“Endocannabinoids (eCBs) are internal lipid mediators recognized by the cannabinoid-1 and -2 receptors (CB1R and CB2R, respectively), which also mediate the different physiological effects of marijuana. The endocannabinoid system, consisting of eCBs, their receptors, and the enzymes involved in their biosynthesis and degradation, is present in a vast number of peripheral organs. In this review we describe the role of the eCB/CB1R system in modulating the metabolism in several peripheral organs. We assess how eCBs, via activating the CB1R, contribute to obesity and regulate food intake. In addition, we describe their roles in modulating liver and kidney functions, as well as bone remodeling and mass. Special importance is given to emphasizing the efficacy of the recently developed peripherally restricted CB1R antagonists, which were pre-clinically tested in the management of energy homeostasis, and in ameliorating both obesity- and diabetes-induced metabolic complications.”
“An antagonist of central cannabinoid CB1 receptors rimonabant causes weight loss in patients with obesity and metabolic syndrome, improves blood lipid parameters, increases the adiponectin level, decreases the rate of glucose and glycosylated hemoglobin in patients with diabetes mellitus type-2. However, rimonabant adverse effects include depression, anxiety, nausea, and dizziness which are apparently due to the blockade of central CB1 receptors.
In mice with a high-calorie diet, we defined that the blockade of peripheral CB1 receptors prevents obesity, steatosis of the liver, improves lipid and carbohydrate metabolism. Experimental studies suggest that peripheral CB2 receptor agonists have antiatherogenic effect. To validate the expediency of clinical research of CB2 receptor agonists in patients with atherosclerosis the comparative analysis of antiatherogenic properties of cannabinoids should be performed. In addition, experiments are needed on the combination use of cannabinoids with well-known antiatherogenic agents, such as statins.”
“Chronic GPR18 activation by its agonist abnormal cannabidiol (trans-4-[3-methyl-6-(1-methylethenyl)-2-cyclohexen-1-yl]-5-pentyl-1,3-benzenediol; abn-cbd) improves myocardial redox status and function in healthy rats.
Here, we investigated the ability of abn-cbd to alleviate diabetes-evoked cardiovascular pathology and the contribution of GPR18 to this effect.
Collectively, the current findings present evidence for abn-cbd alleviation of diabetes-evoked cardiovascular anomalies likely via GPR18 dependent restoration of cardiac adiponectin-Akt-eNOS signaling and the diminution of myocardial oxidative stress.”
“CB1 and GPR55 are GPCRs expressed by islet β-cells. Pharmacological compounds have been used to investigate their function, but off-target effects of ligands have been reported.
This study examined the effects of Abn-CBD (GPR55 agonist) and LH-21 (CB1 antagonist) on human and mouse islet function, and islets from GPR55-/- mice were used to determine signalling via GPR55.
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 following 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.
This study demonstrated 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 GPR55 agonist and CB1 antagonist, should be revised.”
“The aim of this study was to determine if chronic, low-dose administration of a nonspecific cannabinoid receptor agonist could provide cardioprotective effects in a model of type I diabetes mellitus.
Δ9-Tetrahydrocannabinol administration to diabetic animals significantly reduced blood glucose concentrations and attenuated pathological changes in serum markers of oxidative stress and lipid peroxidation. Positive changes to biochemical indices in diabetic animals conferred improvements in myocardial and vascular function.
This study demonstrates that chronic, low-dose administration of Δ9-tetrahydrocannabinol can elicit antihyperglycaemic and antioxidant effects in diabetic animals, leading to improvements in end organ function of the cardiovascular system. Implications from this study suggest that cannabinoid receptors may be a potential new target for the treatment of diabetes-induced cardiovascular disease.” https://www.ncbi.nlm.nih.gov/pubmed/29181404
“The aim of this study was to determine if a nonspecific cannabinoid receptor agonist could provide cardioprotective effects in a model of type I diabetes mellitus. Outcomes from this study indicate that THC administration to STZ improved functional parameters of cardiovascular health by reducing oxidative stress, lipid peroxidation, and blood glucose levels. These results indicate that activation of cannabinoid receptors may be a viable experimental target for the prevention of oxidative stress-induced complications in type I diabetes mellitus.” https://www.hindawi.com/journals/bmri/2017/7974149/
“Dysregulated adipocyte physiology leads to imbalanced energy storage, obesity, and associated diseases, imposing a costly burden on current health care.
Cannabinoid receptor type-1 (CB1) plays a crucial role in controlling energy metabolism through central and peripheral mechanisms.
