Relaxin-2, a peptide hormone produced by the human body, has a wide range of impacts on various bodily systems. Serelaxin has been shown to minimize infarct size and prevent excessive scar formation in animal models of myocardial ischemia-reperfusion damage. C-chain of relaxin-2 B7-33, which is synthetically generated, phosphorylates the mitogen-activated protein of kinase extracellular signal-regulated kinases 1/2, a cognate receptor for relaxin-2, inducing signaling at the relaxin receptor 1. Researchers wanted to see how B7-33 therapy affected animals with ischemia-reperfusion damage.
The left anterior descending artery of adult male CD1 mice was ligated for 30 minutes and then either reperfused for 24 hours or 7 days. At the 24-hour mark, the infarct size was measured using cardiac tissue dyed using an echocardiographic technique. Compared to vehicles, B7-33 reduced infarct size by 21% and maintained fractional shortening by 29% (P=0.02), resulting in a substantial reduction in infarct size. Fractional shortening differed much more after 7 days after myocardial infarction, when the difference was 29% and 20%, respectively. A simulated ischemia-reperfusion damage was performed on adult cardiac primary cardiomyocytes in vitro (simulated ischemia reoxygenation). GRP78 (glucose-regulated protein), an endoplasmic reticulum stress marker, was decreased in the presence of B7-33 (50 and 100 nmol/L). When B7-33 (100 nmol/L) was added to tunicamycin (2.5 g/ml), it produced a GRP78 overexpression through extracellular signal-regulated kinase 2–dependent mechanisms. Buy B7-33 peptide if you are a researcher interested in further studying the potential benefits of this promising compound.
B7-33 reduces cardiomyocyte mortality and endoplasmic reticulum stress to protect the heart while maintaining cardiac function in mice after a heart attack using a G-protein-coupled receptor (RXFP1). The extracellular signal-regulated kinase (Erk) 1/2 pathway is activated in most cell types. Allosteric agonist ML290 biases RXFP1 toward a cGMP (as opposed to conventional cAMP) response in cardiac fibroblasts instead of the canonical response. Synthetic relaxin B-chain variant (B7-33) was recently found to activate Erk 1/2 through RXFP1-mediated activation without producing cAMP in fibroblasts in a study published in Biochemistry. Because cAMP signaling may be harmful as heart failure progresses, this new signaling paradigm holds promise. The reduction of cAMP activity generated by the 2-adrenergic receptor by -blocker medication has been proven to prevent ventricular hypertrophy, dysfunction, and fibrosis. Several techniques, including ischemia preconditioning, have been found to minimize infarct size and prevent cell death during the reperfusion phase by activating Erk 1/2. 7 Endoplasmic reticula (ER) stress contributes to the pathophysiology of ischemia-induced damage because of cell death pathways triggered by the unfolded protein response (UPR). Efficient mitogen-activated protein kinase signaling in vitro reduces inflammation in response to UPR-induced oxidative stress. Short- and long-term administration of B7 33 in the setting of MI was investigated to examine the possible interplay between B7-33–induced Erk 1/2 signaling and the UPR.
For up to a week, male CD1 mice (aged 6–8 weeks) from Charles River were kept in a temperature-controlled vivarium with access to water and food before any intervention. All studies were carried out following the National Institutes of Health’s Guidelines for the Care and Use of Laboratory Animals.