A novel peripheral cannabinoid 1 receptor antagonist, AJ5012, improves metabolic outcomes and suppresses adipose tissue inflammation in obese mice.

The overactivity of cannabinoid 1 receptor (CB1R) is associated with obesity and type 2 diabetes. First-generation CB1R antagonists, such as rimonabant, offered therapeutic advantages for the control of obesity and related metabolic abnormalities, but their therapeutic potential was limited by undesirable neuropsychiatric side effects. Here, we evaluated AJ5012 as a novel potent peripheral CB1R antagonist and, using this antagonist, investigated the role of peripheral CB1R on adipose tissue inflammation in obese mouse models. AJ5012 had a high degree of CB1R and cannabinoid 2 receptor selectivity but a low brain:plasma concentration ratio without eliciting centrally mediated neurobehavioral effects. In diet-induced obese (DIO) mice, AJ5012 did not reduce food intake but did induce a significant weight loss, likely owing to an increased energy expenditure. It was as effective as rimonabant for the improvement of hormonal or metabolic abnormalities, glycemic control, and insulin sensitivity. The treatment of DIO and leptin receptor-deficient mice with AJ5012 also exhibited effects comparable to rimonabant for the prevention of macrophage infiltration, activation of the nucleotide-binding domain and leucine-rich repeat protein 3 inflammasome, and production of proinflammatory cytokines, which resulted in the suppression of adipose tissue inflammation. In addition to macrophage, activation of CB1R in 3T3-L1 adipocytes induced the expression of proinflammatory genes, which was fully inhibited by AJ5012. Our findings identified AJ5012 as a novel peripheral CB1R antagonist and suggest that peripheral CB1R blockade might break the links between insulin resistance and adipose tissue inflammation.-Han, J. H., Shin, H., Park, J.-Y., Rho, J. G., Son, D. H., Kim, K. W., Seong, J. K., Yoon, S.-H., Kim, W. A novel peripheral cannabinoid 1 receptor antagonist, AJ5012, improves metabolic outcomes and suppresses adipose tissue inflammation in obese mice.

L-Type Calcium Channel Blocker Enhances Cellular Delivery and Gene Silencing Potency of Cell-Penetrating Asymmetric siRNAs.

The efficient delivery of small interfering RNAs (siRNAs) to the target cells is critical for the pharmaceutical success of RNA interference (RNAi) drugs. One of the possible strategies to improve siRNA delivery is to identify auxiliary molecules that augment their cellular uptake. Herein, we performed a chemical library screening in an effort to discover small molecules that enhance the potency of cholesterol-conjugated, cell-penetrating asymmetric siRNAs (cp-asiRNAs). Interestingly, three compounds identified from the screen share a common dihydropyridine (DHP) core and function as L-type calcium channel blockers (CCBs). Using confocal microscopy and quantitative analysis of small RNAs, we demonstrated that the L-type CCBs increased the endocytic cellular uptake of cp-asiRNAs. Furthermore, these small molecules substantially improved the potency of cp-asiRNAs, not only in vitro but also in vivo on rat skin. Collectively, our study provides an alternative pharmacological approach for the identification of small molecules that potentiate the effects of therapeutic siRNAs.

Blockade of cannabinoid 1 receptor improves glucose responsiveness in pancreatic beta cells.

Cannabinoid 1 receptors (CB1Rs) are expressed in peripheral tissues, including islets of Langerhans, where their function(s) is under scrutiny. Using mouse ß-cell lines, human islets and CB1R-null (CB1R-/- ) mice, we have now investigated the role of CB1Rs in modulating ß-cell function and glucose responsiveness. Synthetic CB1R agonists diminished GLP-1-mediated cAMP accumulation and insulin secretion as well as glucose-stimulated insulin secretion in mouse ß-cell lines and human islets. In addition, silencing CB1R in mouse ß cells resulted in an increased expression of pro-insulin, glucokinase (GCK) and glucose transporter 2 (GLUT2), but this increase was lost in ß cells lacking insulin receptor. Furthermore, CB1R-/- mice had increased pro-insulin, GCK and GLUT2 expression in ß cells. Our results suggest that CB1R signalling in pancreatic islets may be harnessed to improve ß-cell glucose responsiveness and preserve their function. Thus, our findings further support that blocking peripheral CB1Rs would be beneficial to ß-cell function in type 2 diabetes.

Peripheral cannabinoid 1 receptor blockade mitigates adipose tissue inflammation via NLRP3 inflammasome in mouse models of obesity.

AIM: To analyze the metabolic parameters and adipose tissue inflammation via NLRP3 inflammasome following chronic treatment of mouse models of obesity with AJ5018 as the peripherally restricted cannabinoid 1 receptor (CB1R) antagonist. MATERIALS AND METHODS: The selectivity for CB1R over CB2R, brain/plasma concentration ratio, and centrally mediated neurobehavioural effects of AJ5018, were assessed. The long-term effects of AJ5018 and rimonabant on the metabolic parameters and adipose tissue inflammation were analyzed in diet-induced obese (DIO) mice and diabetic db/db mice. RESULTS: AJ5018 had a higher degree of selectivity for CB1R over CB2R and markedly reduced brain penetrance, as reflected by the lower brain/plasma concentration ratio and the attenuated centrally mediated neurobehavioural effects, compared with its brain-penetrant parent compound rimonabant. In DIO and db/db mice, AJ5018 exhibited comparable effects to rimonabant in improving metabolic abnormalities and suppressing macrophage infiltration into white adipose tissue, activation of the NLRP3 inflammasome, and production of proinflammatory cytokines. CONCLUSIONS: These results suggest that peripheral CB1R blockade improves obesity-induced insulin resistance by suppressing adipose tissue inflammation via the NLRP3 inflammasome.