Serum resistin increases in a postprandial state during liquid meal challenge test in healthy human subjects

Endocannabinoid-mediated rescue of somatosensory cortex activity, plasticity and related behaviors following an early in life concussion

Due to the assumed plasticity of immature brain, early in life brain alterations are thought to lead to better recoveries in comparison to the mature brain. Despite clinical needs, how neuronal networks and associated behaviors are affected by early in life brain stresses, such as pediatric concussions, have been overlooked. Here we provide first evidence in mice that a single early in life concussion durably increases neuronal activity in the somatosensory cortex into adulthood, disrupting neuronal integration while the animal is performing sensory-related tasks. This represents a previously unappreciated clinically relevant mechanism for the impairment of sensory-related behavior performance. Furthermore, we demonstrate that pharmacological modulation of the endocannabinoid system a year post-concussion is well-suited to rescue neuronal activity and plasticity, and to normalize sensory-related behavioral performance, addressing the fundamental question of whether a treatment is still possible once post-concussive symptoms have developed, a time-window compatible with clinical treatment.

Goods and Bads of the Endocannabinoid System as a Therapeutic Target: Lessons Learned after 30 Years

The cannabis derivative marijuana is the most widely used recreational drug in the Western world and is consumed by an estimated 83 million individuals (∼3% of the world population). In recent years, there has been a marked transformation in society regarding the risk perception of cannabis, driven by its legalization and medical use in many states in the United States and worldwide. Compelling research evidence and the Food and Drug Administration cannabis-derived cannabidiol approval for severe childhood epilepsy have confirmed the large therapeutic potential of cannabidiol itself, Δ9-tetrahydrocannabinol and other plant-derived cannabinoids (phytocannabinoids). Of note, our body has a complex endocannabinoid system (ECS)-made of receptors, metabolic enzymes, and transporters-that is also regulated by phytocannabinoids. The first endocannabinoid to be discovered 30 years ago was anandamide (N-arachidonoyl-ethanolamine); since then, distinct elements of the ECS have been the target of drug design programs aimed at curing (or at least slowing down) a number of human diseases, both in the central nervous system and at the periphery. Here a critical review of our knowledge of the goods and bads of the ECS as a therapeutic target is presented to define the benefits of ECS-active phytocannabinoids and ECS-oriented synthetic drugs for human health. SIGNIFICANCE STATEMENT: The endocannabinoid system plays important roles virtually everywhere in our body and is either involved in mediating key processes of central and peripheral diseases or represents a therapeutic target for treatment. Therefore, understanding the structure, function, and pharmacology of the components of this complex system, and in particular of key receptors (like cannabinoid receptors 1 and 2) and metabolic enzymes (like fatty acid amide hydrolase and monoacylglycerol lipase), will advance our understanding of endocannabinoid signaling and activity at molecular, cellular, and system levels, providing new opportunities to treat patients.

A Complete Endocannabinoid Signaling System Modulates Synaptic Transmission between Human Induced Pluripotent Stem Cell-Derived Neurons

The endocannabinoid system (ECS) modulates synaptic function to regulate many aspects of neurophysiology. It adapts to environmental changes and is affected by disease. Thus, the ECS presents an important target for therapeutic development. Despite recent interest in cannabinoid-based treatments, few preclinical studies are conducted in human systems. Human induced pluripotent stem cells (hiPSCs) provide one possible solution to this issue. However, it is not known if these cells have a fully functional ECS. Here, we show that hiPSC-derived neuron/astrocyte cultures exhibit a complete ECS. Using Ca2+ imaging and a genetically encoded endocannabinoid sensor, we demonstrate that they not only respond to exogenously applied cannabinoids but also produce and metabolize endocannabinoids. Synaptically driven [Ca2+]i spiking activity was inhibited (EC50 = 48 ± 13 nM) by the efficacious agonist [R(+)-[2,3-dihydro-5-methyl-3-[(morpholinyl)methyl]pyrolol [1,2,3-de]-1,4-benzoxazin-yl]-(1-naphthalenyl)methanone mesylate] (Win 55,212-2) and by the endogenous ligand 2-arachidonoyl glycerol (2-AG; EC50 = 2.0 ± 0.6 µm). The effects of Win 55212-2 were blocked by a CB1 receptor-selective antagonist. Δ9-Tetrahydrocannabinol acted as a partial agonist, maximally inhibiting synaptic activity by 47 ± 14% (EC50 = 1.4 ± 1.9 µm). Carbachol stimulated 2-AG production in a manner that was independent of Ca2+ and blocked by selective inhibition of diacylglycerol lipase. 2-AG returned to basal levels via a process mediated by monoacylglycerol lipase as indicated by slowed recovery in cultures treated with 4-[Bis(1,3-benzodioxol-5-yl)hydroxymethyl]-1-piperidinecarboxylic acid 4-nitrophenyl ester (JZL 184). Win 55,212-2 markedly desensitized CB1 receptor function following a 1-day exposure, whereas desensitization was incomplete following 7-day treatment with JZL 184. This human cell culture model is well suited for functional analysis of the ECS and as a platform for drug development. SIGNIFICANCE STATEMENT: Despite known differences between the human response to cannabinoids and that of other species, an in vitro human model demonstrating a fully functional endocannabinoid system has not been described. Human induced pluripotent stem cells (hiPSCs) can be obtained from skin samples and then reprogrammed into neurons for use in basic research and drug screening. Here, we show that hiPSC-derived neuronal cultures exhibit a complete endocannabinoid system suitable for mechanistic studies and drug discovery.

Ketogenic Diet: An Effective Treatment Approach for Neurodegenerative Diseases

This review discusses the effects and mechanisms of a ketogenic diet on neurodegenerative diseases on the basis of available evidence. A ketogenic diet refers to a high-fat, mediumprotein, and low-carbohydrate diet that leads to a metabolic shift to ketosis. This review systematically summarizes the scientific literature supporting this effective treatment approach for neurodegenerative diseases, including effects on mitochondrial function, oxidative stress, neuronal apoptosis, neuroinflammation, and the microbiota-gut-brain axis. It also highlights the clinical evidence for the effects of the ketogenic diet in the treatment of Alzheimer's disease, Parkinson's disease, and motor neuron disease. Finally, it discusses the common adverse effects of ketogenic therapy. Although the complete mechanism of the ketogenic diet in the treatment of neurodegenerative diseases remains to be elucidated, its clinical efficacy has attracted many new followers. The ketogenic diet is a good candidate for adjuvant therapy, but its specific applicability depends on the type and the degree of the disease.

