Cannabidiol in experimental cerebral ischemia

The absence of blood flow in cerebral ischemic conditions triggers a multitude of intricate pathophysiological mechanisms, including excitotoxicity, oxidative stress, neuroinflammation, disruption of the blood-brain barrier and white matter disarrangement. Despite numerous experimental studies conducted in preclinical settings, existing treatments for cerebral ischemia (CI), such as mechanical and pharmacological therapies, remain constrained and often entail significant side effects. Therefore, there is an imperative to explore innovative strategies for addressing CI outcomes. Cannabidiol (CBD), the most abundant non-psychotomimetic compound derived from Cannabis sativa, is a pleiotropic substance that interacts with diverse molecular targets and has the potential to influence various pathophysiological processes, thereby contributing to enhanced outcomes in CI. This chapter provides a comprehensive overview of the primary effects of CBD in in vitro and diverse animal models of CI and delves into some of its plausible mechanisms of neuroprotection.

The Protective Effect of CBD in a Model of In Vitro Ischemia May Be Mediated by Agonism on TRPV2 Channel and Microglia Activation

Cannabinoids, used for centuries for recreational and medical purposes, have potential therapeutic value in stroke treatment. Cannabidiol (CBD), a non-psychoactive compound and partial agonist of TRPV2 channels, is efficacious in many neurological disorders. We investigated the effects of CBD or Δ9-tetrahydrocannabinol (THC) in rat organotypic hippocampal slices exposed to oxygen-glucose deprivation (OGD), an in vitro model of ischemia. Neuronal TRPV2 expression decreased after OGD, but it increased in activated, phagocytic microglia. CBD increased TRPV2 expression, decreased microglia phagocytosis, and increased rod microglia after OGD. THC had effects contrary to those of CBD. Our results show that cannabinoids have different effects in ischemia. CBD showed neuroprotective effects, mediated, at least in part, by TRPV2 channels, since the TRPV2 antagonist tranilast blocked them, while THC worsened the neurodegeneration caused by ischemia. In conclusion, our results suggest that different cannabinoid molecules play different roles in the mechanisms of post-ischemic neuronal death. These different effects of cannabinoid observed in our experiments caution against the indiscriminate use of cannabis or cannabinoid preparations for recreational or therapeutic use. It was observed that the positive effects of CBD may be counteracted by the negative effects caused by high levels of THC.

Cannabidiol’s Multifactorial Mechanisms Has Therapeutic Potential for Aneurysmal Subarachnoid Hemorrhage: a Review

Subarachnoid hemorrhage (SAH) is a major health burden that accounts for approximately 5% of all strokes. The most common cause of a non-traumatic SAH is the rupture of a cerebral aneurysm. The most common symptom associated with SAH is a headache, often described as “the worst headache of my life.” Delayed cerebral ischemia (DCI) is a major factor associated with patient mortality following SAH and is often associated with SAH-induced cerebral vasospasm (CV). Cannabidiol (CBD) is emerging as a potential drug for many therapeutic purposes, including epilepsy, anxiety, and pain relief. We aim to review the potential use of CBD as a treatment option for post-SAH critically ill patients. Through a literature review, we evaluated the known pharmacology and physiological effects of CBD and correlated those with the pathophysiological outcomes associated with cerebral vasospasm following subarachnoid hemorrhage. Although overlap exists, data were formatted into three major categories: anti-inflammatory, vascular, and neuroprotective effects. Based on the amount of information known about the actions of CBD, we hypothesize the anti-inflammatory effects are likely to be the most promising therapeutic mechanism. However, its cardiovascular effects through calcium regulation and its neuroprotective effects against cell death, excitotoxicity, and oxidative stress are all plausible mechanisms by which post-SAH critically ill patients may benefit from both early and late intervention with CBD. More research is needed to better understand if and how CBD might affect neurological and vascular functions in the brain following injury such as subarachnoid hemorrhage.

