Cannabinoids inhibit insulin receptor signaling in pancreatic β-cells

Δ9-Tetrahydrocannabinol Treatment Modifies Insulin Secretion in Pancreatic Islets from Prediabetic Mice Under Hypercaloric Diet

Background: The endocannabinoid system over-activation is associated with type-2 diabetes mellitus onset, involving physiological, metabolic, and genetic alterations in pancreatic islets. The use of Δ9-Tetrahydrocannabinol (THC) as treatment is still controversial since its effects and mechanisms on insulin secretion are unclear. The aim of this study was to evaluate the effects of THC treatment in pancreatic islets from prediabetic mice. Methods: Prediabetes was induced in mice by hypercaloric diet, and then treated with THC for 3 weeks. Blood glucose and body weight were determined, after behavior tests. Histological changes were evaluated in whole pancreas; in isolated islets we analyzed the effect of THC exposure in glucose-stimulated insulin secretion (GSIS), gene expression, intracellular cyclic adenosine monophosphate (cAMP), and cytosolic calcium changes. Results: THC treatment in prediabetic mice enhanced anxiety and antidepressive behavior without changes in food ingestion, decreased oral-glucose tolerance test, plasma insulin and weight, with small alterations on pancreatic histology. In isolated islets from healthy mice THC increased GSIS, cAMP, and CB1 receptor (CB1r) expression, meanwhile calcium release was diminished. Small changes were observed in islets from prediabetic mice. Conclusions: THC treatment improves some clinical parameters in prediabetic mice, however, in isolated islets, modifies GSIS, intracellular calcium and gene expression, suggesting specific effects related to diabetes evolution.

Pharmaceutical targeting of the cannabinoid type 1 receptor impacts the crosstalk between immune cells and islets to reduce insulitis in humans

AIMS/HYPOTHESIS

Insulitis, a hallmark of inflammation preceding autoimmune type 1 diabetes, leads to the eventual loss of functional beta cells. However, functional beta cells can persist even in the face of continuous insulitis. Despite advances in immunosuppressive treatments, maintaining functional beta cells to prevent insulitis progression and hyperglycaemia remains a challenge. The cannabinoid type 1 receptor (CB1R), present in immune cells and beta cells, regulates inflammation and beta cell function. Here, we pioneer an ex vivo model mirroring human insulitis to investigate the role of CB1R in this process.

METHODS

CD4+ T lymphocytes were isolated from peripheral blood mononuclear cells (PBMCs) from male and female individuals at the onset of type 1 diabetes and from non-diabetic individuals, RNA was extracted and mRNA expression was analysed by real-time PCR. Single beta cell expression from donors with type 1 diabetes was obtained from data mining. Patient-derived human islets from male and female cadaveric donors were 3D-cultured in solubilised extracellular matrix gel in co-culture with the same donor PBMCs, and incubated with cytokines (IL-1β, TNF-α, IFN-γ) for 24-48 h in the presence of vehicle or increasing concentrations of the CB1R blocker JD-5037. Expression of CNR1 (encoding for CB1R) was ablated using CRISPR/Cas9 technology. Viability, intracellular stress and signalling were assayed by live-cell probing and real-time PCR. The islet function measured as glucose-stimulated insulin secretion was determined in a perifusion system. Infiltration of immune cells into the islets was monitored by microscopy. Non-obese diabetic mice aged 7 weeks were treated for 1 week with JD-5037, then euthanised. Profiling of immune cells infiltrated in the islets was performed by flow cytometry.

RESULTS

CNR1 expression was upregulated in circulating CD4+ T cells from individuals at type 1 diabetes onset (6.9-fold higher vs healthy individuals) and in sorted islet beta cells from donors with type 1 diabetes (3.6-fold higher vs healthy counterparts). The peripherally restricted CB1R inverse agonist JD-5037 arrested the initiation of insulitis in humans and mice. Mechanistically, CB1R blockade prevented islet NO production and ameliorated the ATF6 arm of the unfolded protein response. Consequently, cyto/chemokine expression decreased in human islets, leading to sustained islet cell viability and function.

CONCLUSIONS/INTERPRETATION

These results suggest that CB1R could be an interesting target for type 1 diabetes while highlighting the regulatory mechanisms of insulitis. Moreover, these findings may apply to type 2 diabetes where islet inflammation is also a pathophysiological factor.

DATA AVAILABILITY

Transcriptomic analysis of sorted human beta cells are from Gene Expression Omnibus database, accession no. GSE121863, available at https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSM3448161 .

Cannabinoids Block Fat-induced Incretin Release via CB1-dependent and CB1-independent Pathways in Intestinal Epithelium

Background and Aims

Glucose homeostasis is regulated by a dynamic interplay between hormones along the gastro-insular axis. For example, enteroendocrine L- and K- cells that line the intestine produce the incretins glucagon-like peptide-1 (GLP1) and glucose-dependent insulinotropic polypeptide (GIP), respectively, which are secreted following a meal. Broadly, incretin signaling enhances insulin release from the endocrine pancreas and participates in the control of food intake, and therapeutics that mimic their activity have recently been developed for the treatment of type-2 diabetes and obesity. Notably, genes for cannabinoid subtype-1 receptor (CB1R) are expressed in these cell subpopulations; however, roles for CB1Rs in controlling fat-induced incretin release are unclear. To address this gap in our understanding, we tested the hypothesis that intestinal epithelial CB1Rs control fat-induced incretin secretion.

Methods

We treated mice with conditional deletion of CB1Rs in the intestinal epithelium (IntCB1-/-) or controls (IntCB1+/+) with oil gavage to stimulate incretin release in the presence of the cannabinoid receptor agonists, WIN55,212-2 or Δ9 tetrahydrocannabinol (THC), and the peripherally-restricted CB1R antagonist AM6545. Circulating incretin levels were measured in plasma.

Results

Oral gavage of corn oil increased levels of bioactive GLP1 and GIP in IntCB1+/+ mouse plasma. Pretreatment with the WIN55,212-2 or THC blocked this response, which was largely reversed by coadministration with AM6545. WIN55,212-2 failed to inhibit fat-induced GIP release, but not GLP1, in IntCB1-/- mice. In contrast, THC inhibited the secretion of incretins irrespective of CB1R expression in intestinal epithelial cells.

Conclusion

These results indicate that cannabinoid receptor agonists can differentially inhibit incretin release via mechanisms that include intestinal epithelial CB1R-dependent and CB1R-independent mechanisms.

Effects of prenatal THC vapor exposure on body weight, glucose metabolism, and feeding behaviors in chow and high-fat diet fed rats

BACKGROUND

4-20% of people report using cannabis during pregnancy, thereby it is essential to assess the associated risks. There is some evidence that prenatal cannabis exposure (PCE) may be associated with increased risk for developing of obesity and diabetes later in life, however this has not been well explored under controlled conditions. The aim of this study was to use a translational THC vapor model in rodents to characterize the effects of PCE on adiposity, glucose metabolism, and feeding patterns in adulthood, with focus on potential sex differences.

METHODS

Pregnant Sprague Dawley rats were exposed to vaporized THC (100 mg/ml) or control (polyethylene glycol vehicle) across the entire gestational period. Adult offspring from PCE (n = 24) or control (n = 24) litters were subjected to measures of adiposity, glucose metabolism and feeding behavior. Rats were then placed onto special diets (60% high-fat diet [HFD] or control 10% low fat diet [LFD]) for 4-months, then re-subjected to adiposity, glucose metabolism and feeding behavior measurements.

RESULTS

PCE did not influence maternal weight or food consumption but was associated with transient decreased pup weight. PCE did not initially influence bodyweight or adiposity, but PCE did significantly reduce the rate of bodyweight gain when on HFD/LFD, regardless of which diet. Further, PCE had complex effects on glucose metabolism and feeding behavior that were both sex and diet dependent. No effects of PCE were found on plasma leptin or insulin, or white adipose tissue mass.

CONCLUSIONS

PCE may not promote obesity development but may increase risk for diabetes and abnormal eating habits under certain biological and environmental conditions. Overall, this data enhances current understanding of the potential impacts of PCE.

Beta cell specific cannabinoid 1 receptor deletion counteracts progression to hyperglycemia in non-obese diabetic mice

OBJECTIVE

Type 1 diabetes (T1D) occurs because of islet infiltration by autoreactive immune cells leading to destruction of beta cells and it is becoming evident that beta cell dysfunction partakes in this process. We previously reported that genetic deletion and pharmacological antagonism of the cannabinoid 1 receptor (CB1) in mice improves insulin synthesis and secretion, upregulates glucose sensing machinery, favors beta cell survival by reducing apoptosis, and enhances beta cell proliferation. Moreover, beta cell specific deletion of CB1 protected mice fed a high fat high sugar diet against islet inflammation and beta cell dysfunction. Therefore, we hypothesized that it would mitigate the dysfunction of beta cells in the precipitating events leading to T1D.