Proteomic profiling of postmortem prefrontal cortex tissue of suicide completers

Suicide is a leading cause of death worldwide, presenting a serious public health problem. We aimed to investigate the biological basis of suicide completion using proteomics on postmortem brain tissue. Thirty-six postmortem brain samples (23 suicide completers and 13 controls) were collected. We evaluated the proteomic profile in the prefrontal cortex (Broadmann area 9, 10) using tandem mass tag-based quantification with liquid chromatography-tandem mass spectrometry. Bioinformatics tools were used to elucidate the biological mechanisms related to suicide. Subgroup analysis was conducted to identify common differentially expressed proteins among clinically different groups. Of 9801 proteins identified, 295 were differentially expressed between groups. Suicide completion samples were mostly enriched in the endocannabinoid and apoptotic pathways (CAPNS1, CSNK2B, PTP4A2). Among the differentially expressed proteins, GSTT1 was identified as a potential biomarker among suicide completers with psychiatric disorders. Our findings suggest that the previously under-recognized endocannabinoid system and apoptotic processes are highly involved in suicide.

URB597 abrogates anxiogenic and depressive behaviors in the methamphetamine-withdrawal mice: Role of the cannabinoid receptor type 1, cannabinoid receptor type 2, and transient receptor potential vanilloid 1 channels

BACKGROUND

Methamphetamine is an addictive stimulant that possesses toxicity in the brain when taken repeatedly or at higher doses. Methamphetamine neurotoxicity is associated with numerous forms of mental impairment, including depression and anxiety. Evidence has also demonstrated that the endocannabinoid system is involved in the regulation of anxiety and depression.

AIMS

This study was designed to determine the involvement of the endocannabinoid system in anxiety- and depression-related behaviors in methamphetamine-withdrawal male NMRI mice.

METHODS

The elevated plus maze and forced swim test were used to assess the level of anxiety and depression.

RESULTS

We found that methamphetamine (30 mg/kg, intraperitoneal) evoked depressive- and anxiogenic-like effects at 3 days post-administration. Injection of URB597 (5-10 ng/mouse, intracerebroventricular), 10 min before the test, prevented the emotional deficits induced by methamphetamine withdrawal. Moreover, the cannabinoid receptor type 1 antagonist AM251 (1 μg/mouse) or cannabinoid receptor type 2 antagonist AM630 (5 and 10 μg/mouse) suppressed the antidepressant activity in the methamphetamine-withdrawal mice treated with URB597. The transient receptor potential vanilloid 1 antagonist capsazepine (25 μg/mouse) prevented while capsazepine (100 μg/mouse) potentiated the antidepressant efficacy in the methamphetamine-withdrawal mice treated with URB597. The higher dose of AM630 and two higher doses of capsazepine had antidepressant efficacy, by themselves. Furthermore, capsazepine (50 μg/mouse) increased locomotion in the methamphetamine-withdrawal mice treated with URB597.

CONCLUSIONS

The results suggest that URB597 has a potential for preventing methamphetamine withdrawal-evoked anxiety and depression. Cannabinoid type 1 receptors, cannabinoid type 2 receptors and transient receptor potential vanilloid 1 differently affect depression-related behaviors in methamphetamine-withdrawal mice treated with URB597.

New Insights in Cannabinoid Receptor Structure and Signaling

BACKGROUND

Cannabinoid has long been used for medicinal purposes. Cannabinoid signaling has been considered the therapeutic target for treating pain, addiction, obesity, inflammation, and other diseases. Recent studies have suggested that in addition to CB1 and CB2, there are non-CB1 and non-CB2 cannabinoid-related orphan GPCRs including GPR18, GPR55, and GPR119. In addition, CB1 and CB2 display allosteric binding and biased signaling, revealing correlations between biased signaling and functional outcomes. Interestingly, new investigations have indicated that CB1 is functionally present within the mitochondria of striated and heart muscles directly regulating intramitochondrial signaling and respiration.

CONCLUSION

In this review, we summarize the recent progress in cannabinoid-related orphan GPCRs, CB1/CB2 structure, Gi/Gs coupling, allosteric ligands and biased signaling, and mitochondria-localized CB1, and discuss the future promise of this research.

Opportunities for cannabis in supportive care in cancer

Cannabis has the potential to modulate some of the most common and debilitating symptoms of cancer and its treatments, including nausea and vomiting, loss of appetite, and pain. However, the dearth of scientific evidence for the effectiveness of cannabis in treating these symptoms in patients with cancer poses a challenge to clinicians in discussing this option with their patients. A review was performed using keywords related to cannabis and important symptoms of cancer and its treatments. Literature was qualitatively reviewed from preclinical models to clinical trials in the fields of cancer, human immunodeficiency virus (HIV), multiple sclerosis, inflammatory bowel disease, post-traumatic stress disorder (PTSD), and others, to prudently inform the use of cannabis in supportive and palliative care in cancer. There is a reasonable amount of evidence to consider cannabis for nausea and vomiting, loss of appetite, and pain as a supplement to first-line treatments. There is promising evidence to treat chemotherapy-induced peripheral neuropathy, gastrointestinal distress, and sleep disorders, but the literature is thus far too limited to recommend cannabis for these symptoms. Scant, yet more controversial, evidence exists in regard to cannabis for cancer- and treatment-related cognitive impairment, anxiety, depression, and fatigue. Adverse effects of cannabis are documented but tend to be mild. Cannabis has multifaceted potential bioactive benefits that appear to outweigh its risks in many situations. Further research is required to elucidate its mechanisms of action and efficacy and to optimize cannabis preparations and doses for specific populations affected by cancer.

What is the effect of a Mediterranean compared with a Fast Food meal on the exercise induced adipokine changes? A randomized cross-over clinical trial

Background

Adipose tissue-derived adipokines are pro-inflammatory cytokines involved in metabolic-related diseases and can be influenced by diet and exercise. We aimed to compare the effect of a Mediterranean (MdM) compared with Fast Food (FFM) meal on the exercise induced adipokines changes.

Methods

In a double blinded cross over trial, 46 participants were randomly assigned to one of two standardized iso-energy pre-exercise meals: FFM or MdM-type. Three hours after each meal, participants completed a treadmill exercise test (EC). Serum adiponectin, resistin, PAI-1, lipocalin-2/NGAL and adipsin were determined by Luminex magnetic bead immunoassay. Wilcoxon signed rank test compared changes before/after meal and before/after EC and a linear mixed model evaluated the effect of meals on the adipokine response to exercise, adjusted for confounders.

Results

Thirty-nine participants (mean age of 25, with a standard deviation of 5 years) completed the trial (56% females). For both interventions, a significant reduction of adipsin after each meal and a significant increase of lipocalin, PAI-1, adipsin and resistin, after exercise was observed. When exercise was preceded by a MdM meal a higher increase in adipsin levels was seen.

Conclusion

Acute exercise induced an increase of circulatory levels of adipsin, resistin, lipocalin and PAI-1, but not adiponectin. A pre-exercise Mediterranean meal potentiated the increase of adipsin after the exercise test, which possibly relates to the immune regulatory role of adipsin. These changes suggest a cross-talk between the immune and metabolic immediate response to exercise and its modulation by the pre-exercise diet composition.

