECS), a conserved physiological system emerged as a novel pharmacological target for its significant role and potential therapeutic benefits ranging from neurological diseases to cancer. Among both, CB1 and CB2R types, CB2R have received attention for its pharmacological effects as antioxidant, anti-inflammatory, immunomodulatory and antiapoptotic that can be achieved without causing psychotropic adverse effects through CB1R. The ligands activate CB2R are of endogenous, synthetic and plant origin. In recent years, β-caryophyllene (BCP), a natural bicyclic sesquiterpene in cannabis as well as non-cannabis plants, has received attention due to its selective agonist property on CB2R. BCP has been well studied in a variety of pathological conditions mediating CB2R selective agonist property. The focus of the present manuscript is to represent the CB2R selective agonist mediated pharmacological mechanisms and therapeutic potential of BCP. The present narrative review summarizes insights into the CB2R-selective pharmacological properties and therapeutic potential of BCP such as cardioprotective, hepatoprotective, neuroprotective, nephroprotective, gastroprotective, chemopreventive, antioxidant, anti-inflammatory, and immunomodulator. The available evidences suggest that BCP, can be an important candidate of plant origin endowed with CB2R selective properties that may provide a pharmacological rationale for its pharmacotherapeutic application and pharmaceutical development like a drug. Additionally, given the wide availability in edible plants and dietary use, with safety, and no toxicity, BCP can be promoted as a nutraceutical and functional food for general health and well-being. Further, studies are needed to explore pharmacological and pharmaceutical opportunities for therapeutic and preventive applications of use of BCP in human diseases.

Characterization of CB2 Receptor Expression in Peripheral Blood Monocytes of Acute Ischemic Stroke Patients

Both preclinical and clinical evidence supports the involvement of the endocannabinoid system in the pathobiology of cerebral ischemia. Selective cannabinoid-2 (CB2) receptor agonists exert significant neuroprotection in animal models of focal brain ischemia through a robust anti-inflammatory effect, involving both resident and peripheral immune cells. Nevertheless, no definitive studies demonstrating the relevance of CB2 receptors in human stroke exist.Using rtPCR and flow cytometry assays, we investigated CB2 receptor expression in circulating monocytes from 26 acute ischemic stroke patients and 16 age-matched healthy controls (CT). We also evaluated miR-665 expression, as potential CB2 receptor regulator. The median mRNA levels of CB2 were significantly (p < 0.0001) increased in total monocytes 24 h and 48 h after stroke as compared with CT. This was paralleled by elevation of miR-665 levels in monocytes collected from patients 24 h (p < 0.05 vs CT) and 48 h (p < 0.05 vs CT and p < 0.0001 vs 24 h) after ischemic stroke. Furthermore, an increased percentage of CB2+/CD16+ events, but not CB2+/CD14+ events, was found 24 h [20.17% (IQR, 17.22-23.58)] and 48 h [18.61% (IQR, 15.44-22.06)] after ischemic stroke when compared with CT [10.96% (IQR, 9.185-13.32)]. The percentage of CB2+/CD16+ events in monocytes was positively correlated with NIHSS score at entrance (r = 0.4327, p = 0.027). The potential beneficial functions of CD16+ intermediate and nonclassical monocytes in stroke and the elevated expression of CB2 receptor in these subsets strongly suggest that CB2 receptor agonists can be exploited for the treatment of ischemic stroke patients.

A Systematic Review of Essential Oils and the Endocannabinoid System: A Connection Worthy of Further Exploration

Aromatic compounds have a long history of use as medicines in most recorded cultures. An increasing interest in these therapeutic volatile molecules in both scientific and lay communities has led to the advancement of essential oils as phytomedicines. Recent discoveries suggest essential oils augment the endocannabinoid system in a positive manner to mitigate various pathologies. However, the exact mechanisms whereby essential oils influence endocannabinoid system activity are not fully known, these studies provide a glimpse into their involvement and warrant further evaluation. Additional study of the interaction between essential oils and the endocannabinoid system may lead to promising phytomedicines for the treatment of diseases and conditions involving dysregulation or activation of the endocannabinoid system.

Targeting the endocannabinoid system: a predictive, preventive, and personalized medicine-directed approach to the management of brain pathologies

Cannabis-inspired medical products are garnering increasing attention from the scientific community, general public, and health policy makers. A plethora of scientific literature demonstrates intricate engagement of the endocannabinoid system with human immunology, psychology, developmental processes, neuronal plasticity, signal transduction, and metabolic regulation. Despite the therapeutic potential, the adverse psychoactive effects and historical stigma, cannabinoids have limited widespread clinical application. Therefore, it is plausible to weigh carefully the beneficial effects of cannabinoids against the potential adverse impacts for every individual. This is where the concept of "personalized medicine" as a promising approach for disease prediction and prevention may take into the account. The goal of this review is to provide an outline of the endocannabinoid system, including endocannabinoid metabolizing pathways, and will progress to a more in-depth discussion of the therapeutic interventions by endocannabinoids in various neurological disorders.

Cannabinoid-mediated Modulation of Oxidative Stress and Early Inflammatory Response after Hypoxia-Ischemia

In the process of neonatal encephalopathy, oxidative stress and neuroinflammation have a prominent role after perinatal asphyxia. With the exception of therapeutic hypothermia, no therapeutic interventions are available in the clinical setting to target either the oxidative stress or inflammation, despite the high prevalence of neurological sequelae of this devastating condition. The endocannabinoid system (ECS), recently recognized as a widespread neuromodulatory system, plays an important role in the development of the central nervous system (CNS). This study aims to evaluate the potential effect of the cannabinoid (CB) agonist WIN 55,212-2 (WIN) on reactive oxygen species (ROS) and early inflammatory cytokine production after hypoxia–ischemia (HI) in fetal lambs. Hypoxic–ischemic animals were subjected to 60 min of HI by partial occlusion of the umbilical cord. A group of lambs received a single dose of 0.01 μg/kg WIN, whereas non-asphyctic animals served as controls. WIN reduced the widespread and notorious increase in inflammatory markers tumor necrosis factor (TNF)-α and interleukin (IL)-1β and IL-6 induced by HI, a modulatory effect not observed for oxidative stress. Our study suggests that treatment with a low dose of WIN can alter the profile of pro-inflammatory cytokines 3 h after HI.

Innovative Therapeutic Potential of Cannabinoid Receptors as Targets in Alzheimer’s Disease and Less Well-Known Diseases

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The discovery of cannabinoid receptors at the beginning of the 1990s, CB1 cloned in 1990 and CB2 cloned in 1993, and the availability of selective and potent cannabimimetics could only be justified by the existence of endogenous ligands that are capable of binding to them. Thus, the characterisation and cloning of the first cannabinoid receptor (CB1) led to the isolation and characterisation of the first endocannabinoid, arachidonoylethanolamide (AEA), two years later and the subsequent identification of a family of lipid transmitters known as the fatty acid ester 2-arachidonoylglycerol (2-AG).

