Role of Cannabinoid CB1 Receptor in Object Recognition Memory Impairment in Chronically Rapid Eye Movement Sleep-deprived Rats / 中国医学科学杂志(英文版)

Objective We aimed to investigate whether antagonism of the cannabinoid CB1 receptor (CB1R) could affect novel object recognition (NOR) memory in chronically rapid eye movement sleep-deprived (RSD) rats.Methods The animals were examined for recognition memory following a 7-day chronic partial RSD paradigm using the multiple platform technique. The CB1R antagonist rimonabant (1 or 3 mg/kg, i.p.) was administered either at one hour prior to the sample phase for acquisition, or immediately after the sample phase for consolidation, or at one hour before the test phase for retrieval of NOR memory. For the reconsolidation task, rimonabant was administered immediately after the second sample phase.Results The RSD episode impaired acquisition, consolidation, and retrieval, but it did not affect the reconsolidation of NOR memory. Rimonabant administration did not affect acquisition, consolidation, and reconsolidation; however, it attenuated impairment of the retrieval of NOR memory induced by chronic RSD.Conclusions These findings, along with our previous report, would seem to suggest that RSD may affect different phases of recognition memory based on its duration. Importantly, it seems that the CB1R may, at least in part, be involved in the adverse effects of chronic RSD on the retrieval, but not in the acquisition, consolidation, and reconsolidation, of NOR memory.

Cannabinoid receptor-1 antagonism: a new perspective on treating a murine schistosomal liver fibrosis model

BACKGROUND Formation of schistosomal granulomata surrounding the ova can result in schistosomiasis-associated liver fibrosis (SSLF). The current standard of treatment is praziquantel (PZQ), which cannot effectively reverse SSLF. The role of the cannabinoid (CB) receptor family in liver fibrosis has recently been highlighted. OBJECTIVES This study aimed to assess the therapeutic effect of CB1 receptor antagonism in reversing SSLF in a murine model of Schistosoma mansoni infection. METHODS One hundred male Swiss albino mice were divided equally into five groups: healthy uninfected control (group I), infected control (group II), PZQ treated (group III), rimonabant (RIM) (SR141716, a CB1 receptor antagonist)-treated (group IV) and group V was treated with combined PZQ and RIM. Liver sections were obtained for histopathological examination, alpha-1 smooth muscle actin (α-SMA) immunostaining and assessment of CB1 receptor expression using real-time polymerase chain reaction (RT-PCR). FINDINGS The most effective reduction in fibrotic marker levels and granuloma load was achieved by combined treatment with PZQ+RIM (group V): CB1 receptor expression (H = 26.612, p < 0.001), number of α-SMA-positive cells (F = 57.086, p < 0.001), % hepatic portal fibrosis (F = 42.849, p < 0.001) and number of granulomata (F = 69.088, p < 0.001). MAIN CONCLUSIONS Combining PZQ with CB1 receptor antagonists yielded the best results in reversing SSLF. To our knowledge, this is the first study to test this regimen in S. mansoni infection.

Rimonabant improves metabolic parameters partially attributed to restoration of high voltage-activated Ca2+ channels in skeletal muscle in HFD-fed mice

Cannabinoid type 1 receptor (CB1R) inhibition tends to be one of the promising strategies for the treatment of obesity and other related metabolic disorders. Although CB1R inhibition may cause adverse psychiatric effects including depression and anxiety, the investigation of the role of peripheral CB1R on weight loss and related metabolic parameters are urgently needed. We first explored the effect of rimonabant, a selective CB1R antagonist/inverse agonist, on some metabolic parameters in high fat-diet (HFD)-induced obesity in mice. Then, real-time PCR and electrophysiology were used to explore the contribution of high voltage-activated Ca2+ channels (HVACCs), especially Cav1.1, on rimonabant's effect in skeletal muscle (SM) in HFD-induced obesity. Five-week HFD feeding caused body weight gain, and decreased glucose/insulin tolerance in mice compared to those in the regular diet group (P<0.05), which was restored by rimonabant treatment compared to the HFD group (P<0.05). Interestingly, HVACCs and Cav1.1 were decreased in soleus muscle cells in the HFD group compared to the control group. Daily treatment with rimonabant for 5 weeks was shown to counter such decrease (P<0.05). Collectively, our findings provided a novel understanding for peripheral CB1R's role in the modulation of body weight and glucose homeostasis and highlight peripheral CB1R as well as Cav1.1 in the SM as potential targets for obesity treatment.