Antimicrobial potential of endocannabinoid and endocannabinoid-like compounds against methicillin-resistant Staphylococcus aureus

Infections caused by antibiotic-resistant strains of Staphylococcus aureus have reached epidemic proportions globally. Staphylococcal biofilms are associated with increased antimicrobial resistance and are generally less affected by host immune factors. Therefore, there is an urgent need for novel agents that not only aim at multidrug-resistant pathogens, but also ones that will act as anti biofilms. In the present study, we investigated the antimicrobial activity of the endocannabinoid (EC) anandamide (AEA) and the endocannabinoid-like (EC-like), arachidonoyl serine (AraS) against methicillin resistant S. aureus strains (MRSA). We observed a strong inhibition of biofilm formation of all tested MRSA strains as well as a notable reduction of metabolic activity of pre-formed MRSA biofilms by both agents. Moreover, staphylococcal biofilm-associated virulence determinants such as hydrophobicity, cell aggregation and spreading ability were altered by AEA and AraS. In addition, the agents were able to modify bacterial membrane potential. Importantly, both compounds prevent biofilm formation by altering the surface of the cell without killing the bacteria. Therefore, we propose that EC and EC-like compounds may act as a natural line of defence against MRSA or other antibiotic resistant bacteria. Due to their anti biofilm action these agents could also be a promising alternative to antibiotic therapeutics against biofilm-associated MRSA infections.

Deficient endocannabinoid signaling in the central amygdala contributes to alcohol dependence-related anxiety-like behavior and excessive alcohol intake

Negative emotional states that are associated with excessive alcohol intake, particularly anxiety-like states, have been linked to opponent processes in the central nucleus of the amygdala (CeA), affecting stress-related transmitters and monoamines. This study extends these observations to include endocannabinoid signaling in alcohol-dependent animals. Rats and mice were exposed to chronic intermittent alcohol with vapor inhalation or liquid diet to induce dependence. In vivo microdialysis was used to estimate interstitial concentrations of endocannabinoids [N-arachidonoylethanolamine (anandamide; AEA) and 2-arachidonoylglycerol (2-AG)] and amino acids (glutamate and GABA) in rat CeA. Additionally, we evaluated the inhibition of endocannabinoids clearance enzymes [monoacylglycerol lipase (MAGL) and fatty acid amide hydrolase] on anxiety-like behavior and alcohol consumption in alcohol-dependent rats and mice. Results revealed that alcohol dependence produced decreases in baseline 2-AG dialysate levels and increases in baseline levels of glutamate and GABA. Acute alcohol abstinence induced an enhancement of these dependence-induced effects and the levels of 2-AG and GABA were restored upon alcohol re-exposure. Additional studies showed that the increased CeA 2-AG levels induced by restraint stress and alcohol self-administration were blunted in alcohol-dependent rats. Pharmacological studies in rats and mice showed that anxiety-like behavior and alcohol consumption were increased in alcohol-dependent animals, and these behavioral effects were attenuated mainly by MAGL inhibitors [MJN110 (10 and 20 mg/kg) in rats and JZL184 (1 and 3 mg/kg) in mice]. The present results suggest a key role for endocannabinoid signaling in motivational neuroadaptations during alcohol dependence, in which a deficiency in CeA 2-AG signaling in alcohol-dependent animals is linked to stress and excessive alcohol consumption.

Food for thought: how nutrition impacts cognition and emotion

More than one-third of American adults are obese and statistics are similar worldwide. Caloric intake and diet composition have large and lasting effects on cognition and emotion, especially during critical periods in development, but the neural mechanisms for these effects are not well understood. A clear understanding of the cognitive-emotional processes underpinning desires to over-consume foods can assist more effective prevention and treatments of obesity. This review addresses recent work linking dietary fat intake and omega-3 polyunsaturated fatty acid dietary imbalance with inflammation in developing, adult, and aged brains. Thus, early-life diet and exposure to stress can lead to cognitive dysfunction throughout life and there is potential for early nutritional interventions (e.g., with essential micronutrients) for preventing these deficits. Likewise, acute consumption of a high-fat diet primes the hippocampus to produce a potentiated neuroinflammatory response to a mild immune challenge, causing memory deficits. Low dietary intake of omega-3 polyunsaturated fatty acids can also contribute to depression through its effects on endocannabinoid and inflammatory pathways in specific brain regions leading to synaptic phagocytosis by microglia in the hippocampus, contributing to memory loss. However, encouragingly, consumption of fruits and vegetables high in polyphenolics can prevent and even reverse age-related cognitive deficits by lowering oxidative stress and inflammation. Understanding relationships between diet, cognition, and emotion is necessary to uncover mechanisms involved in and strategies to prevent or attenuate comorbid neurological conditions in obese individuals.

A novel crosstalk within the endocannabinoid system controls GABA transmission in the striatum

The N-palmitoylethanolamine (PEA) is an endogenous member of the endocannabinoid system (ECS) with several biological functions, including a neuromodulatory activity in the central nervous system. To shed light on the neuronal function of PEA, we investigated its involvement in the control of both excitatory and inhibitory transmission in the murine striatum, a brain region strongly modulated by the ECS. By means of electrophysiological recordings, we showed that PEA modulates inhibitory synaptic transmission, through activation of GPR55 receptors, promoting a transient increase of GABAergic spontaneous inhibitory postsynaptic current (sIPSC) frequency. The subsequently rundown effect on sIPSC frequency was secondary to the delayed stimulation of presynaptic cannabinoid CB1 receptors (CB1Rs) by the endocannabinoid 2-AG, whose synthesis was stimulated by PEA on postsynaptic neurons. Our results indicate that PEA, acting on GPR55, enhances GABA transmission in the striatum, and triggers a parallel synthesis of 2-AG at the postsynaptic site, that in turn acts in a retrograde manner to inhibit GABA release through the stimulation of presynaptic CB1Rs. This electrophysiological study identifies a previously unrecognized function of PEA and of GPR55, demonstrating that GABAergic transmission is under the control of this compound and revealing that PEA modulates the release of the endocannabinoid 2-AG.