Regulation of Expression of Cannabinoid CB2 and Serotonin 5HT1A Receptor Complexes by Cannabinoids in Animal Models of Hypoxia and in Oxygen/Glucose-Deprived Neurons

Background: Cannabidiol (CBD) is a phytocannabinoid with potential in one of the most prevalent syndromes occurring at birth, the hypoxia of the neonate. CBD targets a variety of proteins, cannabinoid CB₂ and serotonin 5HT_1A receptors included. These two receptors may interact to form heteromers (CB₂–5HT_1A-Hets) that are also a target of CBD. Aims: We aimed to assess whether the expression and function of CB₂–5HT_1A-Hets is affected by CBD in animal models of hypoxia of the neonate and in glucose- and oxygen-deprived neurons. Methods: We developed a quantitation of signal transduction events in a heterologous system and in glucose/oxygen-deprived neurons. The expression of receptors was assessed by immuno-cyto and -histochemistry and, also, by using the only existing technique to visualize CB₂–5HT_1A-Hets fixed cultured cells and tissue sections (in situ proximity ligation PLA assay). Results: CBD and cannabigerol, which were used for comparative purposes, affected the structure of the heteromer, but in a qualitatively different way; CBD but not CBG increased the affinity of the CB₂ and 5HT_1A receptor–receptor interaction. Both cannabinoids regulated the effects of CB₂ and 5HT_1A receptor agonists. CBD was able to revert the upregulation of heteromers occurring when neurons were deprived of oxygen and glucose. CBD significantly reduced the increased expression of the CB₂–5HT_1A-Het in glucose/oxygen-deprived neurons. Importantly, in brain sections of a hypoxia/ischemia animal model, administration of CBD led to a significant reduction in the expression of CB₂–5HT_1A-Hets. Conclusions: Benefits of CBD in the hypoxia of the neonate are mediated by acting on CB₂–5HT_1A-Hets and by reducing the aberrant expression of the receptor–receptor complex in hypoxic-ischemic conditions. These results reinforce the potential of CBD for the therapy of the hypoxia of the neonate.

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.

Neuroprotective Effects of Cannabidiol but Not Δ9-Tetrahydrocannabinol in Rat Hippocampal Slices Exposed to Oxygen-Glucose Deprivation: Studies with Cannabis Extracts and Selected Cannabinoids

(1) Background: Over the past 10 years, a number of scientific studies have demonstrated the therapeutic potential of cannabinoid compounds present in the Cannabis Sativa and Indica plants. However, their role in mechanisms leading to neurodegeneration following cerebral ischemia is yet unclear. (2) Methods: We investigated the effects of Cannabis extracts (Bedrocan, FM2) or selected cannabinoids (Δ⁹-tetrahydrocannabinol (THC), cannabidiol (CBD), and cannabigerol) in rat organotypic hippocampal slices exposed to oxygen-glucose deprivation (OGD), an in vitro model of forebrain global ischemia. Cell death in the CA1 subregion of slices was quantified by propidium iodide fluorescence, and morphological analysis and tissue organization were examined by immunohistochemistry and confocal microscopy. (3) Results: Incubation with the Bedrocan extract or THC exacerbated, whereas incubation with the FM2 extract or cannabidiol attenuated CA1 injury induced by OGD. Δ⁹-THC toxicity was prevented by CB1 receptor antagonists, the neuroprotective effect of cannabidiol was blocked by TRPV2, 5-HT1A, and PPARγ antagonists. Confocal microscopy confirmed that CBD, but not THC, had a significant protective effect toward neuronal damage and tissue disorganization caused by OGD in organotypic hippocampal slices. (4) Conclusions: Our results suggest that cannabinoids play different roles in the mechanisms of post-ischemic neuronal death. In particular, appropriate concentrations of CBD or CBD/THC ratios may represent a valid therapeutic intervention in the treatment of post-ischemic neuronal death.

