Category Archives: Diabetes

2-Arachidonoylglycerol ameliorates inflammatory stress-induced insulin resistance in cardiomyocytes.

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“Several studies have linked impaired glucose uptake and insulin resistance (IR) to functional impairment of the heart. Recently, endocannabinoids have been implicated in cardiovascular disease. However, the mechanisms involving endocannabinoid signaling, glucose uptake and IR in cardiomyocytes are understudied.

Here, we report the endocannabinoid 2-Arachidonoylglycerol (2-AG) via stimulation of cannabinoid type-1 (CB1) receptor and Ca2+/Calmodulin-dependent protein kinase β (CaMKKβ) activates AMPK leading to increased glucose uptake. Interestingly, we have observed that the mRNA expression of CB1 and CB2 receptors was decreased in diabetic mice, indicating reduced endocannabinoid signaling in diabetic heart. We further establish that TNFα induces IR in cardiomyocytes.

Treatment with 2-AG suppresses TNFα-induced pro-inflammatory markers, and improves IR and glucose uptake. Conversely, pharmacological inhibition or knockdown of AMPK attenuates the anti-inflammatory effect and reversal of IR elicited by 2-AG. Additionally, in human embryonic stem cell-derived cardiomyocytes challenged with TNFα or free fatty acid (FFA), we demonstrate that 2-AG improves insulin sensitivity and glucose uptake.

In conclusion, 2-AG abates inflammatory responses, increases glucose uptake and overcomes IR in an AMPK-dependent manner in cardiomyocytes.”

https://www.ncbi.nlm.nih.gov/pubmed/28320859

MECHANISMS IN ENDOCRINOLOGY: Endocannabinoids and metabolism: past, present and future.

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“The endocannabinoid system (ECS), including cannabinoid type 1 and type 2 receptors (CB1R and CB2R), endogenous ligands called endocannabinoids and their related enzymatic machinery, is known to have a role in the regulation of energy balance.

Past information generated on the ECS, mainly focused on the involvement of this system in the central nervous system regulation of food intake, while at the same time clinical studies pointed out the therapeutic efficacy of brain-penetrant CB1R antagonists like rimonabant for obesity and metabolic disorders.

Rimonabant was removed from the market in 2009 and its obituary written due to its psychiatric side effects. However, in the meanwhile a number of investigations had started to highlight the roles of the peripheral ECS in the regulation of metabolism, bringing up new hope that the ECS might still represent target for treatment.

Accordingly, peripherally-restricted CB1R antagonists or inverse agonists have shown to effectively reduce body weight, adiposity, insulin resistance and dyslipidemia in obese animal models.

Very recent investigations have further expanded the possible toolbox for the modulation of the ECS, by demonstrating the existence of endogenous allosteric inhibitors of CB1R, the characterization of the structure of the human CB1R, and the likely involvement of CB2R in metabolic disorders. Here we give an overview of these findings, discussing what the future may hold in the context of strategies targeting the ECS in metabolic disease.”

https://www.ncbi.nlm.nih.gov/pubmed/28246151

Effects of tetrahydrocannabinol on glucose uptake in the rat brain.

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“Δ9-Tetrahydrocannabinol (THC) is the psychoactive component of the plant Cannabis sativa and acts as a partial agonist at cannabinoid type 1 and type 2 receptors in the brain.

The goal of this study was to assess the effect of THC on the cerebral glucose uptake in the rat brain.

Low blood THC levels of <1 ng/ml corresponded to an increased glucose uptake while blood THC levels > 10 ng/ml coincided with a decreased glucose uptake. The effective concentration in this region was estimated 2.4 ng/ml.

This glucose PET study showed that stimulation of CB1 receptors by THC affects the glucose uptake in the rat brain, whereby the effect of THC is regionally different and dependent on dose – an effect that may be of relevance in behavioural studies.”

https://www.ncbi.nlm.nih.gov/pubmed/28219717

GPR55: a new promising target for metabolism?

