Cannabinoids, eating behaviour, and energy homeostasis

Vaporized Δ9-THC in utero results in reduced birthweight, increased locomotion, and altered wake-cycle activity dependent on dose, sex, and diet in the offspring

AIMS

Preclinical studies have found that chronic ∆9-tetrahydrocannabinol (THC) treatment is directly associated with weight gain when introduced during adolescence and adulthood, but the effect of prenatal THC is unclear. Clinical studies have demonstrated prenatal exposure to THC is a prospective predictor of increased health risks associated with obesity. Our study aims to examine prenatal THC impact on obesity risks in males and females throughout adolescence using a clinically relevant inhalation model.

METHODS

Pregnant rats were exposed to one of the following from gestational day 2 through birth: 10 mg THC, 40 mg THC, or air. Daily 10-min inhalations were conducted in each animal from 0900 to 1200. Offspring from each treatment group were given either a high-fat diet (HFD) or a normal diet (ND). Food and bodyweights were collected daily, while circadian activity, locomotion, and exercise were measured periodically (PND 21-60). Pregnancy weight gain and birth weight were collected to determine early-life developmental effects.

RESULTS

Rats prenatally treated with low-dose THC (LDTHC) generally had lower dark-cycle activity compared with control counterparts, but this altered activity was not observed at the higher dose of THC (HDTHC). In terms of open-field activity, THC doses displayed a general increase in locomotion. In addition, the LDTHC male rats in the ND showed significantly greater exploratory behavior. Prenatal THC had dose-dependent effects on maternal weight gain and birth weight.

CONCLUSIONS

Overall, our findings indicate there are some activity-related and developmental effects of prenatal THC, which may be related to obesity risks later in life.

Pharmacophore-based virtual screening from phytocannabinoids as antagonist r-CB1

Search for new pharmacological alternatives for obesity is based on the design and development of compounds that can aid in weight loss so that they can be used safely and effectively over a long period while maintaining their function. The endocannabinoid system is related to obesity by increasing orexigenic signals and reducing satiety signals. Cannabis sativa is a medicinal plant of polypharmaceutical potential that has been widely studied for various medicinal purposes. The in silico evaluation of their natural cannabinoids (also called phytocannabinoids) for anti-obesity purpose stems from the existence of synthetic cannabinoid compounds that have already presented this result, but which did not guarantee patient safety. In order to find new molecules from C. sativa phytocannabinoids, with the potential to interact peripherally with the pharmacological target cannabinoid receptor 1, a pharmacophore-based virtual screening was performed, including the evaluation of physicochemical, pharmacokinetic, toxicological predictions and molecular docking. The results obtained from the ZINC¹² database pointed to Zinc 69 (ZINC33053402) and Zinc 70 (ZINC19084698) molecules as promising anti-obesity agents. Molecular dynamics (MD) studies disclose that both complexes were stable by analyzing the RMSD (root mean square deviation) values, and the binding free energy values demonstrate that the selected structures can interact and inhibit their catalytic activity.

Effects of Δ9-Tetrahydrocannibinol (THC) on Obesity at Different Stages of Life: A Literature Review

The Cannabis sativa plant has historically been used for both recreational and medical purposes. With the recent surge in recreational use of cannabis among adolescents and adults in particular, there is an increased obligation to determine the short- and long-term effects that consuming this plant may have on several aspects of the human psyche and body. The goal of this article was to examine the negative effects of obesity, and how the use of Δ9-tetrahydrocannibinol (THC) or cannabidiol (CBD) can impact rates of this global pandemic at different timepoints of life. Conflicting studies have been reported between adult and adolescents, as there are reports of THC use leading to increased weight due to elevated appetite and consumption of food, while others observed a decrease in overall body weight due to the regulation of omega-6/omega-3 endocannabinoid precursors and a decrease in energy expenditure. Studies supported a positive correlation between prenatal cannabis use and obesity rates in the children as they matured. The data did not indicate a direct connection between prenatal THC levels in cannabis and obesity rates, but that this development may occur due to prenatal THC consumption leading to low birthweight, and subsequent obesity. There are few studies using animal models that directly measure the effects that prenatal THC administration on obesity risks among offspring. Thus, this is a critical area for future studies using a developmental framework to examine potential changes in risk across development.