METHODS

We genetically deleted CB1 specifically from beta cells in non-obese diabetic (NOD; NOD RIP Cre+ Cnr1fl/fl) mice. We evaluated female NOD RIP Cre+ Cnr1fl/fl mice and their NOD RIP Cre-Cnr1fl/fl and NOD RIP Cre+ Cnr1Wt/Wt littermates for onset of hyperglycemia over 26 weeks. We also examined islet morphology, islet infiltration by immune cells and beta cell function and proliferation.

RESULTS

Beta cell specific deletion of CB1 in NOD mice significantly reduced the incidence of hyperglycemia by preserving beta cell function and mass. Deletion also prevented beta cell apoptosis and aggressive insulitis in NOD RIP Cre+ Cnr1fl/fl mice compared to wild-type littermates. NOD RIP Cre+ Cnr1fl/fl islets maintained normal morphology with no evidence of beta cell dedifferentiation or appearance of extra islet beta cells, indicating that protection from autoimmunity is inherent to genetic deletion of beta cell CB1. Pancreatic lymph node Treg cells were significantly higher in NOD RIP Cre+ Cnr1fl/flvs NOD RIP Cre-Cnr1fl/fl.

CONCLUSIONS

Collectively these data demonstrate how protection of beta cells from metabolic stress during the active phase of T1D can ameliorate destructive insulitis and provides evidence for CB1 as a potential pharmacologic target in T1D.

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.

The function of the endocannabinoid system in the pancreatic islet and its implications on metabolic syndrome and diabetes

The following review focuses on the scientific studies related to the role of endocannabinoid system (ECS) in pancreatic islet physiology and dysfunction. Different natural or synthetic agonists and antagonists have been suggested as an alternative treatment for diabetes, obesity and metabolic syndrome. Therapeutic use of Cannabis led to the discovery and characterization of the ECS, a signaling complex involved in regulation of various physiological processes, including food intake and metabolism. After the development of different agonists and antagonists, evidence have demonstrated the presence and activity of cannabinoid receptors in several organs and tissues, including pancreatic islets. Insulin and glucagon expression, stimulated secretion, and the development of diabetes and other metabolic disorders have been associated with the activity and modulation of ECS in pancreatic islets. However, according to the animal model and experimental design, either endogenous or pharmacological ligands of cannabinoid receptors have guided to contradictory and paradoxical results that suggest a complex physiological interaction. In consensus, ECS activity modulates insulin and glucagon secretions according to glucose in media; over-stimulation of cannabinoid receptors affects islets negatively, leading to glucose intolerance, meanwhile the treatment with antagonists in diabetic models and humans suggests an improvement in islets function.

Exploring the Therapeutic Potential of Cannabinoid Receptor Antagonists in Inflammation, Diabetes Mellitus, and Obesity

Recently, research has greatly expanded the knowledge of the endocannabinoid system (ECS) and its involvement in several therapeutic applications. Cannabinoid receptors (CBRs) are present in nearly every mammalian tissue, performing a vital role in different physiological processes (neuronal development, immune modulation, energy homeostasis). The ECS has an essential role in metabolic control and lipid signaling, making it a potential target for managing conditions such as obesity and diabetes. Its malfunction is closely linked to these pathological conditions. Additionally, the immunomodulatory function of the ECS presents a promising avenue for developing new treatments for various types of acute and chronic inflammatory conditions. Preclinical investigations using peripherally restricted CBR antagonists that do not cross the BBB have shown promise for the treatment of obesity and metabolic diseases, highlighting the importance of continuing efforts to discover novel molecules with superior safety profiles. The purpose of this review is to examine the roles of CB1R and CB2Rs, as well as their antagonists, in relation to the above-mentioned disorders.

The endocannabinoid system, a new gatekeeper in the pharmacology of human hepatocellular carcinoma

Despite numerous prevention methodologies and treatment options, hepatocellular carcinoma (HCC) still remains as the third leading life-threatening cancer. It is thus pertinent to develop new treatment modality to fight this devastating carcinoma. Ample recent studies have shown the anti-inflammatory and antitumor roles of the endocannabinoid system in various forms of cancers. Preclinical studies have also confirmed that cannabinoid therapy can be an optimal regimen for cancer treatments. The endocannabinoid system is involved in many cancer-related processes, including induction of endoplasmic reticulum (ER) stress-dependent apoptosis, autophagy, PITRK and ERK signaling pathways, cell invasion, epithelial-mesenchymal transition (EMT), and cancer stem cell (CSC) phenotypes. Moreover, changes in signaling transduction of the endocannabinoid system can be a potential diagnostic and prognostic biomarker for HCC. Due to its pivotal role in lipid metabolism, the endocannabinoid system affects metabolic reprogramming as well as lipid content of exosomes. In addition, due to the importance of non-coding RNAs (ncRNAs), several studies have examined the relationship between microRNAs and the endocannabinoid system in HCC. However, HCC is a pathological condition with high heterogeneity, and therefore using the endocannabinoid system for treatment has faced many controversies. While some studies favored a role of the endocannabinoid system in carcinogenesis and tumor induction, others exhibited the anticancer potential of endocannabinoids in HCC. In this review, specific studies delineating the relationship between endocannabinoids and HCC are examined. Based on collected findings, detailed studies of the molecular mechanism of endocannabinoids as well as preclinical studies for investigating therapeutic or carcinogenic impacts in HCC cancer are strongly suggested.

A peripherally restricted cannabinoid-1 receptor inverse agonist promotes insulin secretion and protects from cytokine toxicity in human pancreatic islets

The cannabinoid receptor CB1R is expressed in pancreatic β-cells; CB1R increased activity is associated with diabetes, obesity, cardiovascular disorders as well as decreased insulin secretion and insulin resistance. CB1R was shown to signal through G-protein coupling as well as β-arrestins in β-cells. Peripherally restricted CB1R inverse agonists purportedly have beneficial effects on insulin secretion in β-cells, without the unwanted effects in the central nervous system. Here we show that a peripherally restricted CB1R inverse agonist, MRI-1891, augments glucose stimulated insulin secretion in isolated human pancreatic islets and mouse islets. The insulin secretion enhancing effect of MRI-1891 is comparable to exendin-4, an analogue of the glucagon like peptide-1 (GLP1). Moreover, MRI-1891 treatment protects isolated human islet cells against cytokine-induced apoptosis, similar to exendin-4. Thus, MRI-1891, a new class of CB1R inverse agonist, may be considered a potential therapeutic for both type 1 and type 2 diabetes because of its ability to protect pancreatic β-cells from cytokine toxicity and to promote insulin secretion.

Cannabinoids Transmogrify Cancer Metabolic Phenotype via Epigenetic Reprogramming and a Novel CBD Biased G Protein-Coupled Receptor Signaling Platform

The concept of epigenetic reprogramming predicts long-term functional health effects. This reprogramming can be activated by exogenous or endogenous insults, leading to altered healthy and different disease states. The exogenous or endogenous changes that involve developing a roadmap of epigenetic networking, such as drug components on epigenetic imprinting and restoring epigenome patterns laid down during embryonic development, are paramount to establishing youthful cell type and health. This epigenetic landscape is considered one of the hallmarks of cancer. The initiation and progression of cancer are considered to involve epigenetic abnormalities and genetic alterations. Cancer epigenetics have shown extensive reprogramming of every component of the epigenetic machinery in cancer development, including DNA methylation, histone modifications, nucleosome positioning, non-coding RNAs, and microRNA expression. Endocannabinoids are natural lipid molecules whose levels are regulated by specific biosynthetic and degradative enzymes. They bind to and activate two primary cannabinoid receptors, type 1 (CB1) and type 2 (CB2), and together with their metabolizing enzymes, form the endocannabinoid system. This review focuses on the role of cannabinoid receptors CB1 and CB2 signaling in activating numerous receptor tyrosine kinases and Toll-like receptors in the induction of epigenetic landscape alterations in cancer cells, which might transmogrify cancer metabolism and epigenetic reprogramming to a metastatic phenotype. Strategies applied from conception could represent an innovative epigenetic target for preventing and treating human cancer. Here, we describe novel cannabinoid-biased G protein-coupled receptor signaling platforms (GPCR), highlighting putative future perspectives in this field.

Role of the Endocannabinoid System in Metabolic Control Processes and in the Pathogenesis of Metabolic Syndrome: An Update

Metabolic syndrome is a complex disease state, which appears mostly as a consequence of an unhealthy, sedentary lifestyle. Metabolic complications include insulin resistance (IR), diabetes, dyslipidemia, hypertension, and atherosclerosis, impairing life standards and reducing life expectancy. The endocannabinoid system (ECS) has an important role in signalization processes, not only in the central nervous system, but also in the peripheral tissues. Several physiological functions are affected, and overexpression or downregulation contributes to several diseases. A better understanding of the functions of cannabinoid (CB) receptors may propose potential therapeutic effects by influencing receptor signaling and enzymes involved in downstream pathways. In this review, we summarize recent information regarding the roles of the ECS and the CB₁ receptor signaling in the physiology and pathophysiology of energy and metabolic homeostasis, in the development of obesity by enhancing food intake, upregulating energy balance and fat accumulation, increasing lipogenesis and glucose production, and impairing insulin sensitivity and secretion. By analyzing the roles of the ECS in physiological and pathophysiological mechanisms, we introduce some recently identified signaling pathways in the mechanism of the pathogenesis of metabolic syndrome. Our review emphasizes that the presence of such recently identified ECS signaling steps raises new therapeutic potential in the treatment of complex metabolic diseases such as diabetes, insulin resistance, obesity, and hypertension.