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The endogenous cannabinoid system is a complex signalling system that comprises transmembrane endocannabinoid receptors, their endogenous ligands (the endocannabinoids), the specific uptake mechanisms and the enzymatic systems related to their biosynthesis and degradation.

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The endocannabinoid system has been implicated in a wide diversity of biological processes, in both the central and peripheral nervous systems, including memory, learning, neuronal development, stress and emotions, food intake, energy regulation, peripheral metabolism, and the regulation of hormonal balance through the endocrine system.

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In this context, this article will review the current knowledge of the therapeutic potential of cannabinoid receptor as a target in Alzheimer’s disease and other less well-known diseases that include, among others, multiple sclerosis, bone metabolism, and Fragile X syndrome.

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The therapeutic applications will be addressed through the study of cannabinoid agonists acting as single drugs and multi-target drugs highlighting the CB2 receptor agonist.

The Endocannabinoid System Is Present in Rod Outer Segments from Retina and Is Modulated by Light

The aim of the present research was to evaluate if the endocannabinoid system (enzymes and receptors) could be modulated by light in rod outer segment (ROS) from bovine retina. First, we analyzed endocannabinoid 2-arachidonoylglycerol (2-AG) metabolism in purified ROS obtained from dark-adapted (DROS) or light-adapted (LROS) retinas. To this end, diacylglycerol lipase (DAGL), monoacylglycerol lipase (MAGL), and lysophosphatidate phosphohydrolase (LPAP) enzymatic activities were analyzed using radioactive substrates. The protein content of these enzymes and of the receptors to which cannabinoids bind was determined by immunoblotting under light stimulus. Our results indicate that whereas DAGL and MAGL activities were stimulated in retinas exposed to light, no changes were observed in LPAP activity. Interestingly, the protein content of the main enzymes involved in 2-AG metabolism, phospholipase C β₁ (PLCβ₁), and DAGLα (synthesis), and MAGL (hydrolysis), was also modified by light. PLCβ₁ content was increased, while that of lipases was decreased. On the other hand, light produced an increase in the cannabinoid receptors CB1 and CB2 and a decrease in GPR55 protein levels. Taken together, our results indicate that the endocannabinoid system (enzymes and receptors) depends on the illumination state of the retina, suggesting that proteins related to phototransduction phenomena could be involved in the effects observed.

Modulation of the Endocannabinoid System Following Central Nervous System Injury

Central nervous system (CNS) injury, such as stroke or trauma, is known to increase susceptibility to various infections that adversely affect patient outcomes (CNS injury-induced immunodepression-CIDS). The endocannabinoid system (ECS) has been shown to have immunoregulatory properties. Therefore, the ECS might represent a druggable target to overcome CIDS. Evidence suggests that cannabinoid type 2 receptor (CB₂R) activation can be protective during the early pro-inflammatory phase after CNS injury, as it limits neuro-inflammation and, therefore, attenuates CIDS severity. In the later phase post CNS injury, CB₂R inhibition is suggested as a promising pharmacologic strategy to restore immune function in order to prevent infection.

Achyranthes aspera Linn. alleviates cerebral ischemia-reperfusion-induced neurocognitive, biochemical, morphological and histological alterations in Wistar rats

ETHNOPHARMACOLOGICAL RELEVANCE

In the traditional system of Indian medicine, the whole plant and roots of Achyranthes aspera L have been extensively used to treat neurological conditions such as epilepsy and stroke by the various ethnic communities of India.

AIM OF THE STUDY

The present study was aimed to evaluate the cerebroprotective potential of methanol extract of A. aspera aerial parts (MeAA).

MATERIALS AND METHODS

Initially the MeAA was evaluated for total phenolic content and subjected to detailed liquid chromatography-mass spectrometry analysis. Additionally, it was evaluated for in vitro antioxidant activity in ferric reducing antioxidant power, 2, 2-diphenyl-1-picrylhydrazyl and oxygen radical absorbance capacity assays. Furthermore, in RAW 264.7 cell lines the effect of MeAA was evaluated on lipopolysaccharide-induced generation of reactive oxygen species, nitrite and tumor necrosis factor-α. Finally, the MeAA (400 and 800 mg/kg) was evaluated against ischemia-reperfusion (I/R)-induced brain injury in rats. In brief, male Wistar rats were allocated in to five groups (G-I to G-V, n = 10). G-I and G-II assigned as sham control and I/R control, and received only vehicle (carboxy methyl cellulose 0.5% w/v, 10 ml/kg, p.o.). G-III received quercetin (20 mg/kg, p.o.) and assigned as reference standard. G-IV and G-V group animals received 400 and 800 mg/kg oral doses of MeAA, respectively. All the treatments were given orally for a period of seven days and the parameters such as functional (neurological, cognitive and motor), morphological (edema and infarct area), biochemical (superoxide dismutase, catalase, reduced glutathione, lipid peroxidation, cytokines), and histopathological evaluations of the brain tissue was performed.

RESULTS

The MeAA exhibited 72.48 mg gallic acid equivalents/g of total phenolic content and the LC-MS/MS analysis showed acteoside, apigenin, and pentagalloyl glucose as major ingredients in the MeAA. In in vitro antioxidant assays, the MeAA showed good antioxidant activity with IC₅₀ of 126.50 μg/ml in DPPH assay; FRAP and ORAC values of 759.65 and 979.4 in FRAP and ORAC assays, respectively. Further, the MeAA significantly suppressed the generation of ROS, nitrite and TNF-α in LPS activated RAW 264.7 cell lines. Besides, sixty mins of global cerebral ischemia followed by 24 h of reperfusion produced considerable alterations in neurobehavioral functions in the I/R control group compared to sham control, with a significant reduction in catalase and superoxide dismutase enzyme activities. Moreover, there was a significant reduction in reduced glutathione levels with increased lipid peroxidation. Furthermore, the levels of pro-inflammatory cytokines (TNF-α, IL-6, and ICAM-I) increased significantly and those of anti-inflammatory (IL-10) decreased. I/R insult increased the brain volume and aggravated cerebral infarct formation. Histopathological examination of the brain tissue revealed vascular congestion, cerebral edema, leukocyte infiltration, and brain tissue necrosis. Interestingly, seven days pretreatment with MeAA (800 mg/kg, p.o.) has offered significant protection against I/R-induced functional, morphological, biochemical and histopathological alterations in Wistar rats.

CONCLUSIONS

These findings suggest that the MeAA possesses potent cerebroprotective action through its antioxidant and anti-inflammatory mechanisms.

Chemical characterization and cerebroprotective effect of methanolic root extract of Colebrookea oppositifolia in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Colebrookea oppositifolia Smith is one of the extensively used plants to treat neurological conditions such as epilepsy by the various ethnic communities in sub-Himalayan regions of India such as Bhoxa, Tharu and nomadic Gujjars.