Targeting anandamide metabolism rescues core and associated autistic-like symptoms in rats prenatally exposed to valproic acid

Autism spectrum disorders (ASD) are characterized by altered sociability, compromised communication and stereotyped/repetitive behaviors, for which no specific treatments are currently available. Prenatal exposure to valproic acid (VPA) is a known, although still underestimated, environmental risk factor for ASD. Altered endocannabinoid activity has been observed in autistic patients, and endocannabinoids are known to modulate behavioral traits that are typically affected in ASD. On this basis, we tested the hypothesis that changes in the endocannabinoid tone contribute to the altered phenotype induced by prenatal VPA exposure in rats, with focus on behavioral features that resemble the core and associated symptoms of ASD. In the course of development, VPA-exposed rats showed early deficits in social communication and discrimination, compromised sociability and social play behavior, stereotypies and increased anxiety, thus providing preclinical proof of the long-lasting deleterious effects induced by prenatal VPA exposure. At the neurochemical level, VPA-exposed rats displayed altered phosphorylation of CB1 cannabinoid receptors in different brain areas, associated with changes in anandamide metabolism from infancy to adulthood. Interestingly, enhancing anandamide signaling through inhibition of its degradation rescued the behavioral deficits displayed by VPA-exposed rats at infancy, adolescence and adulthood. This study therefore shows that abnormalities in anandamide activity may underlie the deleterious impact of environmental risk factors on ASD-relevant behaviors and that the endocannabinoid system may represent a therapeutic target for the core and associated symptoms displayed by autistic patients.

Modulation of cannabinoid signaling by hippocampal 5-HT4 serotonergic system in fear conditioning

Behavioral studies have suggested a key role for the cannabinoid system in the modulation of conditioned fear memory. Likewise, much of the literature has revealed that the serotonergic system affects Pavlovian fear conditioning and extinction. A high level of functional overlap between the serotonin and cannabinoid systems has also been reported. To clarify the interaction between the hippocampal serotonin (5-HT4) receptor and the cannabinoid CB1 receptor in the acquisition of fear memory, the effects of 5-HT4 agents, arachidonylcyclopropylamide (ACPA; CB1 receptor agonist), and the combined use of these drugs on fear learning were studied in a fear conditioning task in adult male NMRI mice. Pre-training intraperitoneal administration of ACPA (0.1 mg/kg) decreased the percentage of freezing time in both context- and tone-dependent fear conditions, suggesting impairment of the acquisition of fear memory. Pre-training, intra-hippocampal (CA1) microinjection of RS67333, a 5-HT4 receptor agonist, at doses of 0.1 and 0.2 or 0.2 µg/mouse impaired contextual and tone fear memory, respectively. A subthreshold dose of RS67333 (0.005 µg/mouse) did not alter the ACPA response in either condition. Moreover, intra-CA1 microinjection of RS23597 as a 5-HT4 receptor antagonist did not alter context-dependent fear memory acquisition, but it did impair tone-dependent fear memory acquisition. However, a subthreshold dose of the RS23597 (0.01 µg/mouse) potentiated ACPA-induced fear memory impairment in both conditions. Therefore, we suggest that the blockade of hippocampal 5-HT4 serotonergic system modulates cannabinoid signaling induced by the activation of CB1 receptors in conditioned fear.

Interactions between the endocannabinoid and nicotinic cholinergic systems: preclinical evidence and therapeutic perspectives

RATIONALE

Several lines of evidence suggest that endocannabinoid and nicotinic cholinergic systems are implicated in the regulation of different physiological processes, including reward, and in the neuropathological mechanisms of psychiatric diseases, such as addiction. A crosstalk between these two systems is substantiated by the overlapping distribution of cannabinoid and nicotinic acetylcholine receptors in many brain structures.

OBJECTIVE

We will review recent preclinical data showing how the endocannabinoid and nicotinic cholinergic systems interact bidirectionally at the level of the brain reward pathways, and how this interaction plays a key role in modulating nicotine and cannabinoid intake and dependence.

RESULTS

Many behavioral and neurochemical effects of nicotine that are related to its addictive potential are reduced by pharmacological blockade or genetic deletion of type-1 cannabinoid receptors, inhibition of endocannabinoid uptake or metabolic degradation, and activation of peroxisome proliferator-activated-receptor-α. On the other hand, cholinergic antagonists at α7 nicotinic acetylcholine receptors as well as endogenous negative allosteric modulators of these receptors are effective in blocking dependence-related effects of cannabinoids.

CONCLUSIONS

Pharmacological manipulation of the endocannabinoid system and endocannabinoid-like neuromodulators shows promise in the treatment of nicotine dependence and in relapse prevention. Likewise, drugs acting at nicotinic acetylcholine receptors might prove useful in the therapy of cannabinoid dependence. Research by Steven R. Goldberg has significantly contributed to the progress in this research field.

The endocannabinoid system and NGF are involved in the mechanism of action of resveratrol: a multi-target nutraceutical with therapeutic potential in neuropsychiatric disorders

RATIONALE

Resveratrol is a polyphenolic compound with antioxidant, anti-inflammatory, and neuroprotective effects. It has also shown antidepressant-like effects in the behavioral studies; however, its mechanism(s) of action merit further evaluation.

OBJECTIVES

The interaction between the nerve growth factor (NGF) and endocannabinoid system (eCBs) and their contribution to the antidepressant or emotional activity prompted us to evaluate their implications in the mechanism of action of resveratrol.

METHODS

After single and 4-week intraperitoneal (i.p.) once-daily injections of resveratrol (40, 80, and 100 mg/kg), amitriptyline (2.5, 5, and 10 mg/kg), or clonazepam (10, 20, and 40 mg/kg) into male Wistar rats, eCB and NGF contents were quantified in the brain regions implicated in the modulation of emotions by isotope-dilution liquid chromatography/mass spectrometry and Bio-Rad protein assay, respectively. In the case of any significant alteration of brain eCB or NGF level, the effect of pre-treatment with cannabinoid CB1 or CB2 receptor antagonist (AM251 or SR144528) was investigated.

RESULTS

Four-week treatment with resveratrol or amitriptyline resulted in a significant and sustained enhancement of NGF and eCB contents in dose-dependent and brain region-specific manner. Neither acute nor 4-week treatment with clonazepam affected brain eCB or NGF contents. Pre-treatment with AM251 (3 mg/kg), but not SR144528, prevented the enhancement of NGF protein levels. AM251 exhibited no effect by itself.

CONCLUSIONS

Resveratrol like the classical antidepressant, amitriptyline, affects brain NGF and eCB signaling under the regulatory drive of CB1 receptors.

Neural Plasticity in Multiple Sclerosis: The Functional and Molecular Background

Multiple sclerosis is an autoimmune neurodegenerative disorder resulting in motor dysfunction and cognitive decline. The inflammatory and neurodegenerative changes seen in the brains of MS patients lead to progressive disability and increasing brain atrophy. The most common type of MS is characterized by episodes of clinical exacerbations and remissions. This suggests the presence of compensating mechanisms for accumulating damage. Apart from the widely known repair mechanisms like remyelination, another important phenomenon is neuronal plasticity. Initially, neuroplasticity was connected with the developmental stages of life; however, there is now growing evidence confirming that structural and functional reorganization occurs throughout our lifetime. Several functional studies, utilizing such techniques as fMRI, TBS, or MRS, have provided valuable data about the presence of neuronal plasticity in MS patients. CNS ability to compensate for neuronal damage is most evident in RR-MS; however it has been shown that brain plasticity is also preserved in patients with substantial brain damage. Regardless of the numerous studies, the molecular background of neuronal plasticity in MS is still not well understood. Several factors, like IL-1β, BDNF, PDGF, or CB1Rs, have been implicated in functional recovery from the acute phase of MS and are thus considered as potential therapeutic targets.