Roles of Endocannabinoids and Endocannabinoid-like Molecules in Energy Homeostasis and Metabolic Regulation: A Nutritional Perspective

The endocannabinoid system is involved in signal transduction in mammals. It comprises principally G protein-coupled cannabinoid receptors and their endogenous agonists, called endocannabinoids, as well as the enzymes and transporters responsible for the metabolism of endocannabinoids. Two arachidonic acid-containing lipid molecules, arachidonoylethanolamide (anandamide) and 2-arachidonoylglycerol, function as endocannabinoids. N-acylethanolamines and monoacylglycerols, in which the arachidonic acid chain is replaced with a saturated or monounsaturated fatty acid, are not directly involved in the endocannabinoid system but exhibit agonistic activities for other receptors. These endocannabinoid-like molecules include palmitoylethanolamide, oleoylethanolamide (OEA), and 2-oleoylglycerol. Endocannabinoids stimulate feeding behavior and the anabolism of lipids and glucose, while OEA suppresses appetite. Both central and peripheral systems are included in these nutritional and metabolic contexts. Therefore, they have potential in the treatment and prevention of obesity. We outline the structure, metabolism, and biological activities of endocannabinoids and related molecules, and focus on their involvement in energy homeostasis and metabolic regulation. Expected final online publication date for the Annual Review of Nutrition, Volume 41 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Metabonomic Study on the Plasma of High-Fat Diet-Induced Dyslipidemia Rats Treated with Ge Gen Qin Lian Decoction by Ultrahigh-Performance Liquid Chromatography-Mass Spectrometry

Gegen Qinlian decoction (GGQLD) has a definite effect on T2DM in clinic, and it has the effect of lowering blood sugar, improving insulin resistance, and improving the blood lipid level of rats with dyslipidemia, but the intervention mechanism of GGQLD on dyslipidemia has not been clarified. The changes in endogenous metabolites in the plasma of high-fat diet-induced dyslipidemia rats treated with Ge Gen Qin Lian Decoction (GGQLD) were studied to elucidate the therapeutic effects and mechanism of action of GGQLD in dyslipidemia. Based on ultrahigh-performance liquid chromatography coupled with quadrupole-time-of-flight tandem mass spectrometry (UHPLC-Q-TOF-MS), the metabolic profiles of rat serum samples were collected. The rat model of dyslipidemia was induced by a 60% fat-fed high-fat diet. After feeding the rats with a high-fat diet for 4 weeks, dyslipidemia appeared. After 5 weeks of GGQLD (14.85 g kg⁻¹) administration, the metabonomics of rats' plasma samples in the normal group, model group, and administration group were analyzed. Mass profiler professional (MPP), SIMCA-P 14.1, and Graphpad prism 6.0 software were used combined with METLIN biological database and human metabolite database HMDB to screen and identify endogenous biomarkers. Metaboanalyst 4.0 software was used by combining with HMDB and KEGG databases; the enrichment and metabolic pathway of biomarkers were analyzed to explore the metabolic mechanism of dyslipidemia rats induced by high-fat diet and the intervention mechanism of Gegen Qinlian decoction. After 5 weeks of administration of GGQLD, the levels of serum TC and TG were significantly decreased (P < 0.05, P < 0.01), while HDL-C and LDL-C were not significantly affected. After administration, the food intake of rats in the administration group decreased gradually, and the change trend of body weight gradually slowed down. The metabonomics of rat plasma samples results showed that 23 potential biomarkers including α-linolenic acid, arachidonic acid, and lysophosphatidylcholine were significantly changed in positive ion mode. Studies have shown that GGQLD has a significant lipid-lowering effect on dyslipidemia rats induced by a high-fat diet, and its preventive mechanism is related to tryptophan metabolism, fatty acid biosynthesis, α-linolenic acid metabolism, arachidonic acid, and glycerophosphatidyl metabolism pathway.