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“GPR55 is a G-protein coupled receptor (GPCR) that has been identified as a new cannabinoid receptor. Given the wide localization of GPR55 in brain and peripheral tissues, this receptor has emerged as a regulator of multiple biological actions. Lysophosphatidylinositol (LPI) is generally accepted as the endogenous ligand of GPR55. In this review, we will focus on the role of GPR55 in energy balance and glucose metabolism. We will summarize its actions on feeding, nutrient partitioning, gastrointestinal motility and insulin secretion in preclinical models and the scarce data available in humans. The potential of GPR55 to become a new pharmaceutical target to treat obesity and type 2 diabetes, as well as the foreseeing difficulties are also discussed.”  https://www.ncbi.nlm.nih.gov/pubmed/28196832

 “GPR55 – a putative “type 3” cannabinoid receptor in inflammation.”  https://www.ncbi.nlm.nih.gov/pubmed/26669245
http://www.thctotalhealthcare.com/tag/gpr55/

The endocannabinoid system: no longer anonymous in the control of nitrergic signalling?

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“The endocannabinoid system (ECS) is a key cellular signalling system that has been implicated in the regulation of diverse cellular functions. Importantly, growing evidence suggests that the biological actions of the ECS may, in part, be mediated through its ability to regulate the production and/or release of nitric oxide, a ubiquitous bioactive molecule, which functions as a versatile signalling intermediate. Herein, we review and discuss evidence pertaining to ECS-mediated regulation of nitric oxide production, as well as the involvement of reactive nitrogen species in regulating ECS-induced signal transduction by highlighting emerging work supporting nitrergic modulation of ECS function. Importantly, the studies outlined reveal that interactions between the ECS and nitrergic signalling systems can be both stimulatory and inhibitory in nature, depending on cellular context. Moreover, such crosstalk may act to maintain proper cell function, whereas abnormalities in either system can undermine cellular homoeostasis and contribute to various pathologies associated with their dysregulation. Consequently, future studies targeting these signalling systems may provide new insights into the potential role of the ECS -: nitric oxide signalling axis in disease development and/or lead to the identification of novel therapeutic targets for the treatment of nitrosative stress-related neurological, cardiovascular, and metabolic disorders.”

https://www.ncbi.nlm.nih.gov/pubmed/28130308

Developmental Role of Macrophage Cannabinoid-1 Receptor Signaling in Type-2 Diabetes.

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“Islet inflammation promotes β-cell loss and type-2 diabetes (T2D), a process replicated in Zucker Diabetic Fatty (ZDF) rats in which β-cell loss has been linked to cannabinoid-1 receptor (CB1R)-induced pro-inflammatory signaling in macrophages infiltrating pancreatic islets.

Here, we analyzed CB1R signaling in macrophages and its developmental role in T2Dα. ZDF rats with global deletion of CB1R are protected from β-cell loss, hyperglycemia and nephropathy present in ZDF littermates.

Adoptive transfer of CB1R-/- bone marrow to ZDF rats also prevents β-cell loss and hyperglycemia, but not nephropathy. ZDF islets contain elevated levels of CB1R, IL-1β, TNF-α, the chemokine CCL2 and interferon regulatory factor-5 (IRF5), a marker of M1 inflammatory macrophage polarization.

In primary cultured rodent and human macrophages, CB1R activation increased Irf5 expression, whereas knockdown of Irf5 blunted CB1R-induced secretion of inflammatory cytokines without affecting CCL2 expression, which was p38MAPKα-dependent. Macrophage-specific in vivo knockdown of Irf5 protected ZDF rats from β-cell loss and hyperglycemia.

Thus, IRF5 is a crucial downstream mediator of diabetogenic CB1R signaling in macrophages and a potential therapeutic target.”

https://www.ncbi.nlm.nih.gov/pubmed/28082458

Cannabinoid 2 Receptor Agonist Improves Systemic Sensitivity to Insulin in High-Fat Diet/Streptozotocin-Induced Diabetic Mice.

