We investigated the effects of chronic treatment with the CB1 receptor antagonist rimonabant (10 mg/kg/day p.o. for 10 weeks) in mice with established obesity (5-month high-fat diet). Untreated obese mice showed a weight gain of 46% (45.0 +/- 0.6 g vs. 30.8 +/- 0.5 g) compared with age-matched animals fed a standard diet. Rimonabant treatment, commencing after 5-month high-fat diet, produced a marked and sustained decrease in body weight (34.5 +/- 0.8 g vs. 47.2 +/- 0.5 g in the high-fat vehicle group, p < 0.001). The anti-obesity effect of rimonabant was similar to that obtained by switching obese mice from high-fat diet to standard laboratory diet during 10 weeks (final weight 33.7 +/- 0.6 g) and was associated with only transient (14 days) reduction in energy intake. Serum leptin, insulin and glucose levels were markedly elevated in obese animals. Rimonabant treatment significantly reduced these elevations (leptin -81%, insulin -78%, glucose -67%, p < 0.001 in all cases vs. high-fat vehicle group). In addition, rimonabant treatment modestly but significantly increased serum adiponectin levels (+18%, p < 0.05 vs. high-fat vehicle group). Obese mice demonstrated abnormal serum lipid profiles. Although rimonabant did not modify high-density lipoprotein cholesterol (HDLc) and had modest effects on total cholesterol, it significantly reduced triglycerides and low-density lipoprotein cholesterol (LDLc) and, notably, increased the HDLc/LDLc ratio (12.4 +/- 0.8 vs. 7.9 +/- 0.2 in high-fat vehicle group, p < 0.001). Therefore, in a model of established obesity, chronic rimonabant treatment produces a marked and sustained decrease in body weight (equivalent to that achieved by dietary change) which is associated with favourable modifications in serum biochemical and lipid profiles.

Background-Ca2ϩ release from the sarcoplasmic reticulum via the ryanodine receptor (RyR2) activates cardiac myocyte contraction. An important regulator of RyR2 function is FKBP12.6, which stabilizes RyR2 in the closed state during diastole. ␤-Adrenergic stimulation has been suggested to dissociate FKBP12.6 from RyR2, leading to diastolic sarcoplasmic reticulum Ca 2ϩ leakage and ventricular tachycardia (VT). We tested the hypothesis that FKBP12.6 overexpression in cardiac myocytes can reduce susceptibility to VT in stress conditions. Methods and Results-We developed a mouse model with conditional cardiac-specific overexpression of FKBP12.6.Transgenic mouse hearts showed a marked increase in FKBP12.6 binding to RyR2 compared with controls both at baseline and on isoproterenol stimulation (0.2 mg/kg IP). After pretreatment with isoproterenol, burst pacing induced VT in 10 of 23 control mice but in only 1 of 14 transgenic mice (PϽ0.05). In isolated transgenic myocytes, Ca 2ϩ spark frequency was reduced by 50% (PϽ0.01), a reduction that persisted under isoproterenol stimulation, whereas the sarcoplasmic reticulum Ca 2ϩ load remained unchanged. In parallel, peak I Ca,L density decreased by 15% (PϽ0.01), and the Ca 2ϩ transient peak amplitude decreased by 30% (PϽ0.001). A 33.5% prolongation of the caffeine-evoked Ca 2ϩ transient decay was associated with an 18% reduction in the Na ϩ -Ca 2ϩ exchanger protein level (PϽ0.05). Conclusions-Increased FKBP12.6 binding to RyR2 prevents triggered VT in normal hearts in stress conditions, probably by reducing diastolic sarcoplasmic reticulum Ca 2ϩ leak. This indicates that the FKBP12.6-RyR2 complex is an important candidate target for pharmacological prevention of VT.

Hepatitis B Virus (HBV) persists in infected hepatocytes as an episomal covalently-closed-circular DNA mini-chromosome, called cccDNA. As the main nuclear transcription template, HBV cccDNA is a key replication intermediate in the viral life cycle. Little is known about the mechanisms involved in its formation, maintenance and fate under antiviral therapies. This is mainly due to the lack of small immune-competent animal models able to recapitulate the entire HBV replication cycle, including formation of HBV cccDNA. Here we report that HBV cccDNA can be detected by Southern blot analyses in the liver of C57BL6 mice transduced with AAV-HBV. HBV cccDNA persists in the liver of these animals together with the AAV-HBV episome. We also set up a PCR strategy to distinguish the HBV cccDNA from the AAV-HBV episome. These suggest that the AAV-HBV/mouse model might be relevant to test drugs targeting HBV cccDNA regulation and persistence.