Salivary endocannabinoids as mediators in the relationship between omega-6 and omega-3 fatty acid ratio intake from highly-processed foods and anthropometric markers of health in women

Data suggest that a high ω6 to ω3 ratio (ω6:ω3) contributes to obesity. Highly processed foods are a common source of high ω6:ω3 and have also been associated with increased cardiovascular risk. We hypothesised that salivary endocannabinoids (eCBs) act as a mediator between ω6:ω3 from highly processed foods and anthropometric markers of cardiovascular risk. Finally, we explored sex differences on these parameters. Participants filled a self-report intake frequency inventory. Body measurements were registered, and fasted saliva was collected and analysed using LC/MRM. Overweight subjects consuming more highly processed foods, but not those consuming more whole foods, presented an increased ω6:ω3 and salivary eCB levels. Also, the ω6:ω3 ratio in participants consuming highly processed but not whole foods predicted eCB levels in overweight women. Finally, we show that salivary eCBs correlate with body composition in women only. Our study shows that the food source has a differential impact on physiological and behavioural aspects of food intake.

Dissecting the Brain/Islet Axis in Metabesity

The high prevalence of type 2 diabetes mellitus (T2DM), together with the fact that current treatments are only palliative and do not avoid major secondary complications, reveals the need for novel approaches to treat the cause of this disease. Efforts are currently underway to identify therapeutic targets implicated in either the regeneration or re-differentiation of a functional pancreatic islet β-cell mass to restore insulin levels and normoglycemia. However, T2DM is not only caused by failures in β-cells but also by dysfunctions in the central nervous system (CNS), especially in the hypothalamus and brainstem. Herein, we review the physiological contribution of hypothalamic neuronal and glial populations, particularly astrocytes, in the control of the systemic response that regulates blood glucose levels. The glucosensing capacity of hypothalamic astrocytes, together with their regulation by metabolic hormones, highlights the relevance of these cells in the control of glucose homeostasis. Moreover, the critical role of astrocytes in the response to inflammation, a process associated with obesity and T2DM, further emphasizes the importance of these cells as novel targets to stimulate the CNS in response to metabesity (over-nutrition-derived metabolic dysfunctions). We suggest that novel T2DM therapies should aim at stimulating the CNS astrocytic response, as well as recovering the functional pancreatic β-cell mass. Whether or not a common factor expressed in both cell types can be feasibly targeted is also discussed.

Effect of acute Δ9-tetrahydrocannabinol administration on subjective and metabolic hormone responses to food stimuli and food intake in healthy humans: a randomized, placebo-controlled study

BACKGROUND

The endocannabinoid system (ECS) is considered a key player in the neurophysiology of food reward. Animal studies suggest that the ECS stimulates the sensory perception of food, thereby increasing its incentive-motivational and/or hedonic properties and driving consumption, possibly via interactions with metabolic hormones. However, it remains unclear to what extent this can be extrapolated to humans.

OBJECTIVE

We aimed to investigate the effect of oral Δ9-tetrahydrocannabinol (THC) on subjective and metabolic hormone responses to visual food stimuli and food intake.

METHODS

Seventeen healthy subjects participated in a single-blinded, placebo-controlled, 2 × 2 crossover trial. In each of the 4 visits, subjective "liking" and "wanting" ratings of high- and low-calorie food images were acquired after oral THC or placebo administration. The effect on food intake was quantified in 2 ways: via ad libitum oral intake (half of the visits) and intragastric infusion (other half) of chocolate milkshake. Appetite-related sensations and metabolic hormones were measured at set time points throughout each visit.

RESULTS

THC increased "liking" (P = 0.031) and "wanting" ratings (P = 0.0096) of the high-calorie, but not the low-calorie images, compared with placebo. Participants consumed significantly more milkshake after THC than after placebo during oral intake (P = 0.0005), but not intragastric infusion, of milkshake. Prospective food consumption ratings during the food image paradigm were higher after THC than after placebo (P = 0.0039). THC also increased plasma motilin (P = 0.0021) and decreased octanoylated ghrelin (P = 0.023) concentrations before milkshake consumption (i.e., in both oral intake and intragastric infusion test sessions), whereas glucagon-like peptide 1 responses to milkshake intake were attenuated by THC during both oral (P = 0.0002) and intragastric (P = 0.0055) administration.