In vitro activity of a novel cannabinoid receptor l selective antagonist LMJ07 / 国际药学研究杂志

Objective: LMJ07 is a novel cannabinoid receptorl (CB1R) selective antagonist discovered by our lab. In the present study, its affinity and antagonistic activity against CB1R were evaluated at the molecular and cellular levels by receptor binding experiment, CB1R internalization experiment and by monitoring the change in cytoskeletal and intracellular signal induced by CB1R activation. Methods: With the CB1R selective antagonist rimonabant (SR141716A) as control, the affinity and selectivity of LMJ07 to CB1R and CB2R were assayed by radioligand binding assays, and the G protein-independent antagonistic activity against cannabinoid receptor (CBR) was assayed by enhanced green fluorescein protein (EGFP)-CBR internalization with hierarchiae cluscer anclysis (HCA) analysis. At the same time, we evaluated the changes in cytoskeletal and the intracellular cAMP levels in response to LMJ07 treatment in CHO-CB1 cells by Cellkey label-free assays and homogeneous time-resolved fluorescence (HTRF). Additionally, we also confirmed the CB1R antagonistic efficacy of LMJ07 by detecting the content of Ca2+ in primary cultured hippocampal neuronal cells which could express CB1R with continuous fluorescence detection technology. Results: LMJ07 is a selective CB1R antagonist with high affinity, which can selectively antagonize receptor endocytosis induced by CB1RactivationIt’s affinity and antagonistic efficacy to CB1R were equal to those of rimonabant. In CHO-CB1 cells, LMJ07 (0.01-10μmol/L)could dose-dependently inverse the change in cytoskeletal as well as the increase in intracellular cAMP induced by CBR agonist Win55212-2. In the primary cultured hippocampal neuronal cells, LMJ07 (10 nmol/L-1 μmol/L) could block the increase in [Ca2+] induced by CB1R agonist Win55212-2. Conclusion: LMJ07 is a new selective CB1R antagonist, which shows equal affinity and antagonistic activity against CB1R as the widely accepted CB1R antagonist rimonabant. In addition, the combination of high content analysis (HCS) and Cellkey label-free assay provides a better research tool for rapid and high throughput screening of novel CB1R antagonists.

A Cannabinoid Receptor Agonist N-Arachidonoyl Dopamine Inhibits Adipocyte Differentiation in Human Mesenchymal Stem Cells

Endocannabinoids can affect multiple cellular targets, such as cannabinoid (CB) receptors, transient receptor potential cation channel, subfamily V, member 1 (TRPV1) and peroxisome proliferator-activated receptor gamma (PPARgamma). The stimuli to induce adipocyte differentiation in hBM-MSCs increase the gene transcription of the CB1 receptor, TRPV1 and PPARgamma. In this study, the effects of three endocannabinoids, N-arachidonoyl ethanolamine (AEA), N-arachidonoyl dopamine (NADA) and 2-arachidonoyl glycerol (2-AG), on adipogenesis in hBM-MSCs were evaluated. The adipocyte differentiation was promoted by AEA whereas inhibited by NADA. No change was observed by the treatment of non-cytotoxic concentrations of 2-AG. The difference between AEA and NADA in the regulation of adipogenesis is associated with their effects on PPARgamma transactivation. AEA can directly activate PPARgamma. The effect of AEA on PPARgamma in hBM-MSCs may prevail over that on the CB1 receptor mediated signal transduction, giving rise to the AEA-induced promotion of adipogenesis. In contrast, NADA had no effect on the PPARgamma activity in the PPARgamma transactivation assay. The inhibitory effect of NADA on adipogenesis in hBM-MSCs was reversed not by capsazepine, a TRPV1 antagonist, but by rimonabant, a CB1 antagonist/inverse agonist. Rimonabant by itself promoted adipogenesis in hBM-MSCs, which may be interpreted as the result of the inverse agonism of the CB1 receptor. This result suggests that the constantly active CB1 receptor may contribute to suppress the adipocyte differentiation of hBM-MSCs. Therefore, the selective CB1 agonists that are unable to affect cellular PPARgamma activity inhibit adipogenesis in hBM-MSCs.