Cannabinoids: A New Perspective on Epileptogenesis and Seizure Treatment in Early Life in Basic and Clinical Studies

Neural hyperexcitability in the event of damage during early life, such as hyperthermia, hypoxia, traumatic brain injury, status epilepticus, or a pre-existing neuroinflammatory condition, can promote the process of epileptogenesis, which is defined as the sequence of events that converts a normal circuit into a hyperexcitable circuit and represents the time that occurs between the damaging event and the development of spontaneous seizure activity or the establishment of epilepsy. Epilepsy is the most common neurological disease in the world, characterized by the presence of seizures recurring without apparent provocation. Cannabidiol (CBD), a phytocannabinoid derived from the subspecies Cannabis sativa (CS), is the most studied active ingredient and is currently studied as a therapeutic strategy: it is an anticonvulsant mainly used in children with catastrophic epileptic syndromes and has also been reported to have anti-inflammatory and antioxidant effects, supporting it as a therapeutic strategy with neuroprotective potential. However, the mechanisms by which CBD exerts these effects are not entirely known, and the few studies on acute and chronic models in immature animals have provided contradictory results. Thus, it is difficult to evaluate the therapeutic profile of CBD, as well as the involvement of the endocannabinoid system in epileptogenesis in the immature brain. Therefore, this review focuses on the collection of scientific data in animal models, as well as information from clinical studies on the effects of cannabinoids on epileptogenesis and their anticonvulsant and adverse effects in early life.

The Effects of Cannabidiol, a Non-Intoxicating Compound of Cannabis, on the Cardiovascular System in Health and Disease

Cannabidiol (CBD) is a non-intoxicating and generally well-tolerated constituent of cannabis which exhibits potential beneficial properties in a wide range of diseases, including cardiovascular disorders. Due to its complex mechanism of action, CBD may affect the cardiovascular system in different ways. Thus, we reviewed the influence of CBD on this system in health and disease to determine the potential risk of cardiovascular side effects during CBD use for medical and wellness purposes and to elucidate its therapeutic potential in cardiovascular diseases. Administration of CBD to healthy volunteers or animals usually does not markedly affect hemodynamic parameters. Although CBD has been found to exhibit vasodilatory and antioxidant properties in hypertension, it has not affected blood pressure in hypertensive animals. Hypotensive action of CBD has been mainly revealed under stress conditions. Many positive effects of CBD have been observed in experimental models of heart diseases (myocardial infarction, cardiomyopathy, myocarditis), stroke, neonatal hypoxic ischemic encephalopathy, sepsis-related encephalitis, cardiovascular complications of diabetes, and ischemia/reperfusion injures of liver and kidneys. In these pathological conditions CBD decreased organ damage and dysfunction, oxidative and nitrative stress, inflammatory processes and apoptosis, among others. Nevertheless, further clinical research is needed to recommend the use of CBD in the treatment of cardiovascular diseases.

Cannabidiol and Sports Performance: a Narrative Review of Relevant Evidence and Recommendations for Future Research

Cannabidiol (CBD) is a non-intoxicating cannabinoid derived from Cannabis sativa. CBD initially drew scientific interest due to its anticonvulsant properties but increasing evidence of other therapeutic effects has attracted the attention of additional clinical and non-clinical populations, including athletes. Unlike the intoxicating cannabinoid, Δ9-tetrahydrocannabinol (Δ9-THC), CBD is no longer prohibited by the World Anti-Doping Agency and appears to be safe and well-tolerated in humans. It has also become readily available in many countries with the introduction of over-the-counter "nutraceutical" products. The aim of this narrative review was to explore various physiological and psychological effects of CBD that may be relevant to the sport and/or exercise context and to identify key areas for future research. As direct studies of CBD and sports performance are is currently lacking, evidence for this narrative review was sourced from preclinical studies and a limited number of clinical trials in non-athlete populations. Preclinical studies have observed robust anti-inflammatory, neuroprotective and analgesic effects of CBD in animal models. Preliminary preclinical evidence also suggests that CBD may protect against gastrointestinal damage associated with inflammation and promote healing of traumatic skeletal injuries. However, further research is required to confirm these observations. Early stage clinical studies suggest that CBD may be anxiolytic in "stress-inducing" situations and in individuals with anxiety disorders. While some case reports indicate that CBD improves sleep, robust evidence is currently lacking. Cognitive function and thermoregulation appear to be unaffected by CBD while effects on food intake, metabolic function, cardiovascular function, and infection require further study. CBD may exert a number of physiological, biochemical, and psychological effects with the potential to benefit athletes. However, well controlled, studies in athlete populations are required before definitive conclusions can be reached regarding the utility of CBD in supporting athletic performance.