Acute intake of a high-fructose diet alters the balance of adipokine concentrations and induces neutrophil influx in the liver

The postprandial state is a period of metabolic fluxes, biosynthesis and oxidative metabolism. A considerable amount is known about the inflammatory response to the chronic consumption of fructose, but little is known about its effects in the postprandial state. The aim of the present study was to investigate the inflammatory effects of a single meal containing fructose on healthy mice. Male BALB/c and LysM-eGFP mice at 12-14 weeks were divided into three groups: fasted, control (mice fed with a sucrose-containing diet) and fructose (mice fed with a fructose-containing diet). One, 2 or 4 h postprandial, the BALB/c mice were killed, and samples were collected. LysM-eGFP mice were submitted to intravital microscopy. The fed mice showed a low-grade inflammatory response apart from dietary composition, which was characterized by increased numbers of leukocytes and high serum concentrations of pentraxin 3, leptin and resistin. TNF-α and CCL2 concentrations rose in the liver after the meal. IL-6 concentration increased and IL-10 decreased in the adipose tissue of the fed mice. Mice fed with the fructose-containing diet showed an intensification of the inflammatory response. Furthermore, the adiponectin concentration dropped, and the liver influx of neutrophils increased after fructose intake. Overall, this study showed a rapid increase in the systemic and tissue-specific immune response after a balanced meal. The study also showed an increased neutrophil influx in liver associated with an imbalance of adipokine concentrations and an increase of cytokine in the liver and adipose tissue following a fructose-containing meal.

Cannabinoid receptors couple to NMDA receptors to reduce the production of NO and the mobilization of zinc induced by glutamate

AIMS

Overactivation of glutamate N-methyl-D-aspartate receptor (NMDAR) increases the cytosolic concentrations of calcium and zinc, which significantly contributes to neural death. Since cannabinoids prevent the NMDAR-mediated increase in cytosolic calcium, we investigated whether they also control the rise of potentially toxic free zinc ions, as well as the processes implicated in this phenomenon.

RESULTS

The cannabinoid receptors type 1 (CNR1) and NMDARs are cross-regulated in different regions of the nervous system. Cannabinoids abrogated the stimulation of the nitric oxide-zinc pathway by NMDAR, an effect that required the histidine triad nucleotide-binding protein 1 (HINT1). Conversely, NMDAR antagonism reduced the analgesia promoted by the CNR1 agonist WIN55,212-2 and impaired its capacity to internalize CNR1s. At the cell surface, CNR1s co-immunoprecipitated with the NR1 subunits of NMDARs, an association that diminished after the administration of NMDA in vivo or as a consequence of neuropathic overactivation of NMDARs, both situations in which cannabinoids do not control NMDAR activity. Under these circumstances, inhibition of protein kinase A (PKA) restored the association between CNR1s and NR1 subunits, and cannabinoids regained control over NMDAR activity. Notably, CNR1 and NR1 associated poorly in HINT1(-/-) mice, in which there was little cross-regulation between these receptors.

INNOVATION

The CNR1 can regulate NMDAR function when the receptor is coupled to HINT1. Thus, internalization of CNR1s drives the co-internalization of the NR1 subunits, neutralizing the overactivation of NMDARs.

CONCLUSION

Cannabinoids require the HINT1 protein to counteract the toxic effects of NMDAR-mediated NO production and zinc release. This study situates the HINT1 protein at the forefront of cannabinoid protection against NMDAR-mediated brain damage.

Convergent translational evidence of a role for anandamide in amygdala-mediated fear extinction, threat processing and stress-reactivity

Endocannabinoids are released 'on-demand' on the basis of physiological need, and can be pharmacologically augmented by inhibiting their catabolic degradation. The endocannabinoid anandamide is degraded by the catabolic enzyme fatty acid amide hydrolase (FAAH). Anandamide is implicated in the mediation of fear behaviors, including fear extinction, suggesting that selectively elevating brain anandamide could modulate plastic changes in fear. Here we first tested this hypothesis with preclinical experiments employing a novel, potent and selective FAAH inhibitor, AM3506 (5-(4-hydroxyphenyl)pentanesulfonyl fluoride). Systemic AM3506 administration before extinction decreased fear during a retrieval test in a mouse model of impaired extinction. AM3506 had no effects on fear in the absence of extinction training, or on various non-fear-related measures. Anandamide levels in the basolateral amygdala were increased by extinction training and augmented by systemic AM3506, whereas application of AM3506 to amygdala slices promoted long-term depression of inhibitory transmission, a form of synaptic plasticity linked to extinction. Further supporting the amygdala as effect-locus, the fear-reducing effects of systemic AM3506 were blocked by intra-amygdala infusion of a CB1 receptor antagonist and were fully recapitulated by intra-amygdala infusion of AM3506. On the basis of these preclinical findings, we hypothesized that variation in the human FAAH gene would predict individual differences in amygdala threat-processing and stress-coping traits. Consistent with this, carriers of a low-expressing FAAH variant (385A allele; rs324420) exhibited quicker habituation of amygdala reactivity to threat, and had lower scores on the personality trait of stress-reactivity. Our findings show that augmenting amygdala anandamide enables extinction-driven reductions in fear in mouse and may promote stress-coping in humans.

Frailty status and altered dynamics of circulating energy metabolism hormones after oral glucose in older women

OBJECTIVES

Frailty status is associated with altered glucose-insulin dynamics. Here, we sought to investigate whether alteration in the dynamics of other circulating energy metabolism hormones after oral glucose is associated with frailty status.

DESIGN

Substudy of older women in a prospective cohort.

SETTING

Baltimore, Maryland.

PARTICIPANTS

Seventy-three community-dwelling women aged 84-95 years without a diagnosis of diabetes who were enrolled in the Women's Health and Aging Study II.

MEASUREMENTS

We examined stimulus-response dynamics of free fatty acids (FFA), gut- (ghrelin,GLP-1) and adipocyte-derived hormones (leptin, adiponectin, resistin), growth hormone (GH), insulin-like growth factor 1 (IGF-1), and interleukin-6 (IL-6) at 0, 30, 60, 120, and 180-minutes after a 75-g glucose challenge according to frailty status (non-frail, pre-frail, or frail).

RESULTS

On average, frail women had higher fasting levels of glucose-raising hormones (FFA, resistin, GH, and IL-6) and lower fasting levels of glucose-lowering hormones (ghrelin, adiponectin, GLP-1 and IGF-1) versus non-frail women but these results were not statistically significant. Frail women also had higher fasting levels of leptin with relative adiposity compared to their counterparts, suggestive of leptin-resistance. Integrated area under the curve (AUC) values for each hormone followed similar trends by frailty status. After age and BMI adjustment, frail versus non-frail women were more likely to be in the lowest tertile of fasting ghrelin levels and 120-min ghrelin levels (both p<0.05) in logistic regression analyses. No large differences were found for other hormones in adjusted models.

