The Mas agonist CGEN-856S prevents Ang II induced cardiomyocyte hypertrophy via nitric oxide production.

With the previous knowledge of the cardioprotective effects of the Angiotensin-(1-7) axis, a agonist of Mas receptor has been described, the CGEN-856S. This peptide is more stable than Ang-(1-7), and has a low binding affinity to Angiotensin II receptors. Although the cardioprotective effects of CGEN-856S were previously shown in vivo, the mechanisms behind its effects are still unknown. Here, we employed a combination of molecular biology, confocal microscopy, and genetically modified mouse with Mas deletion to investigate the CGEN-856S protective signaling in cardiomyocytes. In isolated adult ventricular myocytes, CGEN-856S induced an increase in nitric oxide (NO) production which was absent in cells from Mas knockout mice. Using western blot, we observed a significant increase in phosphorylation of AKT after treatment with CGEN-856S. In addition, CGEN-856S prevented the Ang II induced hypertrophy and the nuclear translocation of GRK5 in a culture model of rat neonatal cardiomyocytes. Blockage of Mas receptor and inhibition of the NO synthase abolished the effects of CGEN-856S on Ang II treated cardiomyocytes. In conclusion, we show that CGEN-856S acting via receptor Mas induces NO raise to block Ang II induced cardiomyocyte hypertrophy. These results indicate that CGEN-856S acts very similarly to Ang-(1-7) in cardiac myocytes, highlighting its therapeutic potential for treating cardiovascular diseases.

Apelin-13 treatment enhances the stability of atherosclerotic plaques.

BACKGROUND: Apelin is an endogenous peptidergic system which modulates cardiovascular function. Recent studies pointed out a fundamental contribution of apelin on atherosclerosis development; however, such reports revealed contradictory data, and to date, it is difficult to accurately define a beneficial or deleterious role. To better understand apelin function on atherosclerosis, we aimed to investigate apelin-13 treatment effects on atherosclerotic plaques composition. DESIGN: Apolipoprotein E gene-deleted mice were fed on Western-type diet for 11 weeks. Atherosclerotic plaque formation was induced in the carotid artery by a shear stress modifier device, which exposes the same vessel to distinct patterns of shear stress enabling the formation of plaques with different composition. Mice were treated with apelin-13 (2 mg kg-1 day-1 ) or vehicle for the last 3 weeks. RESULTS: Apelin-13 treatment did not alter the lipid content of low shear stress- and oscillatory shear stress-induced plaques in the carotid. However, apelin-13 greatly ameliorated plaque stability by increasing intraplaque collagen content and reducing MMP-9 expression. Furthermore, apelin-13 decreased the infiltration of inflammatory cells (neutrophil and macrophage) and intraplaque reactive oxygen species content. Interestingly, apelin-13 treatment reduced total cholesterol, LDL levels and free fatty acid serum levels, while HDL, triglycerides serum levels were not significantly changed. CONCLUSIONS: Apelin-13 treatment for 3 weeks did not alter the lesion size, but it significantly enhanced the stable phenotype of atherosclerotic plaques and improved serum lipid profile. These results indicate that activation of apelin system decreases plaque vulnerability.

Liposome-encapsulated neuropeptides for site-specific microinjection.

This paper describes an experimental approach based on nanotechnology for assessing the chronic actions of short-lived neuropeptides at specific sites of the brain. This methodology combines the advantages of two different techniques: the microinjection of a suspension of peptide-containing liposomes into a specific site of the brain, and the use of liposomes as a local and sustained release nanosystem of the peptide.

Development of hepatorenal syndrome in bile duct ligated rats.