CONCLUSIONS

These findings suggest that the ECS drives food intake by interfering with anticipatory, cephalic phase, and metabolic hormone responses. This trial was registered at clinicaltrials.gov as NCT02310347.

Role of Endocannabinoids on Sweet Taste Perception, Food Preference, and Obesity-related Disorders

The prevalence of obesity and obesity-related disorders such as type 2 diabetes (T2D) and metabolic syndrome has increased significantly in the past decades, reaching epidemic levels and therefore becoming a major health issue worldwide. Chronic overeating of highly palatable foods is one of the main responsible aspects behind overweight. Food choice is driven by food preference, which is influenced by environmental and internal factors, from availability to rewarding properties of food. Consequently, the acquisition of a dietary habit that may lead to metabolic alterations is the result of a learning process in which many variables take place. From genetics to socioeconomic status, the response to food and how this food affects energy metabolism is heavily influenced, even before birth. In this work, we review how food preference is acquired and established, particularly as regards sweet taste; towards which flavors and tastes we are positively predisposed by our genetic background, our early experience, further lifestyle, and our surroundings; and, especially, the role that the endocannabinoid system (ECS) plays in all of this. Ultimately, we try to summarize why this system is relevant for health purposes and how this is linked to important aspects of eating behavior, as its function as a modulator of energy homeostasis affects, and is affected by, physiological responses directly associated with obesity.

The effect of cannabinoid receptor 1 blockade on adipokine and proinflammatory cytokine concentration in adipose and hepatic tissue in mice with nonalcoholic fatty liver disease

In high-fat diet (HFD) induced nonalcoholic fatty liver disease (NAFLD), there is an increase in the endocannabinoid system activity, which significantly contributes to steatosis development. The aim of our study was to investigate the effects of cannabinoid receptor type 1 blockade on adipokine and proinflammatory cytokine content in adipose and hepatic tissue in mice with NAFLD. Male mice C57BL/6 were divided into a control group fed with a control diet for 20 weeks (C, n = 6) a group fed with a HFD for 20 weeks (HF, n = 6), a group fed with a control diet and treated with rimonabant after 18 weeks (R, n = 9), and a group fed with HFD and treated with rimonabant after 18 weeks (HFR, n = 10). Rimonabant significantly decreased leptin, resistin, apelin, visfatin, interleukin 6 (IL-6), and interferon-γ (IFN-γ) concentration in subcutaneous and visceral adipose tissue in the HFR group compared to the HF group (p < 0.01). Rimonabant reduced hepatic IL-6 and IFN-γ concentration as well as plasma glucose and insulin concentration and the homeostatic model assessment index in the HFR group compared to the HF group (p < 0.01). It can be concluded that the potential usefulness of CB1 blockade in the treatment of HFD-induced NAFLD is due to modulation of the adipokine profile and proinflammatory cytokines in both adipose tissues and liver as well as glucose metabolism.

Obesity-induced changes in lipid mediators persist after weight loss

BACKGROUND

Obesity induces significant changes in lipid mediators, however, the extent to which these changes persist after weight loss has not been investigated.

SUBJECTS/METHODS

We fed C57BL6 mice a high-fat diet to generate obesity and then switched the diet to a lower-fat diet to induce weight loss. We performed a comprehensive metabolic profiling of lipid mediators including oxylipins, endocannabinoids, sphingosines and ceramides in key metabolic tissues (including adipose, liver, muscle and hypothalamus) and plasma.