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.

Medicinal Properties of Cannabinoids, Terpenes, and Flavonoids in Cannabis, and Benefits in Migraine, Headache, and Pain: An Update on Current Evidence and Cannabis Science

BACKGROUND

Comprehensive literature reviews of historical perspectives and evidence supporting cannabis/cannabinoids in the treatment of pain, including migraine and headache, with associated neurobiological mechanisms of pain modulation have been well described. Most of the existing literature reports on the cannabinoids Δ⁹ -tetrahydrocannabinol (THC) and cannabidiol (CBD), or cannabis in general. There are many cannabis strains that vary widely in the composition of cannabinoids, terpenes, flavonoids, and other compounds. These components work synergistically to produce wide variations in benefits, side effects, and strain characteristics. Knowledge of the individual medicinal properties of the cannabinoids, terpenes, and flavonoids is necessary to cross-breed strains to obtain optimal standardized synergistic compositions. This will enable targeting individual symptoms and/or diseases, including migraine, headache, and pain.

OBJECTIVE

Review the medical literature for the use of cannabis/cannabinoids in the treatment of migraine, headache, facial pain, and other chronic pain syndromes, and for supporting evidence of a potential role in combatting the opioid epidemic. Review the medical literature involving major and minor cannabinoids, primary and secondary terpenes, and flavonoids that underlie the synergistic entourage effects of cannabis. Summarize the individual medicinal benefits of these substances, including analgesic and anti-inflammatory properties.

CONCLUSION

There is accumulating evidence for various therapeutic benefits of cannabis/cannabinoids, especially in the treatment of pain, which may also apply to the treatment of migraine and headache. There is also supporting evidence that cannabis may assist in opioid detoxification and weaning, thus making it a potential weapon in battling the opioid epidemic. Cannabis science is a rapidly evolving medical sector and industry with increasingly regulated production standards. Further research is anticipated to optimize breeding of strain-specific synergistic ratios of cannabinoids, terpenes, and other phytochemicals for predictable user effects, characteristics, and improved symptom and disease-targeted therapies.

Effects of Cannabidiol on Diabetes Outcomes and Chronic Cerebral Hypoperfusion Comorbidities in Middle-Aged Rats

Diabetes and aging are risk factors for cognitive impairments after chronic cerebral hypoperfusion (CCH). Cannabidiol (CBD) is a phytocannabinoid present in the Cannabis sativa plant. It has beneficial effects on both cerebral ischemic diseases and diabetes. We have recently reported that diabetes interacted synergistically with aging to increase neuroinflammation and memory deficits in rats subjected to CCH. The present study investigated whether CBD would alleviate cognitive decline and affect markers of inflammation and neuroplasticity in the hippocampus in middle-aged diabetic rats submitted to CCH. Diabetes was induced in middle-aged rats (14 months old) by intravenous streptozotocin (SZT) administration. Thirty days later, the diabetic animals were subjected to sham or CCH surgeries and treated with CBD (10 mg/kg, once a day) during 30 days. Diabetes exacerbated cognitive deficits induced by CCH in middle-aged rats. Repeated CBD treatment decreased body weight in both sham- and CCH-operated animals. Cannabidiol improved memory performance and reduced hippocampal levels of inflammation markers (inducible nitric oxide synthase, ionized calcium-binding adapter molecule 1, glial fibrillary acidic protein, and arginase 1). Cannabidiol attenuated the decrease in hippocampal levels of brain-derived neurotrophic factor induced by CCH in diabetic animals, but it did not affect the levels of neuroplasticity markers (growth-associated protein-43 and synaptophysin) in middle-aged diabetic rats. These results suggest that the neuroprotective effects of CBD in middle-aged diabetic rats subjected to CCH are related to a reduction in neuroinflammation. However, they seemed to occur independently of hippocampal neuroplasticity changes.