In this work, adipocyte-specific inducible deletion of the CB1 gene (Ati-CB1-KO) was sufficient to protect adult mice from diet-induced obesity and associated metabolic alterations and to reverse the phenotype in already obese mice. Compared with controls, Ati-CB1-KO mice showed decreased body weight, reduced total adiposity, improved insulin sensitivity, enhanced energy expenditure, and fat depot-specific cellular remodeling toward lowered energy storage capacity and browning of white adipocytes. These changes were associated with an increase in alternatively activated macrophages concomitant with enhanced sympathetic tone in adipose tissue.
Remarkably, these alterations preceded the appearance of differences in body weight, highlighting the causal relation between the loss of CB1 and the triggering of metabolic reprogramming in adipose tissues. Finally, the lean phenotype of Ati-CB1-KO mice and the increase in alternatively activated macrophages in adipose tissue were also present at thermoneutral conditions.
Our data provide compelling evidence for a crosstalk among adipocytes, immune cells, and the sympathetic nervous system (SNS), wherein CB1 plays a key regulatory role.”
“In visceral obesity, an overactive endocannabinoid/CB1 receptor (CB1R) system promotes increased caloric intake and decreases energy expenditure, which are mitigated by global or peripheral CB1R blockade. In mice with diet-induced obesity (DIO), inhibition of food intake by the peripherally restricted CB1R antagonist JD5037 could be attributed to endogenous leptin due to the rapid reversal of hyperleptinemia that maintains leptin resistance, but the signaling pathway engaged by leptin has remained to be determined.
We analyzed the hypothalamic circuitry targeted by leptin following chronic treatment of DIO mice with JD5037.
Leptin treatment or an increase in endogenous leptin following fasting/refeeding induced STAT3 phosphorylation in neurons in the arcuate nucleus (ARC) in lean and JD5037-treated DIO mice, but not in vehicle-treated DIO animals. Co-localization of pSTAT3 in leptin-treated mice was significantly less common with NPY+ than with POMC+ ARC neurons. The hypophagic effect of JD5037 was absent in melanocortin-4 receptor (MC4R) deficient obese mice or DIO mice treated with a MC4R antagonist, but was maintained in NPY-/- mice kept on a high-fat diet.
Peripheral CB1R blockade in DIO restores sensitivity to endogenous leptin, which elicits hypophagia via the re-activation of melanocortin signaling in the ARC.”
“Altered glucose reabsorption via the facilitative glucose transporter 2 (GLUT2) during diabetes may lead to renal proximal tubule cell (RPTC) injury, inflammation, and interstitial fibrosis. These pathologies are also triggered by activating the cannabinoid-1 receptor (CB1R), which contributes to the development of diabetic nephropathy (DN). However, the link between CB1R and GLUT2 remains to be determined. Here, we show that chronic peripheral CB1R blockade or genetically inactivating CB1Rs in the RPTCs ameliorated diabetes-induced renal structural and functional changes, kidney inflammation, and tubulointerstitial fibrosis in mice. Inhibition of CB1R also downregulated GLUT2 expression, affected the dynamic translocation of GLUT2 to the brush border membrane of RPTCs, and reduced glucose reabsorption. Thus, targeting peripheral CB1R or inhibiting GLUT2 dynamics in RPTCs has the potential to treat and ameliorate DN. These findings may support the rationale for the clinical testing of peripherally restricted CB1R antagonists or the development of novel renal-specific GLUT2 inhibitors against DN.”
“The purpose of the review was to revisit the possibility of the endocannabinoid system being a therapeutic target for the treatment of obesity by focusing on the peripheral roles in regulating appetite and energy metabolism.
Previous studies with the global cannabinoid receptor blocker rimonabant, which has both central and peripheral properties, showed that this drug has beneficial effects on cardiometabolic function but severe adverse psychiatric side effects. Consequently, focus has shifted to peripherally restricted cannabinoid 1 (CB1) receptor blockers as possible therapeutic agents that mitigate or eliminate the untoward effects in the central nervous system.
Targeting the endocannabinoid system using novel peripheral CB1 receptor blockers with negligible penetrance across the blood-brain barrier may prove to be effective therapy for obesity and its co-morbidities.
Perhaps the future of blockers targeting CB1 receptors will be tissue-specific neutral antagonists (e.g., skeletal muscle specific to treat peripheral insulin resistance, adipocyte-specific to treat fat excess, liver-specific to treat fatty liver and hepatic insulin resistance).”