Sex-dependent Effect of In-utero Exposure to Δ9-Tetrahydrocannabinol on Glucagon and Stathmin-2 in Adult Rat Offspring

OBJECTIVES

Administration of Δ⁹-tetrahydrocannabinol (Δ⁹-THC) to pregnant rats results in glucose intolerance, insulin resistance and reduced islet mass in female, but not male, offspring. The effects of Δ⁹-THC on other islet hormones is not known. One downstream target of the cannabinoid receptor, stathmin-2 (Stmn2), has recently been shown to suppress glucagon secretion, thereby suggesting Δ⁹-THC may also affect alpha-cell function. The aim of the present study was to determine the effects of in-utero Δ⁹-THC exposure on the profile of glucagon, insulin and Stmn2 in the rat offspring islet and serum.

METHODS

Pregnant Wistar rat dams were injected with Δ⁹-THC (3 mg/kg per day, intraperitoneally) or vehicle from gestational day 6 to birth. Offspring were euthanized at postnatal day 21 (PND21) or at 5 months (adult) to collect blood and pancreata.

RESULTS

At PND21, control and Δ⁹-THC-exposed offspring showed that Stmn2 had a strong colocalization with glucagon (Pearson's correlation coefficient ≥0.6), and a weak colocalization with insulin (Pearson's correlation coefficient <0.4) in both males and females, with no changes by either treatment or sex. In adult female offspring in the Δ⁹-THC group, intensity analysis indicated an increased insulin-to-glucagon (I/G; p<0.05) ratio and a decreased glucagon-to-Stmn2 (G/S; p<0.01) ratio, and no changes in these ratios in adult males. Furthermore, Δ⁹-THC did not alter fasting blood glucose and serum insulin levels in either male or female adult offspring. However, female Δ⁹-THC-exposed offspring exhibited an increased I/G ratio (p<0.05) and decreased G/S ratio in serum by adulthood (p<0.05).

CONCLUSION

Collectively, the reduced G/S ratio in both islet and serum in association with an increased serum I/G ratio has direct correlations with early glucose intolerance and insulin resistance observed exclusively in females' offspring in this prenatal cannabinoid model.

The Relaxin-3 Receptor, RXFP3, Is a Modulator of Aging-Related Disease

During the aging process our body becomes less well equipped to deal with cellular stress, resulting in an increase in unrepaired damage. This causes varying degrees of impaired functionality and an increased risk of mortality. One of the most effective anti-aging strategies involves interventions that combine simultaneous glucometabolic support with augmented DNA damage protection/repair. Thus, it seems prudent to develop therapeutic strategies that target this combinatorial approach. Studies have shown that the ADP-ribosylation factor (ARF) GTPase activating protein GIT2 (GIT2) acts as a keystone protein in the aging process. GIT2 can control both DNA repair and glucose metabolism. Through in vivo co-regulation analyses it was found that GIT2 forms a close coexpression-based relationship with the relaxin-3 receptor (RXFP3). Cellular RXFP3 expression is directly affected by DNA damage and oxidative stress. Overexpression or stimulation of this receptor, by its endogenous ligand relaxin 3 (RLN3), can regulate the DNA damage response and repair processes. Interestingly, RLN3 is an insulin-like peptide and has been shown to control multiple disease processes linked to aging mechanisms, e.g., anxiety, depression, memory dysfunction, appetite, and anti-apoptotic mechanisms. Here we discuss the molecular mechanisms underlying the various roles of RXFP3/RLN3 signaling in aging and age-related disorders.

Nampt activator P7C3 ameliorates diabetes and improves skeletal muscle function modulating cell metabolism and lipid mediators

BACKGROUND

Nicotinamide phosphoribosyltransferase (Nampt), a key enzyme in NAD salvage pathway is decreased in metabolic diseases, and its precise role in skeletal muscle function is not known. We tested the hypothesis, Nampt activation by P7C3 (3,6-dibromo-α-[(phenylamino)methyl]-9H-carbazol-9-ethanol) ameliorates diabetes and muscle function.

METHODS

We assessed the functional, morphometric, biochemical, and molecular effects of P7C3 treatment in skeletal muscle of type 2 diabetic (db/db) mice. Nampt^+/- mice were utilized to test the specificity of P7C3.

RESULTS

Insulin resistance increased 1.6-fold in diabetic mice compared with wild-type mice and after 4 weeks treatment with P7C3 rescued diabetes (P < 0.05). In the db-P7C3 mice fasting blood glucose levels decreased to 0.96-fold compared with C57Bl/6J wild-type naïve control mice. The insulin and glucose tolerance tests blood glucose levels were decreased to 0.6-fold and 0.54-folds, respectively, at 120 min along with an increase in insulin secretion (1.76-fold) and pancreatic β-cells (3.92-fold) in db-P7C3 mice. The fore-limb and hind-limb grip strengths were increased to 1.13-fold and 1.17-fold, respectively, together with a 14.2-fold increase in voluntary running wheel distance in db-P7C3 mice. P7C3 treatment resulted in a 1.4-fold and 7.1-fold increase in medium-sized and larger-sized myofibres cross-sectional area, with a concomitant 0.5-fold decrease in smaller-sized myofibres of tibialis anterior (TA) muscle. The transmission electron microscopy images also displayed a 1.67-fold increase in myofibre diameter of extensor digitorum longus muscle along with 2.9-fold decrease in mitochondrial area in db-P7C3 mice compared with db-Veh mice. The number of SDH positive myofibres were increased to 1.74-fold in db-P7C3 TA muscles. The gastrocnemius and TA muscles displayed a decrease in slow oxidative myosin heavy chain type1 (MyHC1) myofibres expression (0.46-fold) and immunostaining (6.4-fold), respectively. qPCR analysis displayed a 2.9-fold and 1.3-fold increase in Pdk4 and Cpt1, and 0.55-fold and 0.59-fold decrease in Fgf21 and 16S in db-P7C3 mice. There was also a 3.3-fold and 1.9-fold increase in Fabp1 and CD36 in db-Veh mice. RNA-seq differential gene expression volcano plot displayed 1415 genes to be up-regulated and 1726 genes down-regulated (P < 0.05) in db-P7C3 mice. There was 1.02-fold increase in serum HDL, and 0.9-fold decrease in low-density lipoprotein/very low-density lipoprotein ratio in db-P7C3 mice. Lipid profiling of gastrocnemius muscle displayed a decrease in inflammatory lipid mediators n-6; AA (0.83-fold), and n-3; DHA (0.69-fold) and EPA (0.81-fold), and a 0.66-fold decrease in endocannabinoid 2-AG and 2.0-fold increase in AEA in db-P7C3 mice.

CONCLUSIONS

Overall, we demonstrate that P7C3 activates Nampt, improves type 2 diabetes and skeletal muscle function in db/db mice.

Chronic marijuana usage by human pancreas donors is associated with impaired islet function

We investigated the effect of chronic marijuana use, defined as 4 times weekly for more than 3 years, on human pancreatic islets. Pancreata from deceased donors who chronically used marijuana were compared to those from age, sex and ethnicity matched non-users. The islets from marijuana-users displayed reduced insulin secretion as compared to islets from non-users upon stimulation with high glucose (AUC, 3.41 ± 0.62 versus 5.14 ±0.47, p<0.05) and high glucose plus KCl (AUC, 4.48 ± 0.41 versus 7.69 ± 0.58, p<0.001). When human islets from chronic marijuana-users were transplanted into diabetic mice, the mean reversal rate of diabetes was 35% versus 77% in animals receiving islets from non-users (p<0.01). Immunofluorescent staining for cannabinoid receptor type 1 (CB1R) was shown to be colocalized with insulin and enhanced significantly in beta cells from marijuana-users vs. non-users (CB1R intensity/islet area, 14.95 ± 2.71 vs. 3.23 ± 0.87, p<0.001). In contrast, CB1R expression was not co-localized with glucagon or somatostatin. Furthermore, isolated islets from chronic marijuana-users appeared hypertrophic. In conclusion, excessive marijuana use affects islet endocrine phenotype and function in vitro and in vivo. Given the increasing use of marijuana, our results underline the importance of including lifestyle when evaluating human islets for transplantation or research.

