Diabetic nephropathy is a major cause of end-stage kidney disease, and overactivity of the endocannabinoid/cannabinoid 1 receptor (CB 1 R) system contributes to diabetes and its complications. Zucker diabetic fatty (ZDF) rats develop type 2 diabetic nephropathy with albuminuria, reduced glomerular filtration, activation of the reninangiotensin system (RAS), oxidative/nitrative stress, podocyte loss, and increased CB 1 R expression in glomeruli. Peripheral CB 1 R blockade initiated in the prediabetic stage prevented these changes or reversed them when animals with fully developed diabetic nephropathy were treated. Treatment of diabetic ZDF rats with losartan, an angiotensin II receptor-1 (Agtr1) antagonist, attenuated the development of nephropathy and down-regulated renal cortical CB 1 R expression, without affecting the marked hyperglycemia. In cultured human podocytes, CB 1 R and desmin gene expression were increased and podocin and nephrin content were decreased by either the CB 1 R agonist arachydonoyl-2′-chloroethylamide, angiotensin II, or high glucose, and the effects of all three were antagonized by CB 1 R blockade or siRNA-mediated knockdown of CNR1 (the cannabinoid type 1 receptor gene). We conclude that increased CB 1 R signaling in podocytes contributes to the development of diabetic nephropathy and represents a common pathway through which both hyperglycemia and increased RAS activity exert their deleterious effects, highlighting the therapeutic potential of peripheral CB 1 R blockade.iabetic nephropathy, a highly prevalent and serious complication of both type 1 and type 2 diabetes mellitus and a leading cause of renal failure, is characterized by albuminuria, decreased glomerular filtration rate (GFR), mesangial expansion, thickening of the glomerular basement membrane, and glomerular sclerosis (1). Multiple mechanisms have been implicated in the development of diabetic nephropathy, including activation of the renin-angiotensin system (RAS) (2), increase in oxidative (3) and nitrosative/nitrative stress (4), as well as an increase in local inflammation (5).The endocannabinoid system plays a well-documented role in obesity and its metabolic complications, including insulin resistance and type 2 diabetes (T2DM). Globally acting cannabinoid 1 receptor (CB 1 R) antagonists/inverse agonists improve obesity-related insulin resistance, dyslipidemia, fatty liver, and β-cell loss, and attenuate obesity-related inflammatory changes both in preclinical models of diet-induced or genetic obesity and in clinical trials in overweight subjects with metabolic syndrome (reviewed in refs. 6 and 7). Global CB 1 R blockade also has beneficial effects in mouse models of type 1 and type 2 diabetic nephropathy (8-11). However, the therapeutic development of this class of compounds has been halted because of adverse neuropsychiatric side effects in a small proportion of treated subjects (12). Recent studies in rodent models have demonstrated that peripherally restricted CB 1 R antagonists are as effective as globally acti...

Obesity-related structural and functional changes in the kidney develop early in the course of obesity and occur independently of hypertension, diabetes, and dyslipidemia. Activating the renal cannabinoid-1 receptor (CBR) induces nephropathy, whereas CBR blockade improves kidney function. Whether these effects are mediated a specific cell type within the kidney remains unknown. Here, we show that specific deletion of CBR in the renal proximal tubule cells did not protect the mice from obesity, but markedly attenuated the obesity-induced lipid accumulation in the kidney and renal dysfunction, injury, inflammation, and fibrosis. These effects associated with increased activation of liver kinase B1 and the energy sensor AMP-activated protein kinase, as well as enhanced fatty acid -oxidation. Collectively, these findings indicate that renal proximal tubule cell CBR contributes to the pathogenesis of obesity-induced renal lipotoxicity and nephropathy by regulating the liver kinase B1/AMP-activated protein kinase signaling pathway.

Niemann-Pick disease type C (NPC) is a fatal, neurodegenerative, cholesterol storage disorder. With new therapeutics in clinical trials, it is imperative to improve diagnostics and facilitate early intervention. We used metabolomic profiling to identify potential markers and discovered three unknown bile acids that were increased in plasma from NPC but not control subjects. The bile acids most elevated in the NPC subjects were identified as 3β,5α,6β-trihydroxycholanic acid and its glycine conjugate, both of which were shown to be metabolites of cholestane-3β,5α,6β-triol, an oxysterol elevated in NPC. A high-throughput, mass spectrometry-based method was developed and validated to measure the glycine-conjugated bile acid in dried blood spots. Analysis of dried blood spots from 4992 controls, 134 NPC carriers, and 44 NPC subjects provided 100% sensitivity and specificity in the study samples. Quantification of the bile acid in dried blood spots, therefore, provides the basis for a newborn screen for NPC that is ready for piloting in newborn screening programs.