AIM OF THE STUDY

This study was conducted to evaluate the cerebroprotective effect of C. oppositifolia methanolic root (MeCO) extract in Wistar rats.

MATERIALS AND METHODS

The MeCO was characterized for total phenolic content and later subjected for detailed liquid chromatography-mass spectrometry analysis. Further, it was evaluated for in vitro antioxidant activity using 2, 2-diphenyl-1-picrylhydrazyl, ferric reducing antioxidant power and oxygen radical absorbance capacity assays. In addition, the MeCO was investigated on generation of ROS, nitrite, and TNF-α in LPS-stimulated RAW 264.7 cell lines. Finally, the cerebroprotective effect of MeCO was examined against global ischemia and reperfusion (I/R)-induced brain injury in Wistar rats. Male Wistar rats were allocated in to five groups (G-I to G-V, n = 10). G-I and G-II served as sham control and I/R control, respectively, and received only vehicle (0.5% w/v carboxy methyl cellulose, 10 ml/kg, p.o.). G-III served as reference standard and received quercetin (20 mg/kg, p.o.). G-IV and G-V animals received 200 and 400 mg/kg oral doses of MeCO, respectively. All the treatments were given for a period of seven days and the parameters such as neurobehavioral (neurological, and cognitive), and motor functions, biochemical (enzymatic and non-enzymatic antioxidants, TNF-α, IL-6, IL-10, ICAM-I), morphological (cerebral edema and infarct area) and histopathological evaluations were performed.

RESULTS

The MeCO showed a total phenolic content of 137.28 mg gallic acid equivalents/g, and LC-MS/MS analysis of MeCO showed presence of acteoside, gossypin, quercetin and ferulic acid as major ingredients (6680.3, 1.55, 3.52 and 431.1 ng/mg). In in vitro antioxidant assays, the MeCO exhibited potent activity with IC₅₀ of 49.10 µg/ml in DPPH assay; FRAP and ORAC values of 1180.5 and 2983.5 respectively. Furthermore, the MeCO significantly inhibited generation of ROS, nitrite and TNF-α in LPS-stimulated RAW 264.7 cell lines. Sixty min of global ischemia with 24 h reperfusion produced substantial alterations in neurobehavioral functions in the I/R control group compared to sham control. In addition, a significant reduction in catalase and superoxide dismutase activities was observed. Moreover, lipid peroxidation increased and reduced glutathione levels decreased significantly. Furthermore, the levels of pro-inflammatory cytokines (TNF-α, IL-6, and ICAM-I) increased significantly and those of anti-inflammatory (IL-10) decreased. I/R insult increased the brain volume and aggravated cerebral infarct formation. Histopathological examination of the rat brain revealed vascular congestion, cerebral edema, leukocyte infiltration, and brain tissue necrosis. Interestingly, seven days pretreatment with MeCO (200 and 400 mg/kg) alleviated all the I/R-induced perturbances (neurobehavioral, and motor functions, biochemical, morphological and histopathological) compared with the I/R control.

CONCLUSIONS

The MeCO exhibit potent cerebroprotective activity through its potent antioxidant and anti-inflammatory mechanisms, and hence may be useful in the management of ischemic stroke and associated complications.

Chemical Proteomic Analysis of Serine Hydrolase Activity in Niemann-Pick Type C Mouse Brain

The endocannabinoid system (ECS) is considered to be an endogenous protective system in various neurodegenerative diseases. Niemann-Pick type C (NPC) is a neurodegenerative disease in which the role of the ECS has not been studied yet. Most of the endocannabinoid enzymes are serine hydrolases, which can be studied using activity-based protein profiling (ABPP). Here, we report the serine hydrolase activity in brain proteomes of a NPC mouse model as measured by ABPP. Two ABPP methods are used: a gel-based method and a chemical proteomics method. The activities of the following endocannabinoid enzymes were quantified: diacylglycerol lipase (DAGL) α, α/β-hydrolase domain-containing protein 4, α/β-hydrolase domain-containing protein 6, α/β-hydrolase domain-containing protein 12, fatty acid amide hydrolase, and monoacylglycerol lipase. Using the gel-based method, two bands were observed for DAGL α. Only the upper band corresponding to this enzyme was significantly decreased in the NPC mouse model. Chemical proteomics showed that three lysosomal serine hydrolase activities (retinoid-inducible serine carboxypeptidase, cathepsin A, and palmitoyl-protein thioesterase 1) were increased in Niemann-Pick C1 protein knockout mouse brain compared to wild-type brain, whereas no difference in endocannabinoid hydrolase activity was observed. We conclude that these targets might be interesting therapeutic targets for future validation studies.

Impact of cannabidiol treatment on regulatory T-17 cells and neutrophil polarization in acute kidney injury

Hallmark features of acute kidney injury (AKI) include mobilization of immune and inflammatory mechanisms culminating in tissue injury. Emerging information indicates heterogeneity of neutrophils with pro- and anti-inflammatory functions (N1 and N2, respectively). Also, regulatory T-17 (Treg17) cells curtail T helper 17 (Th-17)-mediated proinflammatory responses. However, the status of Treg17 cells and neutrophil phenotypes in AKI are not established. Furthermore, cannabidiol exerts immunoregulatory effects, but its impact on Treg17 cells and neutrophil subtypes is not established. Thus, we examined the status of Treg17 cells and neutrophil subtypes in AKI and determined whether cannabidiol favors regulatory neutrophils and T cells accompanied with renoprotection. Accordingly, mice were subjected to bilateral renal ischemia-reperfusion injury (IRI), without or with cannabidiol treatment; thereafter, kidneys were processed for flow cytometry analyses. Renal IRI increased N1 and Th-17 but reduced N2 and Treg17 cells accompanied with disruption of mitochondrial membrane potential (ψ_m) and increased apoptosis/necrosis and kidney injury molecule-1 (KIM-1) immunostaining compared with their sham controls. Importantly, cannabidiol treatment preserved ψ_m and reduced cell death and KIM-1 accompanied by restoration of N1 and N2 imbalance and preservation of Treg17 cells while decreasing Th-17 cells. The ability of cannabidiol to favor development of Treg17 cells was further established using functional mixed lymphocytic reaction. Subsequent studies showed higher renal blood flow and reduced serum creatinine in cannabidiol-treated IRI animals. Collectively, our novel observations establish that renal IRI causes neutrophil polarization in favor of N1 and also reduces Treg17 cells in favor of Th-17, effects that are reversed by cannabidiol treatment accompanied with significant renoprotection.