The Peripheral Cannabinoid Receptor Type 1 (CB1) as a Molecular Target for Modulating Body Weight in Man

The cannabinoid 1 (CB₁) receptor regulates appetite and body weight; however, unwanted central side effects of both agonists (in wasting disorders) or antagonists (in obesity and diabetes) have limited their therapeutic utility. At the peripheral level, CB₁ receptor activation impacts the energy balance of mammals in a number of different ways: inhibiting satiety and emesis, increasing food intake, altering adipokine and satiety hormone levels, altering taste sensation, decreasing lipolysis (fat break down), and increasing lipogenesis (fat generation). The CB₁ receptor also plays an important role in the gut–brain axis control of appetite and satiety. The combined effect of peripheral CB₁ activation is to promote appetite, energy storage, and energy preservation (and the opposite is true for CB₁ antagonists). Therefore, the next generation of CB₁ receptor medicines (agonists and antagonists, and indirect modulators of the endocannabinoid system) have been peripherally restricted to mitigate these issues, and some of these are already in clinical stage development. These compounds also have demonstrated potential in other conditions such as alcoholic steatohepatitis and diabetic nephropathy (peripherally restricted CB₁ antagonists) and pain conditions (peripherally restricted CB₁ agonists and FAAH inhibitors). This review will discuss the mechanisms by which peripheral CB₁ receptors regulate body weight, and the therapeutic utility of peripherally restricted drugs in the management of body weight and beyond.

The Impact of Early Life Exposure to Cannabis: The Role of the Endocannabinoid System

Cannabis use during pregnancy has continued to rise, particularly in developed countries, as a result of the trend towards legalization and lack of consistent, evidence-based knowledge on the matter. While there is conflicting data regarding whether cannabis use during pregnancy leads to adverse outcomes such as stillbirth, preterm birth, low birthweight, or increased admission to neonatal intensive care units, investigations into long-term effects on the offspring’s health are limited. Historically, studies have focused on the neurobehavioral effects of prenatal cannabis exposure on the offspring. The effects of cannabis on other physiological aspects of the developing fetus have received less attention. Importantly, our knowledge about cannabinoid signaling in the placenta is also limited. The endocannabinoid system (ECS) is present at early stages of development and represents a potential target for exogenous cannabinoids in utero. The ECS is expressed in a broad range of tissues and influences a spectrum of cellular functions. The aim of this review is to explore the current evidence surrounding the effects of prenatal exposure to cannabinoids and the role of the ECS in the placenta and the developing fetus.

Peripheral CB1R as a modulator of metabolic inflammation

Obesity is associated with chronic inflammation in insulin-sensitive tissues, including liver and adipose tissue, and causes hormonal/metabolic complications, such as insulin resistance. There is growing evidence that peripheral cannabinoid-type 1 receptor (CB1R) is a crucial participant in obesity-induced pro-inflammatory responses in insulin-target tissues, and its selective targeting could be a novel therapeutic strategy to break the link between insulin resistance and metabolic inflammation. In this review, we introduce the role of peripheral CB1R in metabolic inflammation and as a mediator of hormonal/metabolic complications that underlie metabolic syndrome, including fatty liver, insulin resistance, and dyslipidemia. We also discuss the therapeutic potential of second- and third-generation peripherally restricted CB1R antagonists for treating obesity-induced metabolic inflammation without eliciting central CB1R-mediated neurobehavioral effects, predictive of neuropsychiatric side effects, in humans.

The Interplay between the Immune and the Endocannabinoid Systems in Cancer

The therapeutic potential of Cannabis sativa has been recognized since ancient times. Phytocannabinoids, endocannabinoids and synthetic cannabinoids activate two major G protein-coupled receptors, subtype 1 and 2 (CB1 and CB2). Cannabinoids (CBs) modulate several aspects of cancer cells, such as apoptosis, autophagy, proliferation, migration, epithelial-to-mesenchymal transition and stemness. Moreover, agonists of CB1 and CB2 receptors inhibit angiogenesis and lymphangiogenesis in vitro and in vivo. Low-grade inflammation is a hallmark of cancer in the tumor microenvironment (TME), which contains a plethora of innate and adaptive immune cells. These cells play a central role in tumor initiation and growth and the formation of metastasis. CB2 and, to a lesser extent, CB1 receptors are expressed on a variety of immune cells present in TME (e.g., T cells, macrophages, mast cells, neutrophils, NK cells, dendritic cells, monocytes, eosinophils). The activation of CB receptors modulates a variety of biological effects on cells of the adaptive and innate immune system. The expression of CB2 and CB1 on different subsets of immune cells in TME and hence in tumor development is incompletely characterized. The recent characterization of the human cannabinoid receptor CB2-G_i signaling complex will likely aid to design potent and specific CB2/CB1 ligands with therapeutic potential in cancer.

Direct Stimulatory Effects of the CB2 Ligand JTE 907 in Human and Mouse Islets

AIMS

The endocannabinoid system is a complex cell-signaling network through which endogenous cannabinoid ligands regulate cell function by interaction with CB1 and CB2 cannabinoid receptors, and with the novel cannabinoid receptor GPR55. CB1, CB2, and GPR55 are expressed by islet β-cells where they modulate insulin secretion. We have previously shown that administration of the putative CB2 antagonist/inverse agonist JTE 907 to human islets did not affect the insulinotropic actions of CB2 agonists and it unexpectedly stimulated insulin secretion on its own. In this study, we evaluated whether the lack of antagonism could be related to the ability of JTE 907 to act as a GPR55 agonist.

MATERIALS AND METHODS

We used islets isolated from human donors and from Gpr55+/+ and Gpr55-/- mice and quantified the effects of incubation with 10 μM JTE 907 on dynamic insulin secretion, apoptosis, and β-cell proliferation by radioimmunoassay, luminescence caspase 3/7 activity, and immunofluorescence, respectively. We also measured islet IP1 and cAMP accumulation using fluorescence assays, and monitored [Ca2+]i elevations by Fura-2 single cell microfluorometry.

RESULTS

JTE 907 significantly stimulated insulin secretion from islets isolated from human donors and islets from Gpr55+/+ and Gpr55-/- mice. These stimulatory effects were accompanied by significant elevations of IP1 and [Ca2+]i, but there were no changes in cAMP generation. JTE 907 also significantly reduced cytokine-induced apoptosis in human and mouse islets and promoted human β-cell proliferation.

CONCLUSION

Our observations show for the first time that JTE 907 acts as a Gq-coupled agonist in islets to stimulate insulin secretion and maintain β-cell mass in a GPR55-independent fashion.

Cannabinoid Receptors in Metabolic Regulation and Diabetes

There is an urgent need for developing effective drugs to combat the obesity and Type 2 diabetes mellitus epidemics. The endocannabinoid system plays a major role in energy homeostasis. It comprises the cannabinoid receptors 1 and 2 (CB₁ and CB₂), endogenous ligands called endocannabinoids and their metabolizing enzymes. Because the CB₁ receptor is overactivated in metabolic alterations, pharmacological blockade of the CB₁ receptor arose as a promising candidate to treat obesity. However, because of the wide distribution of CB₁ receptors in the central nervous system, their negative central effects halted further therapeutic use. Although the CB₂ receptor is mostly peripherally expressed, its role in metabolic homeostasis remains unclear. This review discusses the potential of CB₁ and CB₂ receptors at the peripheral level to be therapeutic targets in metabolic diseases. We focus on the impact of pharmacological intervention and/or silencing on peripheral cannabinoid receptors in organs/tissues relevant for energy homeostasis. Moreover, we provide a perspective on novel therapeutic strategies modulating these receptors. Targeting CB₁ with peripherally restricted antagonists, neutral antagonists, inverse agonists, or monoclonal antibodies could represent successful strategies. CB₂ agonism has shown promising results at preclinical level. Beyond classic antagonism and agonism targeting orthosteric sites, the recently described crystal structures of CB₁ and CB₂ open new possibilities for therapeutic interventions with negative and positive allosteric modulators. The challenge of simultaneously targeting CB₁ and CB₂ might be possible by developing dual-steric ligands. The future will tell whether these promising strategies result in a renaissance of the cannabinoid receptors as therapeutic targets in metabolic diseases.

An Autonomous Cannabinoid System in Islets of Langerhans

While endocannabinoids (ECs) and cannabis were primarily studied for their nervous system effects, it is now clear that ECs are also produced in the periphery where they regulate several physiological processes, including energy storage, glucose and lipid metabolism, insulin secretion and synthesis, and hepatocyte function. Within islet of Langerhans there is an autonomous EC system (ECS). Beta (β)-cells contain all the enzymes necessary for EC synthesis and degradation; ECs are generated in response to cellular depolarization; their paracrine influence on β-cells is mostly through the cannabinoid 1 receptor (CB₁R) that is present on all β-cells; they modulate basal and glucose- and incretin-induced insulin secretion, and β-cell responses to various stressors. Furthermore, there is now accumulating evidence from preclinical studies that the autonomous islet ECS is a key player in obesity-induced inflammation in islets, and β-cell damage and apoptosis from many causes can be mitigated by CB₁R blockers. We will thoroughly review the literature relevant to the effects of ECs and their receptors on β-cells and the other cell types within islets. Therapeutic potential of agents targeting EC/CB₁R and CB₂R is highly relevant because the receptors belong to the druggable G protein-coupled receptor superfamily. Present research in the ECS must be considered preliminary, especially with regards to human islet physiology, and further research is needed in order to translate basic cellular findings into clinical practice and the use of safe, clinically approved CBR modulators with and without glucose lowering combinations presently in therapeutic use for diabetes and obesity needs to be studied.