Effects of Rimonabant on Cannabinoid Receptor 1 andα-Smooth Muscle Actin in C57 Mice with Experimental Hepatic Fibrosis / 天津医药

Objective To study the effect of rimonabant, cannabinoid receptor 1(CB1) antagonist, on the expressions of CB1 andα-smooth muscle actin (α-SMA) in C57 mice with experimental hepatic fibrosis, and their mechanisms in liver fibrosis progression thereof. Methods Thirty C57 mice were randomly divided into three groups, normal control group, mod-el control group and model+rimonabant group, 10 mice for each group. The mouse model of experimental hepatic fibrosis was induced by intraperitoneal injection with 10%CCl4 for two weeks. The normal saline was delivered by gavage daily in normal control group and model control group. Rimonabant was given to mice in model+rimonabant group. Mice were sacri-ficed at the end of eight weeks. Samples of liver tissue were collected. The expressions of CB1 andα-SMA in liver tissue of mice were observed by immunohistochemical staining. The score of fibrosis stage (S) in liver tissue was also analyzed. Re-sults The positive expressions of CB1 andα-SMA and the score S were significantly higher in model control group and model+rimonabant group than those in normal control group (P<0.05). The positive expressions of CB1 andα-SMA and the score S were significantly lower in rimonabant group than those in model control group (P<0.05). There were positive corre-lations in CB1,α-SMA and S scores between normal control group, model control group and model+rimonabant group (P<0.05). Conclusion The activation of CB1 can promote the formation of liver fibrosis. The anti-fibrotic effect of rimonabant, CB1 antagonist, related with the inhibiting of the proliferation and activation of hepatic stellate cells (HSC), and the inhibit-ing of the expression of CB1.

The Pathological Processing of Endocannabinoid System on Cardiac Hypertrophy in a Experimental Rats With Chronic Intermittent Hypoxia / 中国循环杂志

Objective: To investigate the effect of endocannabinoid system on cardiac hypertrophy in experimental rats with chronic intermittent hypoxia and to study the impact of endocannabinoid antagonist, rimonabant in such pathological processing. Methods: A total of 48 male Wistar rats were divided into 6 groups. 4 and 6 weeks of Normal control group, 4 and 6 weeks of Hypoxia group, 4 and 6 weeks of Hypoxia with rimonabant intervention group. n=8 in each group. The rats were sacrificed to measure left ventricular mass index (LVMI), the myocardial cell morphological changes were observed by optical microscope, the expression of cardiac calcium/calmodulin-dependent protein kinase II (CaMKII) and cardiotrophin-1 (CT-1) were detected by immunohistochemistry at 4 and 6 weeks respectively. Results: Compared with 4 and 6 weeks of Normal control group, the LVMI, cardiac hypertrophy condition, CaMKII and CT-1 were increased in 4 and 6 weeks of Hypoxia group, all P Conclusion: The Chronic intermittent hypoxia could induce myocardial hypertrophy via endocannabinoid system disorders, such pathological processing could be reduced by rimonabant intervention.