Experimental ischemia/reperfusion model impairs endocannabinoid signaling and Na+/K+ ATPase expression and activity in kidney proximal tubule cells

LLC-PK1 cells, an immortalized epithelial cell line derived from pig renal proximal tubules, express all the major players of the endocannabinoid system (ECS) such as CB1, CB2 and TRPV1 receptors, as well as the main enzymes involved in the biosynthesis and degradation of the major endocannabinoids named 2-arachidonoylglycerol, 2-AG and anandamide, AEA. Here we investigated whether the damages caused by ischemic insults either in vitro using LLC-PK1 cells exposed to antimycin A (an inductor of ATP-depletion) or in vivo using Wistar rats in a classic renal ischemia and reperfusion (IR) protocol, lead to changes in AEA and 2-AG levels, as well as altered expression of genes from the main enzymes involved in the regulation of the ECS. Our data show that the mRNA levels of the CB1 receptor gene were downregulated, while the transcript levels of monoacylglycerol lipase (MAGL), the main 2-AG degradative enzyme, were upregulated in LLC-PK1 cells after IR model. Accordingly, IR was accompanied by a significant reduction in the levels of 2-AG and AEA, as well as of the two endocannabinoid related molecules, oleoylethanolamide (OEA) and palmitoylethanolamide (PEA) in LLC-PK1 cells. In kidney cortex homogenates, only AEA levels were significantly decreased. In addition, we found that in both the in vitro and in vivo model IR caused a reduction in the expression and activity of the Na⁺/K⁺ ATPase. These changes were reversed by the CB1/CB2 agonist WIN55,212, in a CB1-receptor dependent manner in the LLC-PK1 IR model. In conclusion, the ECS and Na⁺/K⁺ ATPase are down-regulated following IR in LLC-PK1 cells and rat kidney. We suggest that CB1 agonists might represent a potential strategy to reverse the consequences of IR injury in kidney tissues.

Octadecylpropyl Sulfamide Reduces Neurodegeneration and Restores the Memory Deficits Induced by Hypoxia-Ischemia in Mice

The PPAR-α agonist, oleoylethanolamide (OEA) has neuroprotective properties in stroke models. However, its rapid degradation represents a limitation for an effective therapeutic approach. In this study, we evaluated the effects of a stable OEA-modeled compound, octadecylpropyl sulfamide (SUL) on the cognitive, behavioral, cellular and molecular alterations associated with hypoxia-ischemia (HI) in mice. Mice subjected to HI were treated with the PPAR-α antagonist GW6471 (GW) (1 mg/kg) followed 15 min later by SUL (3 and 10 mg/kg). Behavioral, motor, and cognitive tests were carried out 24 h and 7 days after the HI. The levels of microglia, reactive astrocytes and neuronal nuclei were studied using immunofluorescence, and the expression of genes related to the N-acyl-ethanolamides/endocannabinoid signaling systems was determined by qRT-PCR at the end of the experimental sequence. HI induced brain damage in the ipsilateral hippocampus and cortex, which lead to severe memory impairments, and motor coordination deficits. Significant neuronal loss, increased microglia and reactive astrocytes, and compensatory changes in genes associated with the inflammation/immune and endocannabinoid systems were observed in these brain structures of lesioned mice. SUL reversed the memory and motor deficits, decreased the overexpression of microglia and astrocytes, and reduced neurodegeneration induced by HI. Cnr1 and Cnr2 gene expression was modulated by SUL in both sham and HI mice, while Pparα and Faah expression was regulated in HI mice. GW completely blocked the beneficial actions of SUL. These findings suggest that treatment with SUL reduces brain damage and the associated motor and memory deficits induced by HI probably by normalizing the changes in neuroinflammation/immune system mediators.

Acute administration of beta-caryophyllene prevents endocannabinoid system activation during transient common carotid artery occlusion and reperfusion

BACKGROUND

The transient global cerebral hypoperfusion/reperfusion achieved by induction of Bilateral Common Carotid Artery Occlusion followed by Reperfusion (BCCAO/R) has been shown to stimulate early molecular changes that can be easily traced in brain tissue and plasma, and that are indicative of the tissue physiological response to the reperfusion-induced oxidative stress and inflammation. The aim of the present study is to probe the possibility to prevent the molecular changes induced by the BCCAO/R with dietary natural compounds known to possess anti-inflammatory activity, such as the phytocannabinoid beta-caryophyllene (BCP).

METHODS

Two groups of adult Wistar rats were used, sham-operated and submitted to BCCAO/R. In both groups, 6 h before surgery, half of the rats were gavage-fed with a single dose of BCP (40 mg/per rat in 300 μl of sunflower oil as vehicle), while the second half were pre-treated with the vehicle alone. HPLC, Western Blot and immunohistochemistry were used to analyze cerebral cortex and plasma.

RESULTS

After BCCAO/R, BCP prevented the increase of lipoperoxides occurring in the vehicle-treated rats in both cerebral cortex and plasma. In the frontal cortex, BCP further prevented activation of the endocannabinoid system (ECS), spared the docosahexaenoic acid (DHA), appeared to prevent the increase of cyclooxygenase-2 and increased the peroxisome-proliferator activated receptor-alpha (PPAR-alpha) protein levels, while, in plasma, BCP induced the reduction of arachidonoylethanolamide (AEA) levels as compared to vehicle-treated rats.

CONCLUSIONS

Collectively, the pre-treatment with BCP, likely acting as agonist for CB2 and PPAR-alpha receptors, modulates in a beneficial way the ECS activation and the lipoperoxidation, taken as indicative of oxidative stress. Furthermore, our results support the evidence that BCP may be used as a dietary supplement to control the physiological response to the hypoperfusion/reperfusion-induced oxidative stress.

Experimental Cannabinoid 2 Receptor Inhibition in CNS Injury-Induced Immunodeficiency Syndrome

OBJECTIVE

Severe CNS injury, such as stroke, traumatic brain injury, or spinal cord injury, is known to increase susceptibility to infections. The increased susceptibility to infection is due to an impaired immune response and is referred to as CIDS. The CB2 receptor on immune cells presents a potential therapeutic target in CIDS as activation of this receptor has been shown to be involved in immunosuppression. The main purpose of this study was to determine the impact of CB2 receptor inhibition on leukocyte activation within the microcirculation following endotoxin challenge in an experimental stroke model.

METHODS

Five experimental groups (male C57BL/6 mice, age: 6-8 weeks) were subjected to the following treatments: control; endotoxemia (LPS 5 mg/kg, i.v.); transient cerebral hypoxia-ischemia (HI) + endotoxemia; HI + endotoxemia + CB2 receptor antagonist (AM630 2.5 mg/kg, i.v.). HI was induced by unilateral carotid artery occlusion, followed by 50 minute exposure to a low oxygen atmosphere (8% O2 ). The CB2 receptor antagonist was given 15 min prior to LPS administration. Intravital microscopy (IVM) was carried out 2h after LPS administration. Brains were extracted and stained with tetrazolium chloride (TTC) to measure infarct volume.

RESULTS

Compared to endotoxemic animals without CNS injury, mice subjected to HI displayed reduced leukocyte activation in intestinal submucosal venules indicative of CIDS. Administration of the CB2 receptor antagonist in animals with CIDS challenged with endotoxin restored peripheral leukocyte recruitment without a detrimental impact on infarct size.