RESULTS

We found that changes induced by obesity were largely reversible in most metabolic tissues but the adipose tissue retained a persistent obese metabolic signature. Prostaglandin signaling was perturbed in the obese state and lasting increases in PGD2, and downstream metabolites 15-deoxy PGJ2 and delta-12-PGJ2 were observed after weight loss. Furthermore expression of the enzyme responsible for PGD2 synthesis (hematopoietic prostaglandin D synthase, HPGDS) was increased in obese adipose tissues and remained high after weight loss. We found that inhibition of HPGDS over the course of 5 days resulted in decreased food intake in mice. Increased HPGDS expression was also observed in human adipose tissues obtained from obese compared with lean individuals. We then measured circulating levels of PGD2 in obese patients before and after weight loss and found that while elevated relative to lean subjects, levels of this metabolite did not decrease after significant weight loss.

CONCLUSIONS

These results suggest that lasting changes in lipid mediators induced by obesity, still present after weight loss, may play a role in the biological drive to regain weight.

Protective effect of rimonabant, a canabinoid receptor 1 antagonist, on nonalcoholic fatty liver disease in a rat model through modulation of the hepatic expression of activin A and follistatin

Non-alcoholic fatty liver disease (NAFLD) is a major cause of liver morbidity and mortality, and there is still no proven effective therapy. The endocannabinoid system plays an important role in various liver diseases. Activin A is a member of the transforming growth factor beta (TGF-β) superfamily and inhibits hepatocyte growth. Follistatin antagonizes the biological actions of activin A. This study was designed to investigate the effect of rimonabant (a potent cannabinoid receptor1 (CB1) antagonist) on NAFLD induced with a choline-deficient (CD) diet in rats, as well as to detect whether it can alter the hepatic expression of activin A and follistatin. Forty rats were distributed among 4 groups: the control group, the rimonabant treatment group (normal rats that received rimonabant); the CD diet group (NAFLD induced with a CD diet); and the CD diet + rimonabant group (NAFLD treated with rimonabant). It was found that the CD diet caused significant increase in liver index, serum levels of liver enzymes, malondialdehyde (MDA), TGF-β1, activin A, and CB1 expression in liver tissue, with a significant decrease in glutathione peroxidase (GSH-Px) and follistatin mRNA expression in liver tissues. The administration of rimonabant significantly improved all of the studied parameters compared with the group fed the CD diet alone. Histopathological examination supported these results. We concluded that rimonabant significantly counteracted NAFLD induced with the CD diet by decreasing oxidative stress and hepatic expression of TGF-β1, and modulating the hepatic expression of activin A and follistatin.

The effect of cannabinoid receptor 1 blockade on hepatic free fatty acid profile in mice with nonalcoholic fatty liver disease

We used rimonabant to investigate the role of CB1 receptor on hepatic FFAs profile during NAFLD. Male mice C57BL/6 were divided into: control group fed with control diet 20 weeks (C; n=6); group fed with HFD 20 weeks (HF; n=6); group fed with control diet and treated with rimonabant after 18 weeks (R; n=9); group fed with HFD and treated with rimonabant after 18 weeks (HFR; n=10). Rimonabant (10mg/kg) was administered daily to HFR and R group by oral gavage. Rimonabant decreased liver palmitic acid proportion in HFR group compared to HF group (p<0.05). Liver stearic and oleic acid proportions were decreased in R group compared to control (p<0.01 respectively). Rimonabant increased liver linoleic and arachidonic acid proportions in HFR group compared to HF group (p<0.01 respectively). CB1 blockade may be useful in the treatment of HFD-induced NAFLD due to modulation of plasma lipid and hepatic FFA profile.

Obesity development in neuron-specific lipoprotein lipase deficient mice is not responsive to increased dietary fat content or change in fat composition