Association Between Cannabinoid Receptor-1 Gene Polymorphism and the Risk of Diabetic Nephropathy Among Patients with Type 2 Diabetes Mellitus

Background

The cannabinoid receptor 1 (CNR1) gene polymorphism is reportedly associated with components of metabolic syndrome and coronary artery diseases in patients with type 2 diabetes mellitus (T2DM). We investigated whether the common variant rs10493353 polymorphism is associated with diabetic nephropathy (DN) in T2DM patients.

Patients and Methods

T2DM patients with DN were enrolled as a case group, and patients with only T2DM as a control group. Demographic data and biochemical parameters were collected. The polymerase chain reaction-based restriction fragment length polymorphism technique was used for genotyping. The odds ratio and 90% confidence interval were calculated to assess the association between genotypes and the risk of DN.

Results

In total, 320 T2DM patients and 320 DN patients were enrolled. Compared with T2DM patients, the DN patients have a significantly larger body mass index (BMI), longer duration of disease, and higher proportions of smokers, drinkers, and hypertension. The risk of DN was significantly decreased by genotypes AA (OR=0.39, 95% CI=0.23–0.67) and GA (OR=0.53, 95% CI=0.37–0.75) vs GG (codominant model), GA/AA vs GG (OR=0.49, 95% CI=0.35–0.67; dominant model), AA vs GG/GA (OR=0.47, 95% CI=0.28–0.80; recessive model), and the A allele (OR=0.52, 95% CI=0.40–0.68; allele model). Multiple logistic regressions still show significant levels. Negative interactions were found between gene and clinical parameters, including drinking, smoking, BMI, and hypertension.

Conclusion

The A allele of CNR1 gene rs10493353 may be a protective factor for DN in T2DM patients. The risk factors of DN can affect the protective role of A allele in the progression of DN.

The cannabinoid ligands SR141716A and AM251 enhance human and mouse islet function via GPR55-independent signalling

AIMS

Endocannabinoids are lipid mediators involved in the regulation of glucose homeostasis. They interact with the canonical cannabinoid receptors CB1 and CB2, and it is now apparent that some cannabinoid receptor ligands are also agonists at GPR55. Thus, CB1 antagonists such as SR141716A, also known as rimonabant, and AM251 act as GPR55 agonists in some cell types. The complex pharmacological properties of cannabinoids make it difficult to fully identify the relative importance of CB1 and GPR55 in the functional effects of SR141716A, and AM251. Here, we determine whether SR141716A and AM251 regulation of mouse and human islet function is through their action as GPR55 agonists.

METHODS

Islets isolated from Gpr55+/+ and Gpr55-/- mice and human donors were incubated in the absence or presence of 10 µM SR141716A or AM251, concentrations that are known to activate GPR55. Insulin secretion, cAMP, IP1, apoptosis and β-cell proliferation were quantified by standard techniques.

RESULTS

Our results provide the first evidence that SR141716A and AM251 are not GPR55 agonists in islets, as their effects are maintained in islets isolated from Gpr55-/- mice. Their signalling through Gq-coupled cascades to induce insulin secretion and human β-cell proliferation, and protect against apoptosis in vitro, indicate that they have direct beneficial effects on islet function.

CONCLUSION

These observations may be useful in directing development of peripherally restricted novel therapeutics that are structurally related to SR141716A and AM251, and which potentiate glucose-induced insulin secretion and stimulate β-cell proliferation.

Cannabinoid receptors are differentially regulated in the pancreatic islets during the early development of metabolic syndrome

The endocannabinoid system is found in tissues that regulate the glycemia, including adipose tissue, muscle, and pancreatic islets. Diet-induced metabolic syndrome changes the expression of the CB receptors in muscle, adipose tissue, and liver. However, it is poorly understood whether metabolic syndrome (MetS) affects the expression of CB receptors in pancreatic β cells. We analyzed the expression of CB receptors in pancreatic β cells under chronic high-sucrose diet (HSD)-induced MetS. Wistar rats fed an HSD as a model of MetS were used to investigate changes in cannabinoid receptors. After 8 weeks of treatment, we evaluated the appearance of the following MetS biomarkers: glucose intolerance, hyperinsulinemia, insulin resistance, hypertriglyceridemia, and an increase in visceral adiposity. To determine the presence of CB1 and CB2 receptors in pancreatic β cells, immunofluorescence of primary cell cultures and pancreatic sections was performed. For whole-islet quantification of membrane-bound CB1 and CB2 receptors, western-blotting following differential centrifugation was conducted. Our results revealed that an HSD treatment closely mimics the alterations seen in MetS. We observed that in primary cell culture, CB1 and CB2 receptors were expressed at a higher level in pancreatic β cells compared with non-β cells. MetS resulted in a reduction of CB1 in the islet, whereas abundant CB2 was observed after the treatment. CB1 and CB2 receptors are differentially expressed in pancreatic β cells during MetS development.

Cannabinoid Receptors: An Update on Cell Signaling, Pathophysiological Roles and Therapeutic Opportunities in Neurological, Cardiovascular, and Inflammatory Diseases

The identification of the human cannabinoid receptors and their roles in health and disease, has been one of the most significant biochemical and pharmacological advancements to have occurred in the past few decades. In spite of the major strides made in furthering endocannabinoid research, therapeutic exploitation of the endocannabinoid system has often been a challenging task. An impaired endocannabinoid tone often manifests as changes in expression and/or functions of type 1 and/or type 2 cannabinoid receptors. It becomes important to understand how alterations in cannabinoid receptor cellular signaling can lead to disruptions in major physiological and biological functions, as they are often associated with the pathogenesis of several neurological, cardiovascular, metabolic, and inflammatory diseases. This review focusses mostly on the pathophysiological roles of type 1 and type 2 cannabinoid receptors, and it attempts to integrate both cellular and physiological functions of the cannabinoid receptors. Apart from an updated review of pre-clinical and clinical studies, the adequacy/inadequacy of cannabinoid-based therapeutics in various pathological conditions is also highlighted. Finally, alternative strategies to modulate endocannabinoid tone, and future directions are also emphasized.

Disulfiram Treatment Normalizes Body Weight in Obese Mice

Obesity is a top public health concern, and a molecule that safely treats obesity is urgently needed. Disulfiram (known commercially as Antabuse), an FDA-approved treatment for chronic alcohol addiction, exhibits anti-inflammatory properties and helps protect against certain types of cancer. Here, we show that in mice disulfiram treatment prevented body weight gain and abrogated the adverse impact of an obesogenic diet on insulin responsiveness while mitigating liver steatosis and pancreatic islet hypertrophy. Additionally, disulfiram treatment reversed established diet-induced obesity and metabolic dysfunctions in middle-aged mice. Reductions in feeding efficiency and increases in energy expenditure were associated with body weight regulation in response to long-term disulfiram treatment. Loss of fat tissue and an increase in liver fenestrations were also observed in rats on disulfiram. Given the potent anti-obesogenic effects in rodents, repurposing disulfiram in the clinic could represent a new strategy to treat obesity and its metabolic comorbidities.

Cannabis use prevalence among individuals with diabetes: The National Survey on Drug Use and Health, 2005-2018

BACKGROUND

The aim of the current study is to estimate cannabis use prevalence among individuals with diabetes participating in the United States (US) National Survey on Drug Use and Health (NSDUH), 2005-2018. Plausible biological mechanisms link cannabis use and metabolic regulation. Cannabis use can also alter perception and adherence to treatment especially among patients with insulin-dependent diabetes.

METHODS

The NSDUH is designed to select and recruit, annually, a representative sample of the non-institutionalized US population (12+ years). Computer-assisted self-interviews gathered information on cannabis use. The current study sample included 30,915 participants who self-reported a physician diagnosis of diabetes.

RESULTS

Prevalence of past 30-day cannabis use increased 340% among individuals with diabetes, from 1.7% (95% confidence interval [CI] = 1.1, 2.6) in 2005 to 5.8% (95% CI = 4.7, 7.1) in 2018. Results from the logistic regression model indicated that this increase was robust (odds ratio of cannabis use per NSDUH year = 1.13; 95% CI = 1.10, 1.15). The increase was observed among different sociodemographic subgroups and in states with or without medical cannabis laws.

CONCLUSIONS

As cannabis use prevalence increases, screening for use among diabetes patients is needed to optimize outcomes and reduce potential adverse effects.

Maternal exposure to Δ9-tetrahydrocannabinol impairs female offspring glucose homeostasis and endocrine pancreatic development in the rat

Recent reports indicate that 7% of pregnant mothers in North America use cannabis. This is concerning given that in utero exposure to Δ9-tetrahydrocannabinol (Δ9-THC), the main psychoactive component in cannabis, causes fetal growth restriction and may alter replication and survival of pancreatic β-cells in the offspring. Accordingly, we hypothesized that maternal exposure to Δ9-THC during pregnancy would impair postnatal glucometabolic health of offspring. To test this hypothesis, pregnant Wistar rats were treated with daily intraperitoneal injections of either 3 mg/kg Δ9-THC or vehicle from gestational day 6 to birth. Offspring were subsequently challenged with glucose and insulin at 5 months of age to assess glucose tolerance and peripheral muscle insulin sensitivity. Female offspring exposed to Δ9-THC in utero were glucose intolerant, associated with blunted insulin response in muscle and increased serum insulin concentration 15 min after glucose challenge. Additionally, pancreata from male and female offspring were harvested at postnatal day 21 and 5 months of age for assessment of endocrine pancreas morphometry by immunostaining. This analysis revealed that gestational exposure to Δ9-THC reduced the density of islets in female, but not male, offspring at postnatal day 21 and 5 months, culminating in reduced β-cell mass at 5 months. These results demonstrate that fetal exposure to Δ9-THC causes female-specific impairments in glucose homeostasis, raising concern regarding the metabolic health of offspring, particularly females, exposed to cannabis in utero.