CONCLUSION

We conclude that the ECS is involved in the impaired immune response following CNS injury. Future studies should further explore the CB2 receptor pathway to develop novel therapies for CIDS.

Involvement of the endocannabinoid system in the physiological response to transient common carotid artery occlusion and reperfusion

Background

The transient global cerebral hypoperfusion/reperfusion achieved by induction of Bilateral Common Carotid Artery Occlusion followed by Reperfusion (BCCAO/R) may trigger a physiological response in an attempt to preserve tissue and function integrity. There are several candidate molecules among which the endocannabinoid system (ECS) and/or peroxisome-proliferator activated receptor-alpha (PPAR-alpha) may play a role in modulating oxidative stress and inflammation. The aims of the present study are to evaluate whether the ECS, the enzyme cyclooxygenase-2 (COX-2) and PPAR-alpha are involved during BCCAO/R in rat brain, and to identify possible markers of the ongoing BCCAO/R-induced challenge in plasma.

Methods

Adult Wistar rats underwent BCCAO/R with 30 min hypoperfusion followed by 60 min reperfusion. The frontal and temporal-occipital cortices and plasma were analyzed by high performance liquid chromatography-mass spectrometry (HPLC-MS) to determine concentrations of endocannabinoids (eCBs) and related molecules behaving as ligands of PPAR-alpha, and of oxidative-stress markers such as lipoperoxides, while Western Blot and immunohistochemistry were used to study protein expression of cannabinoid receptors, COX-2 and PPAR-alpha. Unpaired Student’s t-test was used to evaluate statistical differences between groups.

Results

The acute BCCAO/R procedure is followed by increased brain tissue levels of the eCBs 2-arachidonoylglycerol and anandamide, palmitoylethanolamide, an avid ligand of PPAR-alpha, lipoperoxides, type 1 (CB1) and type 2 (CB2) cannabinoid receptors, and COX-2, and decreased brain tissue concentrations of docosahexaenoic acid (DHA), one of the major targets of lipid peroxidation. In plasma, increased levels of anandamide and lipoperoxides were observed.

Conclusions

The BCCAO/R stimulated early molecular changes that can be easily traced in brain tissue and plasma, and that are indicative of the tissue physiological response to the reperfusion-induced oxidative stress and inflammation. The observed variations suggest that the positive modulation of the ECS and the increase of proinflammatory substances are directly correlated events. Increase of plasmatic levels of anandamide and lipoperoxides further suggests that dysregulation of these molecules may be taken as an indicator of an ongoing hypoperfusion/reperfusion challenge.

Pharmacological hypothermia: a potential for future stroke therapy?

Mild physical hypothermia after stroke has been associated with positive outcomes. Despite the well-studied beneficial effects of hypothermia in the treatment of stroke, lack of precise temperature control, intolerance for the patient, and immunosuppression are some of the reasons which limit its clinical translation. Pharmacologically induced hypothermia has been explored as a possible treatment option following stroke in animal models. Currently, there are eight classes of pharmacological agents/agonists with hypothermic effects affecting a multitude of systems including cannabinoid, opioid, transient receptor potential vanilloid 1 (TRPV1), neurotensin, thyroxine derivatives, dopamine, gas, and adenosine derivatives. Interestingly, drugs in the TRPV1, neurotensin, and thyroxine families have been shown to have effects in thermoregulatory control in decreasing the compensatory hypothermic response during cooling. This review will briefly present drugs in the eight classes by summarizing their proposed mechanisms of action as well as side effects. Reported thermoregulatory effects of the drugs will also be presented. This review offers the opinion that these agents may be useful in combination therapies with physical hypothermia to achieve faster and more stable temperature control in hypothermia.

5-HMF attenuates striatum oxidative damage via Nrf2/ARE signaling pathway following transient global cerebral ischemia

Recent studies have shown 5-hydroxymethyl-2-furfural (5-HMF) has favorable biological effects, and its neuroprotection in a variety of neurological diseases has been noted. Our previous study showed that treatment of 5-HMF led to protection against permanent global cerebral ischemia. However, the underlying mechanisms in cerebral ischemic injury are not fully understood. This study was conducted to investigate the neuroprotective effect of 5-HMF and elucidate the nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response element (ARE) signaling pathway mechanism in the striatum after transient global cerebral ischemia. C57BL/6 mice were subjected to bilateral common carotid artery occlusion for 20 min and sacrificed 24 h after reperfusion. 5-HMF (12 mg/kg) or an equal volume of vehicle was intraperitoneally injected 30 min before ischemia and 5 min after the onset of reperfusion. At 24 h after reperfusion, neurological function was evaluated by neurological disability status scale, locomotor activity test and inclined beam walking test. Histological injury of the striatum was observed by cresyl violet staining and terminal deoxynucleotidyl transferase (TdT)-mediated dNTP nick end labeling (TUNEL) staining. Oxidative stress was evaluated by the carbonyl groups introduced into proteins, and malondialdehyde (MDA) levels. An enzyme-linked immunosorbent assay (ELISA)-based measurement was used to detect Nrf2 DNA binding activity. Nrf2 and its downstream ARE pathway protein expression such as heme oxygenase-1, NAD (P)H:quinone oxidoreductase 1, glutamate-cysteine ligase catalytic subunit and glutamate-cysteine ligase modulatory subunit were detected by western blot. Our results showed that 5-HMF treatment significantly ameliorated neurological deficits, reduced brain water content, attenuated striatum neuronal damage, decreased the carbonyl groups and MDA levels, and activated Nrf2/ARE signaling pathway. Taken together, these results demonstrated that 5-HMF exerted significant antioxidant and neuroprotective effects following transient cerebral ischemia, possibly through the activation of the Nrf2/ARE signaling pathway.

Cannabinoid Type-2 Receptor Drives Neurogenesis and Improves Functional Outcome After Stroke

BACKGROUND AND PURPOSE

Stroke is a leading cause of adult disability characterized by physical, cognitive, and emotional disturbances. Unfortunately, pharmacological options are scarce. The cannabinoid type-2 receptor (CB2R) is neuroprotective in acute experimental stroke by anti-inflammatory mechanisms. However, its role in chronic stroke is still unknown.

METHODS

Stroke was induced by permanent middle cerebral artery occlusion in mice; CB2R modulation was assessed by administering the CB2R agonist JWH133 ((6aR,10aR)-3-(1,1-dimethylbutyl)-6a,7,10,10a-tetrahydro-6,6,9-trimethyl-6H-dibenzo[b,d]pyran) or the CB2R antagonist SR144528 (N-[(1S)-endo-1,3,3-trimethylbicyclo-[2.2.1]-heptan-2-yl]-5-(4-chloro-3-methylphenyl)-1-(4-methylbenzyl)-pyrazole-3-carboxamide) once daily from day 3 to the end of the experiment or by CB2R genetic deletion. Analysis of immunofluorescence-labeled brain sections, 5-bromo-2´-deoxyuridine (BrdU) staining, fluorescence-activated cell sorter analysis of brain cell suspensions, and behavioral tests were performed.