We have previously reported that mice with neuron-specific LPL deficiency (NEXLPL-/-) become obese by 16weeks of age on chow. Moreover, these mice had reduced uptake of triglyceride (TG)-rich lipoprotein-derived fatty acids and lower levels of n-3 long chain polyunsaturated fatty acids (n-3 PUFAs) in the hypothalamus. Here, we asked whether increased dietary fat content or altered dietary composition could modulate obesity development in NEXLPL-/- mice. Male NEXLPL-/- mice and littermate controls (WT) were randomly assigned one of three synthetic diets; a high carbohydrate diet (HC, 10% fat), a high-fat diet (HF, 45% fat), or a HC diet supplemented with n-3 PUFAs (HCn-3, 10% fat, Lovaza, GSK®). After 42weeks of HC feeding, body weight and fat mass were increased in the NEXLPL-/- mice compared to WT. WT mice fed a HF diet displayed typical diet-induced obesity, but weight gain was only marginal in HF-fed NEXLPL-/- mice, with no significant difference in body composition. Dietary n-3 PUFA supplementation did not prevent obesity in NEXLPL-/- mice, but was associated with differential modifications in hypothalamic gene expression and PUFA concentration compared to WT mice. Our findings suggest that neuronal LPL is involved in the regulation of body weight and composition in response to either the change in quantity (HF feeding) or quality (n-3 PUFA-enriched) of dietary fat. The precise role of LPL in lipid sensing in the brain requires further investigation.

Deletion of G-protein-coupled receptor 55 promotes obesity by reducing physical activity

BACKGROUND/OBJECTIVES

Cannabinoid receptor 1 (CB1) is the best-characterized cannabinoid receptor, and CB1 antagonists are used in clinical trials to treat obesity. Because of the wide range of CB1 functions, the side effects of CB1 antagonists pose serious concerns. G-protein-coupled receptor 55 (GPR55) is an atypical cannabinoid receptor, and its pharmacology and functions are distinct from CB1. GPR55 regulates neuropathic pain, gut, bone, immune functions and motor coordination. GPR55 is expressed in various brain regions and peripheral tissues. However, the roles of GPR55 in energy and glucose homeostasis are unknown. Here we have investigated the roles of GPR55 in energy balance and insulin sensitivity using GPR55-null mice (GPR55(-/-)).

METHODS

Body composition of the mice was measured by EchoMRI. Food intake, feeding behavior, energy expenditure and physical activity of GPR55(-/-) mice were determined by indirect calorimetry. Muscle function was assessed by forced treadmill running test. Insulin sensitivity was evaluated by glucose and insulin tolerance tests. Adipose inflammation was assessed by flow cytometry analysis of adipose tissue macrophages. The expression of inflammatory markers in adipose tissues and orexigenic/anorexigenic peptides in the hypothalamus was also analyzed by real-time PCR.

RESULTS

GPR55(-/-) mice had normal total energy intake and feeding pattern (i.e., no changes in meal size, meal number or feeding frequency). Intriguingly, whereas adult GPR55(-/-) mice only showed a modest increase in overall body weight, they exhibited significantly increased fat mass and insulin resistance. The spontaneous locomotor activity of GPR55(-/-) mice was dramatically decreased, whereas resting metabolic rate and non-shivering thermogenesis were unchanged. Moreover, GPR55(-/-) mice exhibited significantly decreased voluntary physical activity, showing reduced running distance on the running wheels, whereas muscle function appeared to be normal.

CONCLUSIONS

GPR55 has an important role in energy homeostasis. GPR55 ablation increases adiposity and insulin resistance by selectively decreasing physical activity, but not by altering feeding behavior as CB1.

Examination of the Addictive and Behavioral Properties of Fatty Acid-Binding Protein Inhibitor SBFI26