Reduced Food Intake is the Major Contributor to the Protective Effect of Rimonabant on Islet in Established Obesity-Associated Type 2 Diabetes

PURPOSE: Although the presence of cannabinoid type 1 (CB1) receptor in islets has been reported, the major contributor to the protective effect of rimonabant on islet morphology is unknown. We determined whether the protective effect of rimonabant on pancreatic islet morphology is valid in established diabetes and also whether any effect was independent of decreased food intake. MATERIALS AND METHODS: After diabetes was confirmed, Otsuka Long-Evans Tokushima Fatty rats, aged 32 weeks, were treated with rimonabant (30 mg/kg/d, rimonabant group) for 6 weeks. Metabolic profiles and islet morphology of rats treated with rimonabant were compared with those of controls without treatment (control group), a pair-fed control group, and rats treated with rosiglitazone (4 mg/kg/d, rosiglitazone group). RESULTS: Compared to the control group, rats treated with rimonabant exhibited reduced glycated albumin levels (p<0.001), islet fibrosis (p<0.01), and improved glucose tolerance (p<0.05), with no differences from the pair-fed control group. The retroperitoneal adipose tissue mass was lower in the rimonabant group than those of the pair-fed control and rosiglitazone groups (p<0.05). Rimonabant, pair-fed control, and rosiglitazone groups showed decreased insulin resistance and increased adiponectin, with no differences between the rimonabant and pair-fed control groups. CONCLUSION: Rimonabant had a protective effect on islet morphology in vivo even in established diabetes. However, the protective effect was also reproduced by pair-feeding. Thus, the results of this study did not support the significance of islet CB1 receptors in islet protection with rimonabant in established obesity-associated type 2 diabetes.

Long-term randomized clinical trials of pharmacological treatment of obesity: systematic review

Introduction: Obesity has become a public health problem. The increment in energy intake and the reduction of caloric expenditure as a result of sedentary lifestyles promotes a positive energetic balance resulting in the increase of fat deposits. In response to this, the prescription of pharmacological treatments has also increased. Objective: To evaluate the long-term weight loss effectiveness of pharmacological treatments. Methodology: A systematic review was conducted on randomized clinical trials registered in Pub Med, Scielo, and EBSCOHOST from January 1st 1999 to December 31st 2008, including those with an intervention program with orlistat, sibutramine, and rimonabant equal or greater to two years. Two hundred and twelve articles were identified, 201 studies were excluded, and eleven were analyzed; seven from orlistat, two from sibutramine, and two from rimonabant. Information of design, intervention time, number of patients, age, body mass index and weight loss, difference between the intervention group versus the placebo, significance level, and methodological quality were obtained. Main findings: The percentage of weight loss with orlistat ranged between 5 and 12%, the mean weight loss was 8 kg, and a difference between IG vs. placebo of 3.7 kg. Weight loss with sibutramine ranged between 4 and 10%, the mean weight loss was 7.4 kg and a difference between the intervention group versus placebo was 5.5 kg. Weight loss with rimonabant was 7% with a mean weight loss of 7.3 kg, and the difference compared with the placebo was 4.4 kg. Conclusions: Weight loss with pharmacotherapy is modest; weight regain after interruption of treatment, adverse effects, costs and lack of evidence related to long-term morbi-mortality, do not justify the generalized use of pharmacological treatment of obesity.