Cannabidiol reduces lung injury induced by hypoxic-ischemic brain damage in newborn piglets

BackgroundBrain hypoxic-ischemic (HI) damage induces distant inflammatory lung damage in newborn pigs. We aimed to investigate the effects of cannabidiol (CBD) on lung damage in this scenario.MethodsNewborn piglets received intravenous vehicle, CBD, or CBD+WAY100635 (5-HT_1A receptor antagonist) after HI brain damage (carotid flow interruption and FiO₂ 0.10 for 30 min). Total lung compliance (TLC), oxygenation index (OI), and extravascular lung water content (EVLW) were monitored for 6 h. Histological damage, interleukin (IL)-1β concentration, and oxidative stress were assessed in brain and lung tissue. Total protein content was determined in bronchoalveolar lavage fluid (BALF).ResultsCBD prevented HI-induced deleterious effects on TLC and OI and reduced lung histological damage, modulating inflammation (decreased leukocyte infiltration and IL-1 concentration) and reducing protein content in BALF and EVLW. These effects were related to CBD-induced anti-inflammatory changes in the brain. HI did not increase oxidative stress in the lungs. In the lungs, WAY100635 blunted the beneficial effects of CBD on histological damage, IL-1 concentration, and EVLW.ConclusionsCBD reduced brain HI-induced distant lung damage, with 5-HT_1A receptor involvement in these effects. Whether the effects of CBD on the lungs were due to the anti-inflammatory effects on the brain or due to the direct effects on the lungs remains to be elucidated.

Cannabidiol reduces neuroinflammation and promotes neuroplasticity and functional recovery after brain ischemia

This study investigated the effects of cannabidiol (CBD), a non-psychotomimetic phytochemical present in Cannabis sativa, on the cognitive and emotional impairments induced by bilateral common carotid artery occlusion (BCCAO) in mice. Using a multi-tiered behavioral testing battery during 21days, we found that BCCAO mice exhibited long-lasting functional deficits reflected by increase in anxiety-like behavior (day 9), memory impairments (days 12-18) and despair-like behavior (day 21). Short-term CBD 10mg/kg treatment prevented the cognitive and emotional impairments, attenuated hippocampal neurodegeneration and white matter (WM) injury, and reduced glial response that were induced by BCCAO. In addition, ischemic mice treated with CBD exhibited an increase in the hippocampal brain derived neurotrophic factor (BDNF) protein levels. CBD also stimulated neurogenesis and promoted dendritic restructuring in the hippocampus of BCCAO animals. Collectively, the present results demonstrate that short-term CBD treatment results in global functional recovery in ischemic mice and impacts multiple and distinct targets involved in the pathophysiology of brain ischemic injury.

Cannabidiol: State of the art and new challenges for therapeutic applications

Over the past years, several lines of evidence support a therapeutic potential of Cannabis derivatives and in particular phytocannabinoids. Δ⁹-THC and cannabidiol (CBD) are the most abundant phytocannabinoids in Cannabis plants and therapeutic application for both compounds have been suggested. However, CBD is recently emerging as a therapeutic agent in numerous pathological conditions since devoid of the psychoactive side effects exhibited instead by Δ⁹-THC. In this review, we highlight the pharmacological activities of CBD, its cannabinoid receptor-dependent and -independent action, its biological effects focusing on immunomodulation, angiogenetic properties, and modulation of neuronal and cardiovascular function. Furthermore, the therapeutic potential of cannabidiol is also highlighted, in particular in nuerological diseases and cancer.