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“The endocannabinoid signalling (ECS) system has been known to regulate glucose homeostasis.

Previous studies have suggested that the cannabinoid 2 (CB2) receptor may play a regulatory role on insulin secretion, immune modulation and insulin resistance.

Given that diabetes and insulin resistance are attributable to elevated inflammatory tone, we investigated the role of CB2 receptor on glucose tolerance and insulin sensitivity in high-fat diet (HFD)/streptozotocin (STZ)-induced mice.

Our data suggest a lipolytic role of SER601 in HFD/STZ-induced diabetic mice, which results in significant improvement of systemic insulin sensitivity.

Thus, the CB2 receptor may be considered a promising target for therapeutic development against insulin resistance and obesity-related diabetes.”

https://www.ncbi.nlm.nih.gov/pubmed/27960161

Medical Cannabis – another piece in the mosaic of autoimmunity?

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“Legalization of cannabis’ medicinal use is rapidly increasing worldwide, raising the need to evaluate medical implications of cannabis. Currently evidence supports cannabis and its active ingredients as an immune-modulating agents, affecting T-cells, B-cells, Monocytes and Microglia-cells, causing an overall reduction in pro-inflammatory cytokine expression and an increase in anti-inflammatory cytokines. Due to the supporting evidence of cannabinoids as an immune-modulating agent, research focusing on cannabinoids and autoimmunity has emerged. Several clinical trials in multiple sclerosis, inflammatory bowel disease and fibromyalgia suggest cannabis’ effectiveness as an immune-modulator. However, contradicting results and lack of large scale clinical trials obscure these results. Though lacking clinical research, in-vitro and in-vivo experiments in rheumatoid arthritis, diabetes type 1 and systemic sclerosis, demonstrate a correlation between disease activity and cannabinoids.”

https://www.ncbi.nlm.nih.gov/pubmed/27859024

Role of cannabinoid receptor 1 in human adipose tissue for lipolysis regulation and insulin resistance.

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“We recently showed that the peripheral cannabinoid receptor type 1 (CNR1) gene is upregulated by the synthetic glucocorticoid dexamethasone.

CNR1 is highly expressed in the central nervous system and has been a drug target for the treatment of obesity.

Here we explore the role of peripheral CNR1 in states of insulin resistance in human adipose tissue.

CNR1 is upregulated in states of type 2 diabetes and insulin resistance.

Furthermore, CNR1 is involved in glucocorticoid-regulated lipolysis.

Peripheral CNR1 could be an interesting drug target in type 2 diabetes and dyslipidemia.”

https://www.ncbi.nlm.nih.gov/pubmed/27858284

Cannabis Use as Risk or Protection for Type 2 Diabetes: A Longitudinal Study of 18 000 Swedish Men and Women.

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“Whether or not cannabis use may increase or decrease the risk of type 2 diabetes is not clear. We analyzed the association between cannabis and subsequent type 2 diabetes and if a potential positive or reverse association persisted after controlling for potential confounders.

In this population-based cohort study, 17,967 Swedish men and women (aged 18-84 years), who answered an extensive questionnaire in 2002 (including questions on cannabis use), were followed up for new cases of type 2 diabetes (n = 608) by questionnaire (in 2010) and in health registers during 2003-2011. Odds ratios (ORs) with 95% CIs were estimated in a multiple logistic regression analysis. Potential confounders included age, sex, BMI, physical inactivity, smoking, alcohol use, and occupational position.

Results. The crude association showed that cannabis users had a reduced risk of type 2 diabetes OR = 0.68 (95% CIs: 0.47-0.99). However, this inverse association attenuated to OR = 0.94 (95% CIs: 0.63-1.39) after adjusting for age.

Conclusions. The present study suggests that there is no association between cannabis use and subsequent type 2 diabetes after controlling for age. To make more robust conclusions prospective studies, with longer periods of follow-up and more detailed information about cannabis use, are needed.”

https://www.ncbi.nlm.nih.gov/pubmed/27843955