CONCLUSIONS

Our findings suggest dysregulation of the orexigenic hormone ghrelin in the frailty syndrome. Further studies are needed to explore the role of ghrelin dysregulation in the clinical manifestation of frailty.

Mitochondrial CB₁ receptors regulate neuronal energy metabolism

The mammalian brain is one of the organs with the highest energy demands, and mitochondria are key determinants of its functions. Here we show that the type-1 cannabinoid receptor (CB(1)) is present at the membranes of mouse neuronal mitochondria (mtCB(1)), where it directly controls cellular respiration and energy production. Through activation of mtCB(1) receptors, exogenous cannabinoids and in situ endocannabinoids decreased cyclic AMP concentration, protein kinase A activity, complex I enzymatic activity and respiration in neuronal mitochondria. In addition, intracellular CB(1) receptors and mitochondrial mechanisms contributed to endocannabinoid-dependent depolarization-induced suppression of inhibition in the hippocampus. Thus, mtCB(1) receptors directly modulate neuronal energy metabolism, revealing a new mechanism of action of G protein-coupled receptor signaling in the brain.

The endocannabinoid system in the regulation of emotions throughout lifespan: a discussion on therapeutic perspectives

Alterations in emotion regulation processes may form the basis of psychopathologies. The endocannabinoid (eCB) system, composed of endogenous ligands, the enzymatic machinery in charge of their metabolism and the specific metabotropic receptors, has emerged as a major neuromodulatory system critically involved in the control of emotional homeostasis and stress responsiveness. Data from animal models indicate that the eCB system plays a key role in brain development, and is probably involved in the control of emotional states from early developmental stages. The present review summarizes the latest information on the role of the eCB system in emotionality and anxiety-related disorders throughout the lifespan. Putative therapeutic strategies based on the pharmacological modulation of this system will be discussed. Given the fact that the pharmacological modulation of the eCB system has recently arisen as a promising strategy in the management of anxiety and mood disorders, the potential efficacy of this pharmacological approach (i.e. blockers of the catabolic pathway) will be discussed, as well as pharmacological alternatives such as modulators of cannabinoid receptors other than the classical CB1 receptor, or administration of other plant-derived compounds (e.g. cannabidiol).

Thermogenesis and related metabolic targets in anti-diabetic therapy

Exercise, together with a low-energy diet, is the first-line treatment for type 2 diabetes type 2 diabetes . Exercise improves insulin sensitivity insulin sensitivity by increasing the number or function of muscle mitochondria mitochondria and the capacity for aerobic metabolism, all of which are low in many insulin-resistant subjects. Cannabinoid 1-receptor antagonists and β-adrenoceptor agonists improve insulin sensitivity in humans and promote fat oxidation in rodents independently of reduced food intake. Current drugs for the treatment of diabetes are not, however, noted for their ability to increase fat oxidation, although the thiazolidinediones increase the capacity for fat oxidation in skeletal muscle, whilst paradoxically increasing weight gain.There are a number of targets for anti-diabetic drugs that may improve insulin sensitivity insulin sensitivity by increasing the capacity for fat oxidation. Their mechanisms of action are linked, notably through AMP-activated protein kinase, adiponectin, and the sympathetic nervous system. If ligands for these targets have obvious acute thermogenic activity, it is often because they increase sympathetic activity. This promotes fuel mobilisation, as well as fuel oxidation. When thermogenesis thermogenesis is not obvious, researchers often argue that it has occurred by using the inappropriate device of treating animals for days or weeks until there is weight (mainly fat) loss and then expressing energy expenditure energy expenditure relative to body weight. In reality, thermogenesis may have occurred, but it is too small to detect, and this device distracts us from really appreciating why insulin sensitivity has improved. This is that by increasing fatty acid oxidation fatty acid oxidation more than fatty acid supply, drugs lower the concentrations of fatty acid metabolites that cause insulin resistance. Insulin sensitivity improves long before any anti-obesity effect can be detected.

Serum pattern of circulating adipokines throughout the physiological menstrual cycle

This study investigated the serum levels of resistin, adiponectin and leptin during the physiological menstrual cycle. Sixteen women (age: 19-30 years; body mass index: 19.46-24.9) with regular menstrual cycles participated. Fasting blood samples were collected on alternate days throughout a full menstrual cycle. Mean resistin concentrations were slightly higher during the luteal phase (5.30+/-0.23 ng/ml) compared to the follicular (4.68+/-0.07 ng/ml) and midcycle (4.86+/-0.09 ng/ml) phases (p=0.032). Mean leptin concentrations during the follicular phase (18.14+/-0.28 ng/ml) were significantly lower compared to the midcycle (21.79+/-0.29 ng/ml, p=0.006) and luteal phases (23.75+/-0.64 ng/ml, p<0.001). The variation of adiponectin concentrations throughout the menstrual cycle was not significant. According to the results, circulating resistin, likewise leptin concentrations vary significantly during the physiological menstrual cycle presenting with higher values during the luteal phase. This pattern, although its physiological importance is not clear, suggests that resistin, likewise to leptin, may have a role in the regulation of cyclic female reproductive functions. The stable adiponectin concentrations throughout the menstrual cycle indicate that this adipokine probably does not play a considerable role in female reproductive functions.

Roles of the endocannabinoid system in learning and memory

The endocannabinoid system (ECS) plays a central role in the regulation of learning and memory processes. The fine-tuned regulation of neural transmission by the system is likely to be the mechanism underlying this important function. In this chapter, we review the data in the literature showing the direct involvement of the physiological activation of cannabinoid receptors in the modulation of different forms of learning and memory. When possible, we also address the likely mechanisms of this involvement. Finally, given the apparent special role of the ECS in the extinction of fear, we propose a reasonable model to assess how neuronal networks could be influenced by the endocannabinoids in these processes. Overall, the data reviewed indicate that, despite the enormous progress of recent years, much is still to be done to fully elucidate the mechanisms of the ECS influence on learning and memory processes.

Effect of raisin consumption on oxidative stress and inflammation in obesity

AIM

Oxidative stress can initiate increased inflammation that elevates risk for cardiovascular disease. The objective of this study was to determine the effects of daily consumption of raisins on markers of oxidative stress, inflammation and endothelial activation in response to an acute high-fat meal in overweight individuals.