Novel CB1 receptor antagonist BAR-1 modifies pancreatic islet function and clinical parameters in prediabetic and diabetic mice

BACKGROUDS

Cannabinoid receptor antagonists have been suggested as a novel treatment for obesity and diabetes. We have developed a synthetic cannabinoid receptor antagonist denominated BAR-1. As the function and integrity of a β-cell cellular structure are important keys for diabetes onset, we evaluated the effects of pharmacological administration of BAR-1 on prediabetic and diabetic rodents.

METHODS

CD-1 mice fed a hypercaloric diet or treated with streptozotocin were treated with 10 mg/kg BAR-1 for 2, 4 or 8 weeks. Body weight, oral glucose tolerance test, HbA1c, triglycerides and insulin in serum were measured. In isolated islets, we evaluated stimulated secretion and mRNA expression, and relative area of islets in fixed pancreases. Docking analysis of BAR-1 was complemented.

RESULTS

BAR-1 treatment slowed down weight gain in prediabetic mice. Fasting glucose-insulin relation also decreased in BAR-1-treated mice and glucose-stimulated insulin secretion was increased in isolated islets, without effects in oral test. Diabetic mice treated with BAR-1 showed a reduced glucose and a partial recovery of islet integrity. Gene expression of insulin and glucagon showed biphasic behaviour, increasing after 4 weeks of BAR-1 administration; however, after 8 weeks, mRNA abundance decreased significantly. Administration of BAR-1 also prevents changes in endocannabinoid element expression observed in prediabetic mice. No changes were detected in other parameters studied, including the histological structure. A preliminary in-silico study suggests a close interaction with CB1 receptor.

CONCLUSIONS

BAR-1 induces improvement of islet function, isolated from both prediabetic and diabetic mice. Effects of BAR-1 suggest a possible interaction with other cannabinoid receptors.

Effects of oral, smoked, and vaporized cannabis on endocrine pathways related to appetite and metabolism: a randomized, double-blind, placebo-controlled, human laboratory study

As perspectives on cannabis continue to shift, understanding the physiological and behavioral effects of cannabis use is of paramount importance. Previous data suggest that cannabis use influences food intake, appetite, and metabolism, yet human research in this regard remains scant. The present study investigated the effects of cannabis administration, via different routes, on peripheral concentrations of appetitive and metabolic hormones in a sample of cannabis users. This was a randomized, crossover, double-blind, placebo-controlled study. Twenty participants underwent four experimental sessions during which oral cannabis, smoked cannabis, vaporized cannabis, or placebo was administered. Active compounds contained 6.9 ± 0.95% (~50.6 mg) ∆9-tetrahydrocannabinol (THC). Repeated blood samples were obtained, and the following endocrine markers were measured: total ghrelin, acyl-ghrelin, leptin, glucagon-like peptide-1 (GLP-1), and insulin. Results showed a significant drug main effect (p = 0.001), as well as a significant drug × time-point interaction effect (p = 0.01) on insulin. The spike in blood insulin concentrations observed under the placebo condition (probably due to the intake of brownie) was blunted by cannabis administration. A significant drug main effect (p = 0.001), as well as a trend-level drug × time-point interaction effect (p = 0.08) was also detected for GLP-1, suggesting that GLP-1 concentrations were lower under cannabis, compared to the placebo condition. Finally, a significant drug main effect (p = 0.01) was found for total ghrelin, suggesting that total ghrelin concentrations during the oral cannabis session were higher than the smoked and vaporized cannabis sessions. In conclusion, cannabis administration in this study modulated blood concentrations of some appetitive and metabolic hormones, chiefly insulin, in cannabis users. Understanding the mechanisms underpinning these effects may provide additional information on the cross-talk between cannabinoids and physiological pathways related to appetite and metabolism.

The Endocannabinoid System: A Target for Cancer Treatment

In recent years, the endocannabinoid system has received great interest as a potential therapeutic target in numerous pathological conditions. Cannabinoids have shown an anticancer potential by modulating several pathways involved in cell growth, differentiation, migration, and angiogenesis. However, the therapeutic efficacy of cannabinoids is limited to the treatment of chemotherapy-induced symptoms or cancer pain, but their use as anticancer drugs in chemotherapeutic protocols requires further investigation. In this paper, we reviewed the role of cannabinoids in the modulation of signaling mechanisms implicated in tumor progression.

Prenatal Cannabinoid Exposure: Emerging Evidence of Physiological and Neuropsychiatric Abnormalities

Clinical reports of cannabis use prevalence during pregnancy vary widely from 3% to upwards of 35% in North America; this disparity likely owing to underestimates from self-reporting in many cases. The rise in cannabis use is mirrored by increasing global legalization and the overall perceptions of safety, even during pregnancy. These trends are further compounded by a lack of evidence-based policy and guidelines for prenatal cannabis use, which has led to inconsistent messaging by healthcare providers and medically licensed cannabis dispensaries regarding prenatal cannabis use for treatment of symptoms, such as nausea. Additionally, the use of cannabis to self-medicate depression and anxiety during pregnancy is a growing medical concern. This review aims to summarize recent findings of clinical and preclinical data on neonatal outcomes, as well as long-term physiological and neurodevelopmental outcomes of prenatal cannabis exposure. Although many of the outcomes under investigation have produced mixed results, we consider these data in light of the unique challenges facing cannabis research. In particular, the limited longitudinal clinical studies available have not previously accounted for the exponential increase in (-)-Δ9- tetrahydrocannabinol (Δ9-THC; the psychoactive compound in cannabis) concentrations found in cannabis over the past two decades. Polydrug use and the long-term effects of individual cannabis constituents [Δ9-THC vs. cannabidiol (CBD)] are also understudied, along with sex-dependent outcomes. Despite these limitations, prenatal cannabis exposure has been linked to low birth weight, and emerging evidence suggests that prenatal exposure to Δ9-THC, which crosses the placenta and impacts placental development, may have wide-ranging physiological and neurodevelopmental consequences. The long-term effects of these changes require more rigorous investigation, though early reports suggest Δ9-THC increases the risk of cognitive impairment and neuropsychiatric disease, including psychosis, depression, anxiety, and sleep disorders. In light of the current trends in the perception and use of cannabis during pregnancy, we emphasize the social and medical imperative for more rigorous investigation of the long-term effects of prenatal cannabis exposure.

The Expanded Endocannabinoid System/Endocannabinoidome as a Potential Target for Treating Diabetes Mellitus

PURPOSE OF REVIEW

The endocannabinoid (eCB) system, i.e. the receptors that respond to the psychoactive component of cannabis, their endogenous ligands and the ligand metabolic enzymes, is part of a larger family of lipid signals termed the endocannabinoidome (eCBome). We summarize recent discoveries of the roles that the eCBome plays within peripheral tissues in diabetes, and how it is being targeted, in an effort to develop novel therapeutics for the treatment of this increasingly prevalent disease.

RECENT FINDINGS

As with the eCB system, many eCBome members regulate several physiological processes, including energy intake and storage, glucose and lipid metabolism and pancreatic health, which contribute to the development of type 2 diabetes (T2D). Preclinical studies increasingly support the notion that targeting the eCBome may beneficially affect T2D. The eCBome is implicated in T2D at several levels and in a variety of tissues, making this complex lipid signaling system a potential source of many potential therapeutics for the treatments for T2D.

Linoleic acid in diets of mice increases total endocannabinoid levels in bowel and liver: modification by dietary glucose

AIM

Linoleic acid (LA) is an essential fatty acid involved in the biosynthesis of arachidonic acid and prostaglandins. LA is known to induce obesity and insulin resistance. In this study, two concentrations of LA with or without added glucose (G) were fed to mice to investigate their effects on endocannabinoid (EC) biology.

MATERIALS AND METHODS

Four groups of C57BL/6 mice were provided with diets containing 1% or 8% LA with or without added G (LAG) for 8 weeks. Body weights, food intake, circulating glucose and insulin levels were measured throughout the study. Following euthanasia, plasma, bowel and hepatic ECs, monoacylglycerol lipase and fatty acid amide hydroxylase protein levels (enzymes responsible for EC degradation) and transcriptional activity of PPARα in liver were quantified. Liver was probed for evidence of insulin receptor activity perturbation.