RESULTS

SR144528 decreased neuroblast migration toward the boundary of the infarct area when compared with vehicle-treated mice 14 days after middle cerebral artery occlusion. Consistently, mice on this pharmacological treatment, like mice with CB2R genetic deletion, displayed a lower number of new neurons (NeuN⁺/BrdU⁺ cells) in peri-infarct cortex 28 days after stroke when compared with vehicle-treated group, an effect accompanied by a worse sensorimotor performance in behavioral tests. The CB2R agonist did not affect neurogenesis or outcome in vivo, but increased the migration of neural progenitor cells in vitro; the CB2R antagonist alone did not affect in vitro migration.

CONCLUSIONS

Our data support that CB2R is fundamental for driving neuroblast migration and suggest that an endocannabinoid tone is required for poststroke neurogenesis by promoting neuroblast migration toward the injured brain tissue, increasing the number of new cortical neurons and, conceivably, enhancing motor functional recovery after stroke.

Lessons from Metabonomics on the Neurobiology of Stroke

The application of metabonomic science to interrogate stroke permits the study of metabolite entities, small enough to cross the blood-brain barrier, that provide insight into neuronal dysfunction, and may serve as reservoirs of biomarker discovery. This systematic review examines the applicability of metabolic profiling in ischemic stroke research. Six human studies utilizing metabolic profiling to analyze biofluids from ischemic stroke patients have been included, employing ¹H-NMR and/or mass spectrometry to analyze plasma, serum, and/or urine in a targeted or untargeted fashion. Three are diagnostic studies, and one investigates prognostic biomarkers of stroke recurrence following transient ischemic attack. Two studies focus on metabolic distinguishers of depression or cognitive impairment following stroke. Identified biomarkers from blood and urine predominantly relate to homocysteine and folate, branched chain amino acid, and lipid metabolism. Statistical models are well fitted and reproducible, with excellent validation outcomes, demonstrating the feasibility of metabolic profiling to study a complex disorder with multicausal pathology, such as stroke.

Increased Renal 2-Arachidonoylglycerol Level Is Associated with Improved Renal Function in a Mouse Model of Acute Kidney Injury

Background: Acute kidney injury (AKI) is associated with a significantly increased risk of morbidity and mortality. Ischemia-reperfusion injury (IRI) is a major cause of AKI. In this study, we investigated the role of the endocannabinoid (EC) system in renal IRI using a well-established mouse model. Materials and Methods: Renal ischemia was induced in male C57BL/6 mice by clamping both kidney pedicles for 30 min followed by 24 h of reperfusion. To increase renal 2-arachidonoylglycerol (2-AG) levels, mice were pretreated with JZL184 (16 mg/kg), 30 min before IRI. Serum creatinine and blood urea nitrogen (BUN), renal tubular damage, renal content of ECs and renal expression of markers of inflammation and oxidative stress were measured. Results: Renal IRI was associated with significantly increased serum BUN and creatinine, increased tubular damage score, increased expression of renal markers of inflammation and oxidative stress and elevated renal 2-AG content. Pretreatment with JZL184 was associated with a significant increase in renal 2-AG content and there was also improved serum BUN, creatinine and tubular damage score. However, renal expression of inflammation and oxidative stress markers remained unchanged. Conclusions: This is the first report documenting that renal IRI is associated with an increase in kidney 2-AG content. Further enhancement of 2-AG levels using JZL184 improved indices of renal function and histology, but did not lower renal expression of markers of inflammation and oxidative stress. Further studies are needed to determine the mechanisms responsible for the effects observed and the potential value of 2-AG as a therapeutic target in renal IRI.

Cannabis, Cannabinoids, and Cerebral Metabolism: Potential Applications in Stroke and Disorders of the Central Nervous System

No compound has generated more attention in both the scientific and recently in the political arena as much as cannabinoids. These diverse groups of compounds referred collectively as cannabinoids have both been vilified due to its dramatic and potentially harmful psychotropic effects and glorified due to its equally dramatic and potential application in a number of acute and chronic neurological conditions. Previously illegal to possess, cannabis, the plant where natural form of cannabinoids are derived, is now accepted in a growing number of states for medicinal purpose, and some even for recreational use, increasing opportunities for more scientific experimentation. The purpose of this review is to summarize the growing body of literature on cannabinoids and to present an overview of our current state of knowledge of the human endocannabinoid system in the hope of defining the future of cannabinoids and its potential applications in disorders of the central nervous system, focusing on stroke.

The CB1 antagonist, SR141716A, is protective in permanent photothrombotic cerebral ischemia

Modulation of the endocannabinoid system has been shown to have a significant impact on outcomes in animal models of stroke. We have previously reported a protective effect of the CB1 antagonist, SR141716A, in a transient reperfusion mouse model of cerebral ischemia. This protective effect was in part mediated by activation of the 5HT1A receptor. Here we have examined its effect in a mouse model of permanent ischemia induced by photoinjury. The CB1 antagonist was found to be protective in this model. As was the case following transient ischemia reperfusion, SR141716A (5mg/kg) resulted in smaller infarct fractions and stroke volumes when utilized both as a pretreatment and as a post-treatment. In contrast to the effect in a transient ischemia model, the pretreatment effect did not depend on the 5HT1A receptor. Neurological function correlated favorably to the reduction in stroke size when SR141716A was given as a pretreatment. With the incidence of stroke predicted to rise in parallel with an ever aging population, understanding mechanisms underlying ischemia and therapeutics remains a paramount goal of research.

Expression of the Endocannabinoid Receptor 1 in Human Stroke: An Autoptic Study

OBJECTIVE

Stroke is one of the leading causes of disability and death in the world. The endocannabinoid (eCB) system is upregulated in several neurological diseases including stroke. A previous animal study demonstrated an increased expression of the endocannabinoid receptor 1 (CB1R) in the penumbra area surrounding the ischemic core, suggesting a crucial role in inflammation/reperfusion after stroke. Regarding the localization of CB1/CB2 receptors, animal studies showed that cortical neurons, activated microglia, and astroglia are involved. Our aim was to evaluate the cerebral expression of CB1R in the ischemic brain areas of 9 patients who died due to acute cerebral infarction in the middle cerebral artery territory.

METHODS

The cerebral autoptic tissue was collected within 48 hours since death. Ischemic and contralateral normal-appearing areas were identified. After tissue preprocessing, 4-µm-thick cerebral sections were incubated with the primary CB1R antibodies (Cayman Chemical Company, Ann Arbor, MI). Thereafter, all cerebral sections were hematoxylin treated. In each section, the total cell number and CB1R-positive cells were counted and the CB1R-positive cell count ratio was calculated. For statistical analysis, Student's t-test was used.