Recombinant human soluble thrombomodulin ameliorates cerebral ischemic injury through a high-mobility group box 1 inhibitory mechanism without hemorrhagic complications in mice

BACKGROUND

It has been reported that recombinant human soluble thrombomodulin (rhsTM) has a high-mobility group box (HMGB)1 inhibitory effect. Some investigators reported that HMGB1 is associated with ischemic stroke. However, there have been no previous studies to determine whether rhsTM can ameliorate cerebral ischemic injury through its HMGB1 inhibitory mechanism in ischemic stroke. We investigated the effects of rhsTM on cerebral ischemic injury in a 4-h middle cerebral artery occlusion (MCAO) murine model.

METHODS

rhsTM (1 or 5mg/kg, i.v.) was administered immediately after 4-h MCAO. Infarct volume, motor coordination, plasma HMGB1 level, and hemorrhage volume were evaluated 24h after 4-h MCAO.

RESULTS

The infarct volume (P<0.05) was reduced by rhsTM in mice subjected to 4-h MCAO in a dose-dependent manner. Moreover, rhsTM (5mg/kg) significantly improved motor coordination determined by the rotarod test (P<0.05), and significantly decreased plasma HMGB1 level compared with vehicle-treated controls (P<0.001). In addition, there was no difference in hemorrhage volume between vehicle-treated controls and the rhsTM treatment group.

CONCLUSIONS

This represents the first report that rhsTM ameliorates cerebral ischemic injury through an HMGB1 inhibitory mechanism without hemorrhagic complications in mice. Taken together, these observations indicate a palliative effect of rhsTM and suggest new therapeutic possibilities for treatment of ischemic stroke via inhibition of HMGB1.

Cannabinoids: Glutamatergic Transmission and Kynurenines

The endocannabinoid system (ECS) comprises a complex of receptors, enzymes, and endogenous agonists that are widely distributed in the central nervous system of mammals and participates in a considerable number of neuromodulatory functions, including neurotransmission, immunological control, and cell signaling. In turn, the kynurenine pathway (KP) is the most relevant metabolic route for tryptophan degradation to form the metabolic precursor NAD(+). Recent studies demonstrate that the control exerted by the pharmacological manipulation of the ECS on the glutamatergic system in the brain may offer key information not only on the development of psychiatric disorders like psychosis and schizophrenia-like symptoms, but it also may constitute a solid basis for the development of therapeutic strategies to combat excitotoxic events occurring in neurological disorders like Huntington's disease (HD). Part of the evidence pointing to the last approach is based on experimental protocols demonstrating the efficacy of cannabinoids to prevent the deleterious actions of the endogenous neurotoxin and KP metabolite quinolinic acid (QUIN). These findings intuitively raise the question about what is the precise role of the ECS in tryptophan metabolism through KP and vice versa. In this chapter, we will review basic concepts on the physiology of both the ECS and the KP to finally describe those recent findings combining the components of these two systems and hypothesize the future course that the research in this emerging field will take in the next years.

Cannabinoids and Epilepsy

Cannabis has been used for centuries to treat seizures. Recent anecdotal reports, accumulating animal model data, and mechanistic insights have raised interest in cannabis-based antiepileptic therapies. In this study, we review current understanding of the endocannabinoid system, characterize the pro- and anticonvulsive effects of cannabinoids [e.g., Δ9-tetrahydrocannabinol and cannabidiol (CBD)], and highlight scientific evidence from pre-clinical and clinical trials of cannabinoids in epilepsy. These studies suggest that CBD avoids the psychoactive effects of the endocannabinoid system to provide a well-tolerated, promising therapeutic for the treatment of seizures, while whole-plant cannabis can both contribute to and reduce seizures. Finally, we discuss results from a new multicenter, open-label study using CBD in a population with treatment-resistant epilepsy. In all, we seek to evaluate our current understanding of cannabinoids in epilepsy and guide future basic science and clinical studies.