METHODS

Seventeen overweight men and women consumed 90 g raisins or isocaloric placebo (264 kcal/day) for 14 days in a randomized, crossover design while following a low-flavonoid diet. The oxidative [urinary 8-iso-prostaglandin-F(2alpha) (8-epi PGF(2alpha)) and serum oxygen radical absorbance capacity (ORAC)], inflammatory (serum C-reactive protein and interleukin-6), endothelial (serum soluble intercellular adhesion molecule-1 and soluble vascular cell adhesion molecule-1, sVCAM-1) and metabolic [free fatty acids (FFAs), triacylglycerol, glucose and insulin] response to four high-fat (53%) meals was tested pre- and postintervention.

RESULTS

Urinary 8-epi PGF(2alpha) decreased (-22%) and fasting ORAC increased (+3%) after both interventions combined. Fasting protein-free ORAC was modestly (+3.5%) higher during the raisin than the placebo intervention. Neither the meals nor the raisins consistently induced fasted markers of inflammation or endothelial dysfunction. Gender influenced postprandial metabolic responses in that males responded with higher serum FFAs, sVCAM-1 and glucose compared with females.

CONCLUSIONS

Serum antioxidant capacity was modestly increased by daily raisin consumption, but this did not alter fasted or postprandial inflammatory response in these relatively healthy but overweight individuals. Providing all food in regular pattern reduced measures of oxidative stress.

Endocannabinoids modulate encoding of sequential memory in the rat hippocampus

RATIONALE

This report investigated the role of endocannabinoids in the encoding of task-relevant information by ensembles of hippocampal neurons under conditions in which the CB1 receptor antagonist, rimonabant, was administered during performance of a short-term memory delayed non-match to sample (DNMS) task in rats.

OBJECTIVE

The influence of endocannabinoids on the encoding of task relevant information was determined via examination of the firing patterns of ensembles of CA1/CA3 hippocampal neurons during individual trials while rats performed a DNMS task.

MATERIALS AND METHODS

Multivariate discriminant analysis of the firing patterns of ensembles of hippocampal neurons was used to extract trial-specific codes for task-relevant information under different types of trial sequences.

RESULTS

It was discovered that rimonabant blocked an inherent hippocampal memory encoding bias used by all animals. This bias was characterized as the preferential encoding of sample information on individual trials based on the similarity (i.e., same or different) and duration of the delay in the preceding trial.

CONCLUSIONS

The results indicate that endocannabinoids are a major influence on the strategic encoding biases of hippocampal ensembles and that pharmacological blockade of CB1 receptors facilitated performance by eliminating such influences.

Plasma resistin levels and risk of myocardial infarction and ischemic stroke

CONTEXT

Resistin is a hormone that has been linked to insulin resistance, inflammatory processes, and coronary heart disease in case-control studies; however, prospective data on the association between plasma resistin levels and future risk of cardiovascular disease are lacking.

OBJECTIVE

The objective of the study was to investigate the association between plasma resistin levels and risk of future myocardial infarction (MI) and ischemic stroke (IS) in a large prospective cohort.

METHODS

We investigated the association between plasma resistin levels and risk of MI and IS in a case-cohort design among 26,490 middle-aged subjects from the European Investigation into Cancer and Nutrition-Potsdam Study without history of MI or stroke at time of blood draw. Plasma resistin levels were measured in baseline blood samples of 139 individuals who developed MI, 97 who developed IS, and 817 individuals who remained free of cardiovascular events during a mean follow-up of 6 yr.

RESULTS

After multivariable adjustment for established cardiovascular risk factors including C-reactive protein, individuals in the highest compared with the lowest quartile of plasma resistin levels had a significantly increased risk of MI (relative risk 2.09; 95% confidence interval 1.01-4.31; P for trend = 0.01). In contrast, plasma resistin levels were not significantly associated with risk of IS (relative risk 0.94; 95% confidence interval 0.51-1.73; P for trend = 0.88).

CONCLUSION

Our data suggest that high plasma resistin levels are associated with an increased risk of MI but not with risk of IS. Further studies are needed to evaluate the predictive value of plasma resistin levels for cardiovascular disease.

Activation of CB1 specifically located on GABAergic interneurons inhibits LTD in the lateral amygdala

Previously, we found that in the lateral amygdala (LA) of the mouse, WIN55,212-2 decreases both glutamatergic and GABAergic synaptic transmission via activation of the cannabinoid receptor type 1 (CB1), yet produces an overall reduction of neuronal excitability. This suggests that the effects on excitatory transmission override those on inhibitory transmission. Here we show that CB1 activation by WIN55,212-2 and Delta(9)-THC inhibits long-term depression (LTD) of basal synaptic transmission in the LA, induced by low-frequency stimulation (LFS; 900 pulses/1 Hz). The CB1 agonist WIN55,212-2 blocked LTD via G(i/o) proteins, activation of inwardly rectifying K+ channels (K(ir)s), inhibition of the adenylate cyclase-protein kinase A (PKA) pathway, and PKA-dependent inhibition of voltage-gated N-type Ca2+ channels (N-type VGCCs). Interestingly, WIN55,212-2 effects on LTD were abolished in CB1 knock-out mice (CB1-KO), and in conditional mutants lacking CB1 expression only in GABAergic interneurons, but were still present in mutants lacking CB1 in principal forebrain neurons. LTD induction per se was unaffected by the CB1 antagonist SR141716A and was normally expressed in CB1-KO as well as in both conditional CB1 mutants. Our data demonstrate that activation of CB1 specifically located on GABAergic interneurons inhibits LTD in the LA. These findings suggest that CB1 expressed on either glutamatergic or GABAergic neurons play a differential role in the control of synaptic transmission and plasticity.

Extinction learning: neurological features, therapeutic applications and the effect of aging

Extinction learning consists of the usually gradual inhibition of the retrieval of a previously learned response or behavior. It is widely used for the treatment of syndromes of learned fear, such as phobias and post-traumatic stress disorder. It relies on well-identified molecular processes in the hippocampus, basolateral amygdala, ventromedial prefrontal cortex (vmPFC) and entorhinal cortex. In humans, thickness of the orbital cortex, vmPFC and the anterior cingulate cortex correlates with the capacity to extinguish. The three regions are functionally inter-related (see below). The development of learned fear syndromes in humans is viewed by many as being due to a deficit of extinction, and so of the capacity to deal with fear. Blockade of NMDA receptors, inhibition of protein synthesis in the vmPFC or blockade of protein synthesis or of various molecular signaling cascades in the hippocampus, amygdala or entorhinal cortex impairs extinction. d-cycloserine, a partial agonist at NMDA receptors, enhances extinction in animals and humans and may help extinction to exert its therapeutic effect. Cannabinoids also enhance extinction, acting through CB1 receptors, but their therapeutic use is not warranted.