RESULTS

In normal tissue, CB1R-positive neurons were the majority; a few non-neuronal cells expressed CB1R. In the ischemic areas, a few neurons were detectable. A significant increase in total CB1R staining was found in the ischemic regions compared to contralateral areas.

CONCLUSIONS

We found an increase in CB1R expression in the ischemic region (neuronal and non-neuronal cell staining), suggesting the inflammatory reaction to the ischemic insult. Whether such response might mediate neuroprotective actions or excitotoxicity-related detrimental effects is still unclear.

Endocannabinoid CB1 receptor activation upon global ischemia adversely impact recovery of reward and stress signaling molecules, neuronal survival and behavioral impulsivity

Global cerebral ischemia in rodents, which mimics cardiac arrest in humans, is associated with a surge in endocannabinoids and increased transmission of dopamine and glutamate leading to excitotoxic cell death. The current study assessed the role of CB1 receptor activation at the moment of an ischemic insult on ensuing regulation of stress and reward signaling molecules, neuronal injury and anxiety-like behavior. Male Wistar rats were separated into 4 groups (n=10/group); sham and ischemic rats administered the CB1 endocannabinoid receptor antagonist AM251 (2mg/kg, i.p.) 30min prior to global cerebral ischemia, and vehicle-treated counterparts. The effects of CB1 receptor blockade on corticotropin-releasing hormone (CRH), vesicular glutamate transporter 2 (vGluT2), tyrosine hydroxylase (TH) and dopamine receptor 1 (DRD1) signaling expression, together with CA1 neuronal damage and anxiety-like behaviors were assessed. Our findings show attenuated CA1 injury and behavioral deficits in AM251-treated ischemic rats. AM251-pretreatment also partially or completely reversed ischemia-induced alterations in TH-ir expression at the hippocampus, ventral tegmental area (VTA), nucleus accumbens (NAc) and basolateral amygdala (BLA), normalized DRD1-ir at the medial forebrain bundle, and diminished BLA and PVN-CRH expression. All groups showed comparable vGluT2 expression at the BLA and PVN-parvocellular subdivision. These findings support a determinant role of CB1 receptor activation at time of ischemia on functional recovery. They also support "state-dependent" effects of endocannabinoids, raising considerations in the development of effective molecules to regulate HPA axis function and mood disorders following cardiac arrest and stroke.

Sevoflurane prevents stroke-induced depressive and anxiety behaviors by promoting cannabinoid receptor subtype I-dependent interaction between β-arrestin 2 and extracellular signal-regulated kinases 1/2 in the rat hippocampus

One of the most frequent psychological consequences of stroke is depression. Previous animal studies have demonstrated that post-conditioning with sevoflurane protects against focal cerebral ischemia and reperfusion injury. Thus, we hypothesized that repeated exposure to sevoflurane after transient ischemia can prevent the development of depressive-like behavior. To test this hypothesis, we induced transient cerebral ischemia via transient occlusion of bilateral common carotid arteries and examined the effects of subsequent repeated exposure to sevoflurane on sucrose preference, locomotor activity, and rearing activity in rats. To explore the putative neurobiological mechanisms, we further investigated the roles of hippocampal CB1 receptor in the behavioral effects of sevoflurane. We found that repeated sevoflurane exposures reversed ischemia-induced depressive-like behaviors. Furthermore, CB1 receptor inhibition in the dorsal hippocampus (DH) abolished the effects of sevoflurane exposures on ischemia-induced depressive-like behaviors. In addition, repeated sevoflurane exposures increased CB1 receptor expression and endocannabinoids levels in the DH of ischemic rats. Moreover, repeated sevoflurane exposures enhanced the expression of β-arrestin 2, increased the activation of extracellular signal-regulated kinases (ERK)1/2, and promoted the interaction of β-arrestin 2 and ERK1/2 in the DH, and such effects were reversed by CB1 receptor antagonism in the DH. Finally, β-arrestin 2 expression and ERK1/2 activation in the DH were critical for the preventative effects of sevoflurane exposures on ischemia-induced depressive-like behaviors. Taken together, our results suggested that sevoflurane exposure after brain ischemia may prevent the development of depression, and such preventative effects of sevoflurane are likely ascribed to the activation of CB1 receptor-mediated β-arrestin 2-ERK1/2 signaling pathways. We propose that the following mechanisms are critical for the preventative effects of sevoflurane against post-stroke depressive and anxiety behaviors: repeated sevoflurane exposure after transient brain ischemia enhances N-arachidonoylethanolamine (AEA) and 2-Arachidonoylglycerol (2-AG) levels and normalize cannabinoid receptor type 1 (CB1) receptor expression in the dorsal hippocampus, which results in enhanced interaction of β-arrestin 2 and extracellular signal-regulated kinases (ERK1/2) and increased ERK1/2 activation, leading to decreased depressive and anxiety behaviors. We think these findings should provide a new strategy for treatment of post-stroke depression.

Cannabidiol and epilepsy: Rationale and therapeutic potential

Despite the introduction of new antiepileptic drugs (AEDs), the quality of life and therapeutic response for patients with epilepsy remains still poor. Unfortunately, besides several advantages, these new AEDs have not satisfactorily reduced the number of refractory patients. Therefore, the need for different other therapeutic options to manage epilepsy is still a current issue. To this purpose, emphasis has been given to phytocannabinoids, which have been medicinally used since ancient time in the treatment of neurological disorders including epilepsy. In particular, the nonpsychoactive compound cannabidiol (CBD) has shown anticonvulsant properties, both in preclinical and clinical studies, with a yet not completely clarified mechanism of action. However, it should be made clear that most phytocannabinoids do not act on the endocannabinoid system as in the case of CBD. In in vivo preclinical studies, CBD has shown significant anticonvulsant effects mainly in acute animal models of seizures, whereas restricted data exist in chronic models of epilepsy as well as in animal models of epileptogenesis. Likewise, clinical evidence seems to indicate that CBD is able to manage epilepsy both in adults and children affected by refractory seizures, with a favourable side effect profile. However, to date, clinical trials are both qualitatively and numerically limited, thus yet inconsistent. Therefore, further preclinical and clinical studies are undoubtedly needed to better evaluate the potential therapeutic profile of CBD in epilepsy, although the actually available data is promising.