Cannabinoids in experimental stroke: a systematic review and meta-analysis

Cannabinoids (CBs) show promise as neuroprotectants with some agents already licensed in humans for other conditions. We systematically reviewed CBs in preclinical stroke to guide further experimental protocols. We selected controlled studies assessing acute administration of CBs for experimental stroke, identified through systematic searches. Data were extracted on lesion volume, outcome and quality, and analyzed using random effect models. Results are expressed as standardized mean difference (SMD) with 95% confidence intervals (CIs). In all, 144 experiments (34 publications) assessed CBs on infarct volume in 1,473 animals. Cannabinoids reduced infarct volume in transient (SMD -1.41 (95% CI -1.71), -1.11) P<0.00001) and permanent (-1.67 (-2.08, -1.27), P<0.00001) ischemia and in all subclasses: endocannabinoids (-1.72 (-2.62, -0.82), P=0.0002), CB1/CB2 ligands (-1.75 (-2.19, -1.31), P<0.00001), CB2 ligands (-1.65 (-2.09, -1.22), P<0.00001), cannabidiol (-1.20 (-1.63, -0.77), P<0.00001), Δ(9)-tetrahydrocannabinol (-1.43 (-2.01, -0.86), P<0.00001), and HU-211 (-2.90 (-4.24, -1.56), P<0.0001). Early and late neuroscores significantly improved with CB use (-1.27 (-1.58, -0.95), P<0.00001; -1.63 (-2.64, -0.62), P<0.002 respectively) and there was no effect on survival. Statistical heterogeneity and publication bias was present, median study quality was 4 (range 1 to 6/8). Overall, CBs significantly reduced infarct volume and improve functional outcome in experimental stroke. Further studies in aged, female and larger animals, with other co-morbidities are required.

Targeting microglial activation in stroke therapy: pharmacological tools and gender effects

Ischemic stroke is caused by critical reductions in blood flow to brain or spinal cord. Microglia are the resident immune cells of the central nervous system, and they respond to stroke by assuming an activated phenotype that releases cytotoxic cytokines, reactive oxygen species, proteases, and other factors. This acute, innate immune response may be teleologically adapted to limit infection, but in stroke this response can exacerbate injury by further damaging or killing nearby neurons and other cell types, and by recruiting infiltration of circulating cytotoxic immune cells. The microglial response requires hours to days to fully develop, and this time interval presents a clinically accessible time window for initiating therapy. Because of redundancy in cytotoxic microglial responses, the most effective therapeutic approach may be to target the global gene expression changes involved in microglial activation. Several classes of drugs can do this, including histone deacetylase inhibitors, minocycline and other PARP inhibitors, corticosteroids, and inhibitors of TNFα and scavenger receptor signaling. Here we review the pre-clinical studies in which these drugs have been used to suppress microglial activation after stroke. We also review recent advances in the understanding of sex differences in the CNS inflammatory response, as these differences are likely to influence the efficacy of drugs targeting post-stroke brain inflammation.

Protective effect of cannabidiol against cadmium hepatotoxicity in rats

The protective effect of cannabidiol, the non-psychoactive component of Cannabis sativa, against liver toxicity induced by a single dose of cadmium chloride (6.5 mgkg(-1) i.p.) was investigated in rats. Cannabidiol treatment (5 mgkg(-1)/day, i.p.) was applied for five days starting three days before cadmium administration. Cannabidiol significantly reduced serum alanine aminotransferase, and suppressed hepatic lipid peroxidation, prevented the depletion of reduced glutathione and nitric oxide, and catalase activity, and attenuated the elevation of cadmium level in the liver tissue resulted from cadmium administration. Histopathological examination showed that cadmium-induced liver tissue injury was ameliorated by cannabidiol treatment. Immunohistochemical analysis revealed that cannabidiol significantly decreased the cadmium-induced expression of tumor necrosis factor-α, cyclooxygenase-2, nuclear factor-κB, caspase-3, and caspase-9, and increased the expression of endothelial nitric oxide synthase in liver tissue. It was concluded that cannabidiol may represent a potential option to protect the liver tissue from the detrimental effects of cadmium toxicity.

