Adrenomedullin Improves Cardiac Remodeling and Function in Obese Rats with Hypertension

Abstract

This study aimed to determine whether adrenomedullin (ADM, 7.2 μg/kg/day, ip), an important endogenous active peptide, has a protective role in cardiac remodeling and function in obesity-related hypertension (OH) rats. A high-fat diet (HFD) was used to induce OH for 20 weeks. H9c2 cells incubated with palmitate (PA, 200 μM) to mimic high free fatty acid in obesity were used as an in vitro model. In OH rats, ADM not only decreased body weight (BW) and blood pressure (BP) but also improved systemic inflammation and oxidative stress. Moreover, ADM still had a greater inhibitory effect on local inflammation and oxidative stress in the hearts of OH rats, and the same anti-inflammatory and antioxidant effects were also confirmed in PA-treated H9c2 cells. The ADM receptor antagonist or Akt inhibitor effectively attenuated the inhibitory effects of ADM on inflammation and oxidative stress in PA-stimulated H9c2 cells. Furthermore, ADM application effectively normalized heart function, and hematoxylin-eosin and Masson staining and collagen volume fraction results showed that ADM improved cardiac remodeling in hearts of OH rats. ADM attenuated cardiac inflammation and oxidative stress via the receptor-Akt pathway, which involves the improvement of cardiac remodeling and function in OH rats.

Adrenomedullin Improves Hypertension and Vascular Remodeling partly through the Receptor-Mediated AMPK Pathway in Rats with Obesity-Related Hypertension

“…The SBP of tail artery in waking state were measured by a computerized tail-cuff system (NIBP, ADInstruments, Sydney, NSW, Australia). The rat was trained for SBP detection to obtain a steady pulsation of tail artery before the formal experiment began as previously described [ 19 ]. In a rat, the obtained values were analyzed by averaging 10 measurements.…”

“…The A7r5 cells suspension (100 μL) was added into a 96-well plate and cultured in a cell incubator at 37 °C for 24 h. The effect of PA (200 μM), Ang II (10 nM) or ADM (10 nM) alone on cell viability was detected by Cell Counting Kit-8 (CCK8) cell cytotoxicity test referring to the manufacturer’s instructions as previously described [ 19 ].…”

“…Reactive oxygen species (ROS) production in aortic tissue or A7r5 cells was detected with DHE staining as previously described [ 19 ]. Briefly, the tissue sections (7 μm) or the A7r5 cells (3 × 10 5 cells/mL) in six-well plates were incubated with 10 μM DHE in PBS for 30 min in a dark and humidified container at 37 °C.…”

“…Aortic tissues or A7r5 cells were homogenized in RIPA lysis buffer. After protein quantification, equal quantities of tissues or cells protein lysates were separated by polyacrylamide gel electrophoresis (PAGE) (Bio-Rad), then were electrotransferred to a nitrocellulose membrane as previously described [ 19 ]. The membrane was incubated with the primary antibody against α-actin (1:3000), Runt-related transcription factor 2 (Runx2, 1:1000), tumor necrosis factor-α (TNF-α, 1:1000), interleukin-1β (IL-1β, 1:1000), IL6 (1:1000), NOX2 (1:1000), NOX4 (1:1000), ADM (1:1000), calcitonin receptor-like receptor (CRLR, 1:1000), receptor activity modifying protein 2 (RAMP2, 1:1000), RAMP3 (1:1000) or GAPDH (1:3000), respectively, overnight at 4 °C, then secondary antibody (horseradish peroxidase-conjugated anti-rabbit or anti-mouse) for 1 h. The polyclonal antibodies against α-actin, Runx2, ADM, CRLR, RAMP2, RAMP3, IL-1β, IL6, NOX2 and NOX4 were generated by immunizing rabbits and GAPDH monoclonal antibody was generated by immunizing mouse.…”

“…At present, the potential effects and mechanisms of ADM to treat OH, especially in blood vessels, have not been thoroughly explored. Our recent work has found that ADM could improve cardiac remodeling and function in rats with OH [ 19 ]. Therefore, it is better to explore the effects and molecular mechanisms linking ADM to vascular pathophysiology in OH, and to assess the therapeutic targets that may be of specific benefit in combating vascular diseases in OH.…”