RESULTS

Increasing dietary LA from 1% to 8% significantly increased circulating, small bowel and hepatic ECs. 1%LAG fed mice had lowest feed efficiency, and only liver levels of both ECs were reduced by addition of G. Addition of G to 1% LA diets resulted in elevated monoacylglycerol lipase and fatty acid amide hydroxylase protein levels (p < 0.001 and p < 0.001, respectively) in liver due to increased transcriptional activity of PPARα (p < 0.05). The reduced EC levels with addition of G also correlated with a measure of enhanced insulin action.

CONCLUSION

In conclusion, body weight of mice is influenced by the source of calorie intake. Furthermore, tissue EC/g are dependent on tissue-specific synthesis and degradation that are modulated by dietary LA and G which also influence food efficiency, and down-stream insulin signalling pathways. The findings could potentially be useful information for weight management efforts in humans.

Targeting GPCRs Activated by Fatty Acid-Derived Lipids in Type 2 Diabetes

G protein-coupled receptors (GPCRs) are the most intensively studied drug targets, because of their diversity, cell-specific expression, and druggable sites accessible at the cell surface. Preclinical and clinical studies suggest that targeting GPCRs activated by fatty acid-derived lipids may have potential to improve glucose homeostasis and reduce complications in patients with type 2 diabetes (T2D). Despite the discontinued development of fasiglifam (TAK-875), the first FFA1 agonist to reach late-stage clinical trials, lipid-sensing receptors remain a viable target, albeit with a need for further characterization of their binding mode, intracellular signaling, and toxicity. Herein, we analyze general discovery trends, various signaling pathways, as well as possible challenges following activation of GPCRs that have been validated clinically to control blood glucose levels.

Role of Cannabinoid Receptor Type 1 in Insulin Resistance and Its Biological Implications

Endogenous cannabinoids (ECs) are lipid-signaling molecules that specifically bind to cannabinoid receptor types 1 and 2 (CB1R and CB2R) and are highly expressed in central and many peripheral tissues under pathological conditions. Activation of hepatic CB1R is associated with obesity, insulin resistance, and impaired metabolic function, owing to increased energy intake and storage, impaired glucose and lipid metabolism, and enhanced oxidative stress and inflammatory responses. Additionally, blocking peripheral CB1R improves insulin sensitivity and glucose metabolism and also reduces hepatic steatosis and body weight in obese mice. Thus, targeting EC receptors, especially CB1R, may provide a potential therapeutic strategy against obesity and insulin resistance. There are many CB1R antagonists, including inverse agonists and natural compounds that target CB1R and can reduce body weight, adiposity, and hepatic steatosis, and those that improve insulin sensitivity and reverse leptin resistance. Recently, the use of CB1R antagonists was suspended due to adverse central effects, and this caused a major setback in the development of CB1R antagonists. Recent studies, however, have focused on development of antagonists lacking adverse effects. In this review, we detail the important role of CB1R in hepatic insulin resistance and the possible underlying mechanisms, and the therapeutic potential of CB1R targeting is also discussed.

Adverse outcome pathway of developmental neurotoxicity resulting from prenatal exposures to cannabis contaminated with organophosphate pesticide residues

There is growing concern that increased use of medical and recreational cannabis may result in increased exposure to contaminants on the cannabis, such as pesticides. Several states are moving towards implementing robust regulation of the sales, cultivation, and manufacture of cannabis products. However, there are challenges with creating health-protective regulations in an industry that, to date, has been largely unregulated. The focus of this publication is a theoretical examination of what may happen when women are exposed pre-conceptually or during pregnancy to cannabis contaminated with pesticides. We propose an adverse outcome pathway of concomitant prenatal exposure to cannabinoids and the organophosphate pesticide chlorpyrifos by curating what we consider to be the key events at the molecular, cellular, and tissue levels that result in developmental neurotoxicity. The implications of this adverse outcome pathway underscore the need to elucidate the potential developmental neurotoxicity that may result from prenatal exposure to pesticide-contaminated cannabis.

Cannabinoid Signaling in Cancer

The family of chemical structures that interact with a cannabinoid receptor are broadly termed cannabinoids. Traditionally known for their psychotropic effects and their use as palliative medicine in cancer, cannabinoids are very versatile and are known to interact with several orphan receptors besides cannabinoid receptors (CBR) in the body. Recent studies have shown that several key pathways involved in cell growth, differentiation and, even metabolism and apoptosis crosstalk with cannabinoid signaling. Several of these pathways including AKT, EGFR, and mTOR are known to contribute to tumor development and metastasis, and cannabinoids may reverse their effects, thereby by inducing apoptosis, autophagy and modulating the immune system. In this book chapter, we explore how cannabinoids regulate diverse signaling mechanisms in cancer and immune cells within the tumor microenvironment and whether they impart a therapeutic effect. We also provide some important insight into the role of cannabinoids in cellular and whole body metabolism in the context of tumor inhibition. Finally, we highlight recent and ongoing clinical trials that include cannabinoids as a therapeutic strategy and several combinational approaches towards novel therapeutic opportunities in several invasive cancer conditions.

Glucose Controls the Expression of Polypyrimidine Tract-Binding Protein 1 via the Insulin Receptor Signaling Pathway in Pancreatic β Cells

In pancreatic β cells, glucose stimulates the biosynthesis of insulin at transcriptional and post-transcriptional levels. The RNA-binding protein, polypyrimidine tract-binding protein 1 (PTBP1), also named hnRNP I, acts as a critical mediator of insulin biosynthesis through binding to the pyrimidine-rich region in the 3'-untranslated region (UTR) of insulin mRNA. However, the underlying mechanism that regulates its expression in β cells is unclear. Here, we report that glucose induces the expression of PTBP1 via the insulin receptor (IR) signaling pathway in β cells. PTBP1 is present in β cells of both mouse and monkey, where its levels are increased by glucose and insulin, but not by insulin-like growth factor 1. PTBP1 levels in immortalized β cells established from wild-type (βIRWT) mice are higher than levels in β cells established from IR-null (βIRKO) mice, and ectopic re-expression of IR-WT in βIRKO cells restored PTBP1 levels. However, PTBP1 levels were not altered in βIRKO cells transfected with IR-3YA, in which the Tyr1158/1162/1163 residues are substituted with Ala. Consistently, treatment with glucose or insulin elevated PTBP1 levels in βIRWT cells, but not in βIRKO cells. In addition, silencing Akt significantly lowered PTBP1 levels. Thus, our results identify insulin as a pivotal mediator of glucose-induced PTBP1 expression in pancreatic β cells.

Impact of maternal western diet-induced obesity on offspring mortality and peripheral endocannabinoid system in mice

Over two-thirds of adults in the United States are obese or overweight, which is largely due to chronic overconsumption of diets high in fats and sugars (i.e., Western diet). Recent studies reveal that maternal obesity may predispose offspring to development of obesity and other metabolic diseases; however, the molecular underpinnings of these outcomes are largely unknown. The endocannabinoid system is an important signaling pathway that controls feeding behavior and energy homeostasis, and its activity becomes upregulated in the upper small intestinal epithelium of Western diet-induced obese mice, which drives overeating. In the current investigation, we examined the impact of chronic maternal consumption of Western diet on the expression and function of the endocannabinoid system in several peripheral organs important for food intake and energy homeostasis in offspring. Female C57BL/6Tac mice were fed a Western diet or low-fat/no-sucrose control chow for 10 weeks, then males were introduced for mating. Dams were maintained on their respective diets through weaning of pups, at which time pups were maintained on low-fat/no-sucrose chow for 10 weeks. Neonates born from dams fed Western diet, when compared to those born from mice fed control chow, unexpectedly displayed increases in mortality that occurred exclusively within six days following birth (greater than 50% mortality). Males comprised a larger fraction of surviving offspring from obese dams. Furthermore, surviving offspring displayed transient increases in body mass for first two days post weaning, and no marked changes in feeding patterns and endocannabinoid levels in upper small intestinal epithelium, pancreas, and plasma, or in expression of key endocannabinoid system genes in the upper small intestinal epithelium and pancreas at 10 weeks post-weaning. Collectively, these results suggest that maternal diet composition greatly influences survival of neonate C57BL/6Tac mice, and that surviving offspring from dams chronically fed a Western diet do not display marked changes in body mass, eating patterns, or expression and function of the endocannabinoid system in several peripheral organs important for feeding behavior and energy homeostasis.