The therapeutic properties of cannabinoids have been well demonstrated but are overshadowed by such adverse effects as cognitive and motor dysfunction, as well as their potential for addiction. Recent research on the natural lipid ligands of cannabinoid receptors, also known as endocannabinoids, has shed light on the mechanisms of intracellular transport of the endocannabinoid anandamide by fatty acid-binding proteins (FABPs) and subsequent catabolism by fatty acid amide hydrolase. These findings facilitated the recent development of SBFI26, a pharmacological inhibitor of epidermal- and brain-specific FABP5 and FABP7, which effectively increases anandamide signaling. The goal of this study was to examine this compound for any possible rewarding and addictive properties as well as effects on locomotor activity, working/recognition memory, and propensity for sociability and preference for social novelty (SN) given its recently reported anti-inflammatory and analgesic properties. Male C57BL mice were split into four treatment groups and conditioned with 5.0, 20.0, 40.0 mg/kg SBFI26, or vehicle during a conditioned place preference (CPP) paradigm. Following CPP, mice underwent a battery of behavioral tests [open field, novel object recognition (NOR), social interaction (SI), and SN] paired with acute SBFI26 administration. Results showed that SBFI26 did not produce CPP or conditioned place aversion regardless of dose and did not induce any differences in locomotor and exploratory activity during CPP- or SBFI26-paired open field activity. We also observed no differences between treatment groups in NOR, SI, and SN. In conclusion, as SBFI26 was shown previously by our group to have significant analgesic and anti-inflammatory properties, here we show that it does not pose a risk of dependence or motor and cognitive impairment under the conditions tested.

Ultrastructural evidence for synaptic contacts between cortical noradrenergic afferents and endocannabinoid-synthesizing post-synaptic neurons

Endocannabinoids (eCBs) are involved in a myriad of physiological processes that are mediated through the activation of cannabinoid receptors, which are ubiquitously distributed within the nervous system. One neurochemical target at which cannabinoids interact to have global effects on behavior is brain noradrenergic circuitry. We, and others, have previously shown that CB type 1 receptors (CB1r) are positioned to pre-synaptically modulate norepinephrine (NE) release in the rat frontal cortex (FC). Diacylglycerol lipase (DGL) is a key enzyme in the biosynthesis of the endocannabinoid 2-arachidonoylglycerol (2-AG). While DGL-α is expressed in the FC in the rat brain, it is not known whether noradrenergic afferents target neurons expressing synthesizing enzymes for the endocannabinoid, 2-AG. In the present study, we employed high-resolution neuroanatomical approaches to better define cellular sites for interactions between noradrenergic afferents and FC neurons expressing DGL-α. Immunofluorescence microscopy showed close appositions between processes containing the norepinephrine transporter (NET) or dopamine-β-hydroxylase (DβH) and cortical neurons expressing DGL-α-immunoreactivity. Ultrastructural analysis using immunogold-silver labeling for DGL-α and immunoperoxidase labeling for NET or DβH confirmed that NET-labeled axon terminals were directly apposed to FC somata and dendritic processes that exhibited DGL-α-immunoreactivity. Finally, tissue sections were processed for immunohistochemical detection of DGL-α, CB1r and DβH. Triple label immunofluorescence revealed that CB1r and DβH were co-localized in common cellular profiles and these were in close association with DGL-α. Taken together, these data provide anatomical evidence for direct synaptic associations between noradrenergic afferents and cortical neurons exhibiting endocannabinoid synthesizing machinery.

Rimonabant Improves Oxidative/Nitrosative Stress in Mice with Nonalcoholic Fatty Liver Disease

The present study deals with the effects of rimonabant on oxidative/nitrosative stress in high diet- (HFD-) induced experimental nonalcoholic fatty liver disease (NAFLD). Male mice C57BL/6 were divided into the following groups: control group fed with control diet for 20 weeks (C; n = 6); group fed with HFD for 20 weeks (HF; n = 6); group fed with standard diet and treated with rimonabant after 18 weeks (R; n = 9); group fed with HFD and treated with rimonabant after 18 weeks (HFR; n = 10). Daily dose of rimonabant (10 mg/kg) was administered to HFR and R group by oral gavage for two weeks. Treatment induced a decrease in hepatic malondialdehyde concentration in HFR group compared to HF group (P < 0.01). The concentration of nitrites + nitrates in liver was decreased in HFR group compared to HF group (P < 0.01). Liver content of reduced glutathione was higher in HFR group compared to HF group (P < 0.01). Total liver superoxide dismutase activity in HFR group was decreased in comparison with HF group (P < 0.01). It was found that rimonabant may influence hepatic iron, zinc, copper, and manganese status. Our study indicates potential usefulness of cannabinoid receptor type 1 blockade in the treatment of HFD-induced NAFLD.