Nicotine-induced neuroprotection against ischemic injury involves activation of endocannabinoid system in rats

Nicotine has been reported to exert certain protective effect in the Parkinson's and Alzheimer's diseases. Whether it has a similar action in focal cerebral ischemia was unclear. In the present study, rats received either an injection of (-)-nicotine hydrogen tartrate salt (1.2 mg/kg, i.p.) or the vehicle 2 h before the 120 min middle cerebral artery occlusion. Neurological deficits and histological injury were assessed at 24 h after reperfusion. The content of endocannabinoids and the expression of cannabinoid receptor CB1 in brain tissues were determined at different time points after nicotine administration. Results showed that nicotine administration ameliorated neurological deficits and reduced infarct volume induced by cerebral ischemia in the rats. The neuroprotective effect was partially reversed by CB1 blockage. The content of the endocannabinoids N-arachidonylethanolamine and 2-arachidonoylglycerol, as well as the expression of cannabinoid receptor CB1 were up-regulated in brain tissues after nicotine delivery. These results suggest that endogenous cannabinoid system is involved in the nicotine-induced neuroprotection against transient focal cerebral ischemia.

Cannabidiol as an emergent therapeutic strategy for lessening the impact of inflammation on oxidative stress

Oxidative stress with reactive oxygen species generation is a key weapon in the arsenal of the immune system for fighting invading pathogens and initiating tissue repair. If excessive or unresolved, however, immune-related oxidative stress can initiate further increasing levels of oxidative stress that cause organ damage and dysfunction. Targeting oxidative stress in various diseases therapeutically has proven more problematic than first anticipated given the complexities and perversity of both the underlying disease and the immune response. However, growing evidence suggests that the endocannabinoid system, which includes the CB₁ and CB₂ G-protein-coupled receptors and their endogenous lipid ligands, may be an area that is ripe for therapeutic exploitation. In this context, the related nonpsychotropic cannabinoid cannabidiol, which may interact with the endocannabinoid system but has actions that are distinct, offers promise as a prototype for anti-inflammatory drug development. This review discusses recent studies suggesting that cannabidiol may have utility in treating a number of human diseases and disorders now known to involve activation of the immune system and associated oxidative stress, as a contributor to their etiology and progression. These include rheumatoid arthritis, types 1 and 2 diabetes, atherosclerosis, Alzheimer disease, hypertension, the metabolic syndrome, ischemia-reperfusion injury, depression, and neuropathic pain.

Therapeutic Potential of Non-Psychotropic Cannabidiol in Ischemic Stroke

Cannabis contains the psychoactive component delta⁹-tetrahydrocannabinol (delta⁹-THC), and the non-psychoactive components cannabidiol (CBD), cannabinol, and cannabigerol. It is well-known that delta⁹-THC and other cannabinoid CB₁ receptor agonists are neuroprotective during global and focal ischemic injury. Additionally, delta⁹-THC also mediates psychological effects through the activation of the CB₁ receptor in the central nervous system. In addition to the CB₁ receptor agonists, cannabis also contains therapeutically active components which are CB₁ receptor independent. Of the CB₁ receptor-independent cannabis, the most important is CBD. In the past five years, an increasing number of publications have focused on the discovery of the anti-inflammatory, anti-oxidant, and neuroprotective effects of CBD. In particular, CBD exerts positive pharmacological effects in ischemic stroke and other chronic diseases, including Parkinson’s disease, Alzheimer’s disease, and rheumatoid arthritis. The cerebroprotective action of CBD is CB₁ receptor-independent, long-lasting, and has potent anti-oxidant activity. Importantly, CBD use does not lead to tolerance. In this review, we will discuss the therapeutic possibility of CBD as a cerebroprotective agent, highlighting recent pharmacological advances, novel mechanisms, and therapeutic time window of CBD in ischemic stroke.