Anandamide Effects in a Streptozotocin-Induced Alzheimer's Disease-Like Sporadic Dementia in Rats

Alzheimer's disease (AD) is characterized by multiple cognitive deficits including memory and sensorimotor gating impairments as a result of neuronal and synaptic loss. The endocannabinoid system plays an important role in these deficits but little is known about its influence on the molecular mechanism regarding phosphorylated tau (p-tau) protein accumulation - one of the hallmarks of AD -, and on the density of synaptic proteins. Thus, the aim of this study was to investigate the preventive effects of anandamide (N-arachidonoylethanolamine, AEA) on multiple cognitive deficits and on the levels of synaptic proteins (syntaxin 1, synaptophysin and synaptosomal-associated protein, SNAP-25), cannabinoid receptor type 1 (CB₁) and molecules related to p-tau degradation machinery (heat shock protein 70, HSP70), and Bcl2-associated athanogene (BAG2) in an AD-like sporadic dementia model in rats using intracerebroventricular (icv) injection of streptozotocin (STZ). Our hypothesis is that AEA could interact with HSP70, modulating the level of p-tau and synaptic proteins, preventing STZ-induced cognitive impairments. Thirty days after receiving bilateral icv injections of AEA or STZ or both, the cognitive performance of adult male Wistar rats was evaluated in the object recognition test, by the escape latency in the elevated plus maze (EPM), by the tone and context fear conditioning as well as in prepulse inhibition tests. Subsequently, the animals were euthanized and their brains were removed for histological analysis or for protein quantification by Western Blotting. The behavioral results showed that STZ impaired recognition, plus maze and tone fear memories but did not affect contextual fear memory and prepulse inhibition. Moreover, AEA prevented recognition and non-associative emotional memory impairments induced by STZ, but did not influence tone fear conditioning. STZ increased the brain ventricular area and this enlargement was prevented by AEA. Additionally, STZ reduced the levels of p-tau (Ser199/202) and increased p-tau (Ser396), although AEA did not affect these alterations. HSP70 was found diminished only by STZ, while BAG2 levels were decreased by STZ and AEA. Synaptophysin, syntaxin and CB₁ receptor levels were reduced by STZ, but only syntaxin was recovered by AEA. Altogether, albeit AEA failed to modify some AD-like neurochemical alterations, it partially prevented STZ-induced cognitive impairments, changes in synaptic markers and ventricle enlargement. This study showed, for the first time, that the administration of an endocannabinoid can prevent AD-like effects induced by STZ, boosting further investigations about the modulation of endocannabinoid levels as a therapeutic approach for AD.

Age-Related Changes in Glucose Metabolism, Hyperglycemia, and Cardiovascular Risk

Aging and diabetes mellitus are 2 well-known risk factors for cardiovascular disease (CVD). During the past 50 years, there has been an dramatic increase in life expectancy with a simultaneous increase in the prevalence of diabetes mellitus in the older population. This large number of older individuals with diabetes mellitus is problematic given that CVD risk associated with aging and diabetes mellitus. In this review, we summarize epidemiological data relating to diabetes mellitus and CVD, with an emphasis on the aging population. We then present data on hyperglycemia as a risk factor for CVD and review the current knowledge of age-related changes in glucose metabolism. Next, we review the role of obesity in the pathogenesis of age-related glucose dysregulation, followed by a summary of the results from major randomized controlled trials that focus on cardiovascular risk reduction through glycemic control, with a special emphasis on older adults. We then conclude with our proposed model of aging that body composition changes and insulin resistance link possible dysregulation of physiological pathways leading to obesity and diabetes mellitus-both forms of accelerated aging-and risks for CVD.

Reduced expression of the RNA-binding protein HuD in pancreatic neuroendocrine tumors correlates with low p27Kip1 levels and poor prognosis

For the majority of patients diagnosed with pancreatic neuroendocrine tumors (NETs), there is significant malignant potential with a poor prognosis; however, the molecular abnormalities and pathogenesis of pancreatic NETs have not been firmly established. Here, we report that loss of expression of the RNA-binding protein HuD correlates with low p27^Kip1 (p27) levels and poor prognosis in pancreatic NETs. HuD expression was frequently lost in many human pancreatic NETs, and these pancreatic NETs showed aggressive clinicopathological phenotypes with low p27 levels, increased tumor size, higher World Health Organization grade and pT stage of the tumor, and the presence of angioinvasion. Furthermore, loss of HuD was an independent, progression-free prognostic factor in multivariate survival analysis. However, the level of HuR, a member of the same Hu protein family as HuD, was not significantly correlated with pancreatic NET size and progression. Mechanistically, HuD enhanced p27 mRNA translation by interacting with both the 5'-untranslated region (UTR) and the 3'-UTR of p27 mRNA, and consequently suppressed cell cycle progression and tumor growth. In addition, HuD competed with miR-30a-3p for binding to the 3'-UTR of p27 mRNA, suggesting an interplay between HuD and miR-30a-3p in controlling p27 translation. Our results identify HuD as a pivotal suppressor of pancreatic NET growth, and suggest that HuD has potential value as a prognostic factor of pancreatic NETs. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Endocannabinoids in the Islets of Langerhans: the ugly, the bad, and the good facts

The endocannabinoid system (ECS) regulates cellular homeostasis and whole-body metabolism. There is an autonomous ECS in the endocrine pancreas, including the cannabinoid 1 receptor (CB₁R) that is present in β-cells. Here, we discuss conflicts that have arisen with regard to the function(s) of the ECs in the endocrine pancreas and that have caused confusion when defining the role of the ECS in islets of Langerhans, especially the role(s) of CB₁R in β-cells. We also discuss the latest data published concerning the ECS in islets. CB₁R in particular is not simply a negative modulator of insulin secretion as it is also involved in intra-islet inflammation during high fat-high sugar intake and it is a negative regulator of β-cell viability and turnover. We also discuss the feasibility of using CB₁R as a target for the treatment of diabetes.

Absence of cannabinoid 1 receptor in beta cells protects against high-fat/high-sugar diet-induced beta cell dysfunction and inflammation in murine islets

AIMS/HYPOTHESIS

The cannabinoid 1 receptor (CB1R) regulates insulin sensitivity and glucose metabolism in peripheral tissues. CB1R is expressed on pancreatic beta cells and is coupled to the G protein Gαi, suggesting a negative regulation of endogenous signalling in the beta cell. Deciphering the exact function of CB1R in beta cells has been confounded by the expression of this receptor on multiple tissues involved in regulating metabolism. Thus, in models of global genetic or pharmacological CB1R blockade, it is difficult to distinguish the indirect effects of improved insulin sensitivity in peripheral tissues from the direct effects of inhibiting CB1R in beta cells per se. To assess the direct contribution of beta cell CB1R to metabolism, we designed a mouse model that allows us to determine the role of CB1R specifically in beta cells in the context of whole-body metabolism.

METHODS

We generated a beta cell specific Cnr1 (CB1R) knockout mouse (β-CB1R^-/-) to study the long-term consequences of CB1R ablation on beta cell function in adult mice. We measured beta cell function, proliferation and viability in these mice in response to a high-fat/high-sugar diet and induction of acute insulin resistance with the insulin receptor antagonist S961.

RESULTS

β-CB1R^-/- mice had increased fasting (153 ± 23% increase at 10 weeks of age) and stimulated insulin secretion and increased intra-islet cAMP levels (217 ± 33% increase at 10 weeks of age), resulting in primary hyperinsulinaemia, as well as increased beta cell viability, proliferation and islet area (1.9-fold increase at 10 weeks of age). Hyperinsulinaemia led to insulin resistance, which was aggravated by a high-fat/high-sugar diet and weight gain, although beta cells maintained their insulin secretory capacity in response to glucose. Strikingly, islets from β-CB1R^-/- mice were protected from diet-induced inflammation. Mechanistically, we show that this is a consequence of curtailment of oxidative stress and reduced activation of the NLRP3 inflammasome in beta cells.

CONCLUSIONS/INTERPRETATION

Our data demonstrate CB1R to be a negative regulator of beta cell function and a mediator of islet inflammation under conditions of metabolic stress. Our findings point to beta cell CB1R as a therapeutic target, and broaden its potential to include anti-inflammatory effects in both major forms of diabetes.

DATA AVAILABILITY

Microarray data have been deposited at GEO (GSE102027).

LH-21 and abnormal cannabidiol improve β-cell function in isolated human and mouse islets through GPR55-dependent and -independent signalling

AIMS

To examine the effects of Abn-CBD (GPR55 agonist) and LH-21 (CB1 antagonist) on human and mouse islet function, and to determine signalling via GPR55 using islets from GPR55^-/- mice.

MATERIALS AND METHODS

Islets isolated from human organ donors and mice were incubated in the absence or presence of Abn-CBD or LH-21, and insulin secretion, [Ca²⁺ ]_i, cAMP_, apoptosis, β-cell proliferation and CREB and AKT phosphorylation were examined using standard techniques.

RESULTS

Abn-CBD potentiated glucose-stimulated insulin secretion and elevated [Ca²⁺ ]_i in human islets and islets from both GPR55^+/+ and GPR55^-/- mice. LH-21 also increased insulin secretion and [Ca²⁺ ]_i in human islets and GPR55^+/+ mouse islets, but concentrations of LH-21 up to 0.1 μM were ineffective in islets from GPR55^-/- mice. Neither ligand affected basal insulin secretion or islet cAMP levels. Abn-CBD and LH-21 reduced cytokine-induced apoptosis in human islets and GPR55^+/+ mouse islets, and these effects were suppressed after GPR55 deletion. They also increased β-cell proliferation: the effects of Abn-CBD were preserved in islets from GPR55^-/- mice, while those of LH-21 were abolished. Abn-CBD and LH-21 increased AKT phosphorylation in mouse and human islets.

CONCLUSIONS

This study showed that Abn-CBD and LH-21 improve human and mouse islet β-cell function and viability. Use of islets from GPR55^-/- mice suggests that designation of Abn-CBD and LH-21 as a GPR55 agonist and a CB1 antagonist, should be revised.