The Endocannabinoid System in the Retina: From Physiology to Practical and Therapeutic Applications

Cannabis is one of the most prevalent drugs used in industrialized countries. The main effects of Cannabis are mediated by two major exogenous cannabinoids: ∆9-tetrahydroxycannabinol and cannabidiol. They act on specific endocannabinoid receptors, especially types 1 and 2. Mammals are endowed with a functional cannabinoid system including cannabinoid receptors, ligands, and enzymes. This endocannabinoid signaling pathway is involved in both physiological and pathophysiological conditions with a main role in the biology of the central nervous system. As the retina is a part of the central nervous system due to its embryonic origin, we aim at providing the relevance of studying the endocannabinoid system in the retina. Here, we review the distribution of the cannabinoid receptors, ligands, and enzymes in the retina and focus on the role of the cannabinoid system in retinal neurobiology. This review describes the presence of the cannabinoid system in critical stages of retinal processing and its broad involvement in retinal neurotransmission, neuroplasticity, and neuroprotection. Accordingly, we support the use of synthetic cannabinoids as new neuroprotective drugs to prevent and treat retinal diseases. Finally, we argue for the relevance of functional retinal measures in cannabis users to evaluate the impact of cannabis use on human retinal processing.

Cannabinoid receptor-specific mechanisms to alleviate pain in sickle cell anemia via inhibition of mast cell activation and neurogenic inflammation

Sickle cell anemia is a manifestation of a single point mutation in hemoglobin, but inflammation and pain are the insignia of this disease which can start in infancy and continue throughout life. Earlier studies showed that mast cell activation contributes to neurogenic inflammation and pain in sickle mice. Morphine is the common analgesic treatment but also remains a major challenge due to its side effects and ability to activate mast cells. We, therefore, examined cannabinoid receptor-specific mechanisms to mitigate mast cell activation, neurogenic inflammation and hyperalgesia, using HbSS-BERK sickle and cannabinoid receptor-2-deleted sickle mice. We show that cannabinoids mitigate mast cell activation, inflammation and neurogenic inflammation in sickle mice via both cannabinoid receptors 1 and 2. Thus, cannabinoids influence systemic and neural mechanisms, ameliorating the disease pathobiology and hyperalgesia in sickle mice. This study provides 'proof of principle' for the potential of cannabinoid/cannabinoid receptor-based therapeutics to treat several manifestations of sickle cell anemia.

Endocannabinoids and the Cardiovascular System in Health and Disease

The endocannabinoid system is widely distributed throughout the cardiovascular system. Endocannabinoids play a minimal role in the regulation of cardiovascular function in normal conditions, but are altered in most cardiovascular disorders. In shock, endocannabinoids released within blood mediate the associated hypotension through CB(1) activation. In hypertension, there is evidence for changes in the expression of CB(1), and CB(1) antagonism reduces blood pressure in obese hypertensive and diabetic patients. The endocannabinoid system is also upregulated in cardiac pathologies. This is likely to be cardioprotective, via CB(2) and CB(1) (lesser extent). In the vasculature, endocannabinoids cause vasorelaxation through activation of multiple target sites, inhibition of calcium channels, activation of potassium channels, NO production and the release of vasoactive substances. Changes in the expression or function of any of these pathways alter the vascular effect of endocannabinoids. Endocannabinoids have positive (CB(2)) and negative effects (CB(1)) on the progression of atherosclerosis. However, any negative effects of CB(1) may not be consequential, as chronic CB(1) antagonism in large scale human trials was not associated with significant reductions in atheroma. In neurovascular disorders such as stroke, endocannabinoids are upregulated and protective, involving activation of CB(1), CB(2), TRPV1 and PPARα. Although most of this evidence is from preclinical studies, it seems likely that cannabinoid-based therapies could be beneficial in a range of cardiovascular disorders.

Non-Selective Cannabinoid Receptor Antagonists, Hinokiresinols Reduce Infiltration of Microglia/Macrophages into Ischemic Brain Lesions in Rat via Modulating 2-Arachidonolyglycerol-Induced Migration and Mitochondrial Activity

Growing evidence suggests that therapeutic strategies to modulate the post-ischemic inflammatory responses are promising approaches to improve stroke outcome. Although the endocannabinoid system has been emerged as an endogenous therapeutic target to regulate inflammation after stroke insult, the downstream mechanisms and their potentials for therapeutic intervention remain controversial. Here we identified trans- and cis-hinokiresinols as novel non-selective antagonists for two G-protein-coupled cannabinoid receptors, cannabinoid receptor type 1 and type 2. The Electric Cell-substrate Impedance Sensing and Boyden chamber migration assays using primary microglial cultures revealed that both hinokiresinols significantly inhibited an endocannabinoid, 2-arachidonoylglycerol-induced migration. Hinokiresinols modulated 2-arachidonoylglycerol-induced mitochondrial bioenergetics in microglia as evidenced by inhibition of ATP turnover and reduction in respiratory capacity, thereby resulting in impaired migration activity. In rats subjected to transient middle cerebral artery occlusion (1.5-h) followed by 24-h reperfusion, post-ischemic treatment with hinokiresinols (2 and 7-h after the onset of ischemia, 10 mg/kg) significantly reduced cerebral infarct and infiltration of ED1-positive microglial/macrophage cells into cerebral ischemic lesions in vivo. Co-administration of exogenous 2-AG (1 mg/kg, i.v., single dose at 2 h after starting MCAO) abolished the protective effect of trans-hinokiresionol. These results suggest that hinokiresinols may serve as stroke treatment by targeting the endocannabinoid system. Alteration of mitochondrial bioenergetics and consequent inhibition of inflammatory cells migration may be a novel mechanism underlying anti-ischemic effects conferred by cannabinoid receptor antagonists.

A Cannabinoid Receptor 2 Agonist Prevents Thrombin-Induced Blood-Brain Barrier Damage via the Inhibition of Microglial Activation and Matrix Metalloproteinase Expression in Rats

Thrombin mediates the life-threatening cerebral edema and blood-brain barrier (BBB) damage that occurs after intracerebral hemorrhage (ICH). We previously found that the selective cannabinoid receptor 2 (CB2R) agonist JWH-133 reduced brain edema and neurological deficits following germinal matrix hemorrhage (GMH). We explored whether CB2R stimulation ameliorated thrombin-induced brain edema and BBB permeability as well as the possible molecular mechanism involved. A total of 144 Sprague-Dawley (S-D) rats received a thrombin (20 U) injection in the right basal ganglia. JWH-133 (1.5 mg/kg) or SR-144528 (3.0 mg/kg) and vehicle were intraperitoneally (i.p.) injected 1 h after surgery. Brain water content measurement, Evans blue (EB) extravasation, Western blot, and immunofluorescence were used to study the effects of a CB2R agonist 24 h after surgery. The results demonstrated that JWH-133 administration significantly decreased thrombin-induced brain edema and reduced the number of Iba-1-positive microglia. JWH-133 also decreased the number of P44/P42(+)/Iba-1(+) microglia, lowered Evans blue extravasation, and inhibited the elevated matrix metallopeptidase (MMP)-9 and matrix metallopeptidase (MMP)-12 activities. However, a selective CB2R antagonist (SR-144528) reversed these effects. We demonstrated that CB2R stimulation reduced thrombin-induced brain edema and alleviated BBB damage. We also found that matrix metalloproteinase suppression may be partially involved in these processes.