Introducción: La obesidad se ha convertido en un problema de salud pública. El incremento en el consumo energético y el menor gasto calórico, debido al sedentarismo, promueve un balance energético positivo que se traduce en el incremento de depósitos grasos. En respuesta al incremento de la obesidad se ha aumentado la prescripción del tratamiento farmacológico. Objetivo: Evaluar la efectividad del tratamiento farmacológico sobre la pérdida de peso con un seguimiento igual o mayor a 2 años. Metodologia: Se realizó una revisión sistemática de estudios aleatorios registrados en PubMed, Scielo y EBSCOHOST del 1 enero de 1999 al 31 de diciembre del 2008 y se seleccionaron aquellos con un período de intervención mayor o igual a dos años con orlistat (Or), sibutramina (Sib) y rimonabant (Ri). Se identificaron 212 artículos, se excluyeron 201 estudios y se analizaron once, siete de Or, dos de Sib y dos de Ri. Se obtuvo información del diseño del estudio, el tiempo de intervención, el número de participantes, la edad, el índice de masa corporal (IMC), la pérdida de peso, la diferencia entre GI vs placebo, el nivel de significancia y la calidad metodológica. Hallazgos: El porcentaje de pérdida de peso al final de la intervención con orlistat osciló entre 5% y 12%, un promedio de pérdida de 8 kg y una diferencia entre GI vs placebo de 3.7 kg. Con sibutramina, entre 4% y 10%, el promedio de pérdida de peso fue de 7.4 kg y diferencia entre GI vs placebo de 5.5kg. Con rimonabant, se observó en promedio 7.3 kg de pérdida de peso a los 2 años, y una diferencia con el grupo placebo de 4.4 kg. El porcentaje de pérdida de peso fue de 7%. Conclusiones: La pérdida de peso con farmacoterapia es modesta, la recuperación posterior a la interrupción del tratamiento, los efectos adversos, el costo y la falta de evidencias sobre morbi-mortalidad a largo plazo, no justifican el tratamiento farmacológico generalizado de la obesidad.

Elevando el colesterol HDL: ¿Cuál es la mejor estrategia?: [revisão] / Raising HDL cholesterol: which is the best strategy?: [review]

Após atingir as metas para os níveis de LDL-colesterol, é imperativo alcançar a meta do HDL-colesterol, por suas conhecidas propriedades antiaterogênicas confirmadas amplamente em muitos estudos epidemiológicos. Esta revisão analisa de maneira objetiva e concisa as diversas alternativas disponíveis na prática clínica diária para aumentar os níveis de HDL-colesterol em nosoos pacientes, com o objetivo de alcançar melhores prognósticos em termos de morbimortalidade cardiovascular.

After having reached the objective for the LDL cholesterol levels, it becomes imperative to reach the objective for HDL cholesterol, known for its anti-atherogenic properties, generally confirmed in many epidemiological studies. This review deals, in a clear and concise manner, with the different alternatives available in daily clinical practice to raise the HDL cholesterol levels of patients, to achieve better outcomes in terms of morbidity and mortality in cardiovascular disease.

New and emerging drugs in type 2 diabetes / 대한내과학회지

Recent advances in understanding insulin secretion, action and signaling have led to the development of new pharmacological agents. Several new emerging drugs and drug classes for the management of diabetes are under development, including the incretin mimetic agents (exenatide, dipeptidyl peptidase 4 inhibitors, and glucagon-like peptide 1 analogues), the amylin analogue pramlintide, the cannabinoid-1 receptor antagonist rimonabant, the mixed peroxisome proliferator-activated receptor agonists muraglitazar and the inhaled insulin preparation Exubera. New drugs and technologic advances being made available will help achieve the goals of treating patients with diabetes to all the appropriate metabolic targets. Longer term studies will help providers weigh the benefits, adverse effects, cost, and unknown long-term risks of these medications.

Research progress on the antiobesity effects and mechanism of cannabinoid receptor type / 中国药理学通报

The CB1 receptor belongs to the G protein-coupled receptor families and are distributed extensively in the nervous system and peripheral tissues. Higher CB1 receptor system activity exhibits in obesity and the CB1 receptor is believed as anorexigenic receptor. It had been showed that rimonabant, a potent and selective antagonist of the CB1 receptor, has the ability to reduce body weight significantly and has been permitted to enter market for obesity therapy recently. Lots of researches have demonstratee that the initial reduction of body weight may be attributed to the severe anorexia induced by rimonabant, the following lasting effect of the drug on body weight loss might be due to an increase induced by it in energy expenditure.