Serum resistin is reduced by glucose and meal loading in healthy human subjects

Resistin is an adipokine that induces insulin resistance in mice; serum concentrations are decreased by fasting and increased by feeding. Adiponectin, another adipokine, improves insulin sensitivity. The aims of this study were to determine the effects of glucose and meal loading on serum resistin and total and high-molecular weight (HMW) adiponectin in humans and to explore potential determinants of fasting serum resistin and of changes in resistin. Serum resistin and total and HMW adiponectin were measured by enzyme-linked immunosorbent assay in young, lean, nondiabetic subjects during 75-g oral glucose tolerance test (OGTT) and meal tolerance test (MTT). Resistin single nucleotide polymorphism (SNP) -420 was typed. Serum resistin was decreased at 60 and 120 minutes during OGTT compared with baseline (n = 36, 1-way repeated-measures analysis of variance, P < .0001; Scheffe, P = .0457 and P < .0001, respectively). Serum resistin was also reduced at 240 minutes during MTT (n = 33, 1-way repeated measures analysis of variance, P < .0001; Scheffe, P = .0002). Multiple regression analysis adjusted for age, sex, and body mass index revealed that the reductions in serum resistin were dependent on baseline resistin levels. Subjects with greater baseline concentrations of resistin experienced more pronounced declines in resistin (OGTT, unstandardized regression coefficient (beta) = -0.19, P = .0005; MTT, beta = -0.63, P < .0001). Serum total and HMW adiponectin was unchanged. Fasting serum resistin was positively correlated with the G allele number of SNP -420 (beta = 7.70, P = .01) and white blood cell count (beta = 0.007, P = .0001) adjusted for age, sex, and body mass index. Therefore, in young, lean, nondiabetic humans, serum resistin was reduced by glucose and meal loading; the reduction in resistin was greater in subjects with higher fasting resistin. Fasting resistin was correlated with SNP -420 and white blood cell count.

Within-subject variation of plasma resistin levels over a 1-year period

BACKGROUND

Resistin, a recently discovered hormone, is purportedly involved in metabolic and inflammatory processes in humans and may thus be an important marker to assess disease risk in large-scale epidemiological studies.

METHODS

We assessed the reliability of human resistin levels in 63 men and 51 women aged 35-67 years with repeated measurements of resistin over a period of 1 year. Student's paired t-test was used to compare resistin concentrations at baseline and 1 year later. Intraclass correlation coefficients (ICCs) were calculated by analysis of variance.

RESULTS

There was no significant difference between resistin concentrations at baseline and after 1 year for both sexes combined or when analyzed separately for men and women. The ICCs were 0.70 (95% CI 0.59-0.78) for both sexes combined, 0.75 (95% CI 0.62-0.84) for men, and 0.66 (95% CI 0.47-0.79) for women. Resistin levels were not significantly related to age, body mass index, waist-to-hip ratio, sex, or fasting status.

CONCLUSIONS

Individual blood resistin concentrations did not significantly change over a period of 1 year, but showed a high degree of reliability. Our findings suggest that a single resistin measurement may be sufficient for risk assessment in epidemiological studies.

Endocannabinoids and traumatic brain injury

In response to traumatic brain injury, there is local and transient accumulation of 2-AG at the site of injury, peaking at 4 h and sustained up to at least 24 h. Neuroprotection exerted by exogenous 2-AG suggests that the formation of 2-AG may serve as a molecular regulator of pathophysiological events, attenuating the brain damage. Inhibition of this protective effect by SR-141716A, a CB(1) cannabinoid receptor antagonist, and the lack of effect of 2-AG in CB(1) knockout mice suggest that 2-AG and the CB(1) receptor may be important in the pathophysiology of traumatic brain injury. 2-AG exerts its neuroprotective effect after traumatic brain injury, at least in part, by inhibition of NF-kappaB transactivation. 2-AG also inhibits, at an early stage (2-4 h), the expression of the main proinflammatory cytokines, TNF-alpha, IL-6, and IL-1beta, and is accompanied by reduction of BBB permeability. Moreover, the CB(1), CB(2), and TRVP1 receptors are expressed on microvascular endothelial cells, and their activation by 2-AG counteracts endothelin (ET-1)-induced cerebral microvascular responses (namely, Ca(2+) mobilization and cytoskeleton rearrangement). This suggests that the functional interaction between 2-AG and ET-1 may provide a potential alternative pathway for abrogating ET-1-inducible vasoconstriction after brain injury and play a role in the neuroprotective effects exerted by 2-AG, as a potent vasodilator.

CB1 receptor antagonist AVE1625 affects primarily metabolic parameters independently of reduced food intake in Wistar rats

The objective of the present study was to investigate in fed Wistar rats whether the cannabinoid-1 (CB1) receptor antagonist AVE1625 causes primary effects on metabolic blood and tissue parameters as well as metabolic rate, which are independent of reduced caloric intake. After single administration to rats postprandially, AVE1625 caused a slight dose-dependent increase in basal lipolysis. Six hours after single administration, liver glycogen content was dose-dependently reduced to approximately 60% of that of untreated controls. These findings demonstrate a primary acute effect of AVE1625 on induction of 1) lipolysis from fat tissue (increased FFA) and 2) glycogenolysis from the liver (reduced hepatic glycogen). Measured by indirect calorimetry, AVE1625 caused an immediate increase in total energy expenditure, a long-lasting increase of fat oxidation, and a transient increase of glucose oxidation, which were consistent with the acute findings on metabolic blood and tissue parameters. We conclude that, in addition to the well-investigated effects of CB1 receptor antagonists to reduce caloric intake and subsequently body weight, this pharmacological approach is additionally linked to inherently increased lipid oxidation. This oxidation is driven by persistently increased lipolysis from fat tissues, independently of reduced caloric intake, and might significantly contribute to the weight-reducing effect.

Cannabinoids and neuroprotection in basal ganglia disorders

Cannabinoids have been proposed as clinically promising neuroprotective molecules, as they are capable to reduce excitotoxicity, calcium influx, and oxidative injury. They are also able to decrease inflammation by acting on glial processes that regulate neuronal survival and to restore blood supply to injured area by reducing the vasoconstriction produced by several endothelium-derived factors. Through one or more of these processes, cannabinoids may provide neuroprotection in different neurodegenerative disorders including Parkinson's disease and Huntington's chorea, two chronic diseases that are originated as a consequence of the degeneration of specific nuclei of basal ganglia, resulting in a deterioration of the control of movement. Both diseases have been still scarcely explored at the clinical level for a possible application of cannabinoids to delay the progressive degeneration of the basal ganglia. However, the preclinical evidence seems to be solid and promising. There are two key mechanisms involved in the neuroprotection by cannabinoids in experimental models of these two disorders: first, a cannabinoid receptor-independent mechanism aimed at producing a decrease in the oxidative injury and second, an induction/upregulation of cannabinoid CB2 receptors, mainly in reactive microglia, that is capable to regulate the influence of these glial cells on neuronal homeostasis. Considering the relevance of these preclinical data and the lack of efficient neuroprotective strategies in both disorders, we urge the development of further studies that allow that the promising expectatives generated for these molecules progress from the present preclinical evidence till a real clinical application.