Inhibition of cardiac PERK signaling promotes peripartum cardiac dysfunction

Peripartum cardiomyopathy (PPCM) is a life-threatening heart failure occurring in the peripartum period. Although mal-angiogenesis, induced by the 16-kDa N-terminal prolactin fragment (16 K PRL), is involved in the pathogenesis, the effect of full-length prolactin (23 K PRL) is poorly understood. We transfected neonate rat cardiomyocytes with plasmids containing 23 K PRL or 16 K PRL in vitro and found that 23 K PRL, but not 16 K PRL, upregulated protein kinase RNA-like endoplasmic reticulum kinase (PERK) signaling, and hypoxia promoted this effect. During the perinatal period, cardiomyocyte-specific PERK homogenous knockout (CM-KO) mice showed PPCM phenotypes after consecutive deliveries. Downregulation of PERK or JAK/STAT signaling and upregulation of apoptosis were observed in CM-KO mouse hearts. Moreover, in bromocriptine-treated CM-KO mice, cardiac function did not improve and cardiomyocyte apoptosis was not suppressed during the peripartum period. These results demonstrate that interaction between 23 K PRL and PERK signaling is cardioprotective during the peripartum term.

Evidence of intermediate reticular formation involvement in swallow pattern generation, recorded optically in the neonate rat sagittally sectioned hindbrain

For the first time, medullary networks that control breathing and swallow are recorded optically. Episodic swallows are induced via electrical stimulation along the dorsal medulla, in and near the NTS, during spontaneously occurring fictive respiration. These findings establish that networks regulating both orofacial behaviors and breathing are accessible for optical recording at the surface of the sagittally sectioned rodent hindbrain preparation.

Notch1–Nrf2 signaling crosstalk provides myocardial protection by reducing ROS formation

Both the Notch1 and Keap1–Nrf2 signaling pathways have cardioprotective effects, but the role of Notch1–Nrf2 crosstalk in myocardial ischemia–reperfusion injury is unclear. In this study, we established hypoxia–reoxygenation in neonate rat myocardial cells and employed γ-secretase inhibitor and curcumin to inhibit and activate the Notch1 and Keap1–Nrf2 signaling pathways, respectively. We found that the combined action of the Notch1 and Keap1–Nrf2 signaling pathways significantly increased cardiomyocyte viability, inhibited cardiomyocyte apoptosis, reduced the formation of reactive oxygen species, and increased antioxidant activities. In conclusion, these findings suggest that Notch1–Nrf2 crosstalk exerts myocardial protection by reducing the formation of reactive oxygen species.

Effect of ALDH2 on High Glucose-Induced Cardiac Fibroblast Oxidative Stress, Apoptosis, and Fibrosis

Our study aimed firstly to observe whether ALDH2 was expressed in neonate rat cardiac fibroblasts, then to investigate the effect of activation of ALDH2 on oxidative stress, apoptosis, and fibrosis when cardiac fibroblasts were subjected to high glucose intervention. Cultured cardiac fibroblasts were randomly divided into normal (NG), NG + Alda-1, high glucose (HG), HG + Alda-1, HG + Alda-1 + daidzin, HG + daidzin, and hypertonic groups. Double-label immunofluorescence staining, RT-PCR, and Western blot revealed ALDH2 was expressed in cardiac fibroblasts. Compared with NG, ALDH2 activity and protein expression were reduced, and cardiac fibroblast proliferation, ROS releasing, 4-HNE protein expression, collagen type I and III at mRNA levels, and the apoptosis rate were increased in HG group. While in HG + Alda-1 group, with the increases of ALDH2 activity and protein expression, the cardiac fibroblast proliferation and ROS releasing were decreased, and 4-HNE protein expression, collagen type I and III at mRNA levels, and apoptosis rate were reduced compared with HG group. When treated with daidzin in HG + Alda-1 group, the protective effects were inhibited. Our findings suggested that ALDH2 is expressed in neonate rat cardiac fibroblasts; activation of ALDH2 decreases the HG-induced apoptosis and fibrosis through inhibition of oxidative stress.