AIM: To evaluate in bile duct ligated rats whether there were progressive alterations of renal function without changes in histopathology. METHODS: Male Wistar rats were submitted to sham-surgery or bile duct ligation (BDL) and divided according to the post-procedure time (2, 4 and 6-wk). To determine renal function parameters, rats were placed in metabolic cages and, at the end of the experiment, blood and urine samples were obtained. Histology and hydroxyproline content were analyzed in liver and renal tissue. RESULTS: Rats with 2 wk of BDL increased free water clearance (P = 0.02), reduced urinary osmolality (P = 0.03) and serum creatinine (P = 0.01) in comparison to the sham group. In contrast, rats at 6 wk of BDL showed features of HRS, including significant increase in serum creatinine and reductions in creatinine clearance, water excretion and urinary sodium concentration. Rats with 4 wk of BDL exhibited an intermediate stage of renal dysfunction. Progressive hepatic fibrosis according to post-procedure time was confirmed by histology. The increased levels of liver hydroxyproline contrasted with the absence of structural changes in the kidney, as assessed by histology and unchanged hydroxyproline content in renal tissue. CONCLUSION: Our data show that BDL produced progressive renal dysfunction without structural changes in the kidney, characterizing HRS. The present model will be useful to understand the pathophysiology of HRS.

Novel pharmaceutical composition of bradykinin potentiating penta peptide with beta-cyclodextrin: physical-chemical characterization and anti-hypertensive evaluation.

This work describes chemical properties and anti-hypertensive activity of an oral pharmaceutical formulation obtained from the complexation of beta-cyclodextrin (beta-CD) with bradykinin potentiating penta peptide (BPP-5a) founded in the Bothrops jararaca poison. Physical chemistry characterizations were recorded in order to investigate the intermolecular interactions between species in complex. Circular dichroism data indicated conformational changes of BPP-5a upon complexation with beta-CD. ROESY and theoretical calculations showed a selective approximation of triptophan moiety into cavity of beta-CD. Isothermal titration calorimetry data indicated an exothermic formation of the complex, which is accomplished by reduction of entropy. The anti-hypertensive activity of the BPP-5a/beta-CD complex has been evaluated in spontaneous hypertensive rats, showing better results than pure BPP-5a.

A novel approach based on nanotechnology for investigating the chronic actions of short-lived peptides in specific sites of the brain.

This review presents a novel experimental approach for investigating the chronic actions of short-lived peptides in specific sites of the brain. This method combines the advantages of three different techniques: liposome encapsulation, site-specific microinjection and telemetry. First, liposomes can be designed to remain located at the injection site for a long period of time, where they protect encapsulated peptide from rapid degradation and act as a sustained-release system. Secondly, microinjection allows the administration of peptides in specific sites of the brain with minimal side effects. Finally, using telemetry, it is possible to register physiological parameters and their circadian variations in undisturbed free-moving animals for several days. Angiotensin-(1-7) and angiotensin II were used as peptide models, in order to validate the proposed method. Following the unilateral microinjection of the liposome-encapsulated peptides into the rostral ventrolateral medulla (RVLM) of Wistar rats, long-lasting cardiovascular actions were elicited, for several days. Importantly, new physiological actions of angiotensin-(1-7) at the RVLM were unmasked: modulation of the circadian rhythms of blood pressure and heart rate. It is felt that this method can be applied to a wide variety of short-lived bioactive peptides and should encounter numerous applications in the field of neurosciences.

Site-specific microinjection of liposomes into the brain for local infusion of a short-lived peptide.

The short-lived peptide, angiotensin-(1-7) (Ang-(1-7)), was encapsulated in different liposome preparations, in order to evaluate the influence of membrane fluidity, membrane surface, liposome size and dose of peptide on the cardiovascular effects of the encapsulated peptide at a specific site of the brain. These preparations were microinjected unilaterally into the rostral ventrolateral medulla (RVLM) of Wistar rats, and mean arterial blood pressure (MAP) and heart rate (HR) were registered by telemetry. Pegylated, rigid and calibrated (200 nm) liposomes, containing 50 ng of Ang-(1-7), elicited a significant increase of MAP for at least 7 days, in contrast to empty liposomes or non-pegylated liposomes. When a two-fold higher peptide dose was employed or when pegylated liposomes were used in the fluid state or uncalibrated, less pronounced pressor effects were observed. These data show that the cardiovascular responses to the microinjection of Ang-(1-7)-containing liposomes into the RVLM can be modulated through the manipulation of liposome characteristics. These results can be explained by the influence of liposome characteristics on the flux of peptide release. It is expected that this new method will encounter numerous applications in the study of the chronic actions of short-lived bioactive peptides in specific sites of the brain.