ObjectiveExtreme obesity is a core phenotypic feature of Prader–Willi syndrome (PWS). Among numerous metabolic regulators, the endocannabinoid (eCB) system is critically involved in controlling feeding, body weight, and energy metabolism, and a globally acting cannabinoid-1 receptor (CB1R) blockade reverses obesity both in animals and humans. The first-in-class CB1R antagonist rimonabant proved effective in inducing weight loss in adults with PWS. However, it is no longer available for clinical use because of its centrally mediated, neuropsychiatric, adverse effects.MethodsWe studied eCB ‘tone’ in individuals with PWS and in the Magel2-null mouse model that recapitulates the major metabolic phenotypes of PWS and determined the efficacy of a peripherally restricted CB1R antagonist, JD5037 in treating obesity in these mice.ResultsIndividuals with PWS had elevated circulating levels of 2-arachidonoylglycerol and its endogenous precursor and breakdown ligand, arachidonic acid. Increased hypothalamic eCB ‘tone’, manifested by increased eCBs and upregulated CB1R, was associated with increased fat mass, reduced energy expenditure, and decreased voluntary activity in Magel2-null mice. Daily chronic treatment of obese Magel2-null mice and their littermate wild-type controls with JD5037 (3 mg/kg/d for 28 days) reduced body weight, reversed hyperphagia, and improved metabolic parameters related to their obese phenotype.ConclusionsDysregulation of the eCB/CB1R system may contribute to hyperphagia and obesity in Magel2-null mice and in individuals with PWS. Our results demonstrate that treatment with peripherally restricted CB1R antagonists may be an effective strategy for the management of severe obesity in PWS.

The adipocyte-derived hormone adiponectin promotes fatty acid oxidation and improves insulin sensitivity and thus plays a key role in the regulation of lipid and glucose metabolism and energy homeostasis. Chronic cannabinoid type 1 (CB1) receptor blockade also increases lipid oxidation and improves insulin sensitivity in obese individuals or animals, resulting in reduced cardiometabolic risk. Chronic CB1 blockade reverses the obesity-related decline in serum adiponectin levels, which has been proposed to account for the metabolic effects of CB1 antagonists. Here, we investigated the metabolic actions of the CB1 inverse agonist rimonabant in high-fat diet (HFD)-induced obese adiponectin knockout (Adipo(-/-)) mice and their wild-type littermate controls (Adipo(+/+)). HFD-induced obesity and its hormonal/metabolic consequences were indistinguishable in the two strains. Daily treatment of obese mice with rimonabant for 7 days resulted in significant and comparable reductions in body weight, serum leptin, free fatty acid, cholesterol, and triglyceride levels in the two strains. Rimonabant treatment improved glucose homeostasis and insulin sensitivity to the same extent in Adipo(+/+) and Adipo(-/-) mice, whereas it reversed the HFD-induced hepatic steatosis, fibrosis, and hepatocellular damage only in the former. The adiponectin-dependent, antisteatotic effect of rimonabant was mediated by reduced uptake and increased β-oxidation of fatty acids in the liver. We conclude that reversal of the HFD-induced hepatic steatosis and fibrosis by chronic CB1 blockade, but not the parallel reduction in adiposity and improved glycemic control, is mediated by adiponectin.

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Cadmium is an environmental pollutant and significant health hazard that is similar to the physiological metal zinc. In Caenorhabditis elegans, high zinc homeostasis is regulated by the high zinc activated nuclear receptor (HIZR-1) transcription factor. To define relationships between the responses to high zinc and cadmium, we analyzed transcription. Many genes were activated by both high zinc and cadmium, and hizr-1 was necessary for activation of a subset of these genes; in addition, many genes activated by cadmium did not require hizr-1, indicating there are at least two mechanisms of cadmium-regulated transcription. Cadmium directly bound HIZR-1, promoted nuclear accumulation of HIZR-1 in intestinal cells, and activated HIZR-1–mediated transcription via the high zinc activation (HZA) enhancer. Thus, cadmium binding promotes HIZR-1 activity, indicating that cadmium acts as a zinc mimetic to hijack the high zinc response. To elucidate the relationships between high zinc and cadmium detoxification, we analyzed genes that function in three pathways: the pcs-1/phytochelatin pathway strongly promoted cadmium resistance but not high zinc resistance, the hizr-1/HZA pathway strongly promoted high zinc resistance but not cadmium resistance, and the mek-1/sek-1/kinase signaling pathway promoted resistance to high zinc and cadmium. These studies identify resistance pathways that are specific for high zinc and cadmium, as well as a shared pathway.

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