Earthworm Protein Protects Vascular Endothelial Function in Spontaneously Hypertensive Rats via PI3K/Akt/Nrf2 Signaling Pathway / 中国实验方剂学杂志

ABSTRACT

ObjectiveTo observe the effect of earthworm protein on the expression of phosphatidylinositol 3-kinase/protein kinase B/nuclear factor E2-related factor 2 （PI3K/Akt/Nrf2） pathway in the aorta of spontaneously hypertensive rats （SHR） and explore mechanism of earthworm protein in treating hypertensive vascular endothelial dysfunction （VED）. MethodTen 10-week-old Wistar Kyoto （WKY） rats and fifty SHR rats were selected for a week of adaptive feeding. WKY rats were selected as the normal group， and fifty SHR rats were randomized according to body weight into model， valsartan （8×10-3 g·kg-1·d-1）， and high-， medium-， and low-dose （0.2， 0.1， 0.05 g·kg-1·d-1， respectively） earthworm protein groups. The normal and model groups were administrated with equal volume of double distilled water by gavage. During the drug intervention period， the general situations of rats in each group were observed and their blood pressure was monitored at specific time points every other week before and after administration. After 8 weeks of drug intervention， enzyme-linked immunosorbent assay was employed to measure the levels of angiotensin-Ⅱ （Ang-Ⅱ） and endothelin-1 （ET-1） in the serum of rats in each group. The corresponding kits were used to determine the levels of nitric oxide （NO）， malondialdehyde （MDA）， glutathione peroxidase （GPX）， superoxide dismutase （SOD）， and ferrous ion （Fe2+）. Hematoxylin-eosin （HE） staining was employed to observe the changes in the intima of the aorta. Fluorescence quantitative polymerase chain reaction （Real-time PCR） was employed to measure the mRNA levels of PI3K， Akt， Nrf2， heme oxygenase-1 （HO-1）， and glutathione peroxidase 4 （GPX4） in the aortic tissue. Western blotting was used to determine the protein levels of p-PI3K （Tyr467/199）， PI3K， p-Akt （Ser473）， Akt， Nrf2， HO-1， and GPX4 in the thoracic aorta. ResultCompared with the normal group， the model group had decreased body mass， increased irritability， severe endothelial damage， elevated blood pressure and serum levels of Ang-Ⅱ， ET1， MDA， and Fe2+ （P<0.01）， lowered NO level （P<0.01）， and down-regulated mRNA and protein levels of p-PI3K （Tyr467/199）， PI3K， p-Akt （Ser473）， Akt， Nrf2， HO-1， and GPX4 in the aortic tissue （P<0.01）. Compared with the model group， drug intervention caused no significant change in the body mass， calmed the rats， alleviated the endothelial damage， lowered blood pressure and serum levels of Ang-Ⅱ， ET1， MDA， and Fe2+ （P<0.01）， elevated the NO level （P<0.05）， and up-regulated the mRNA and protein levels of p-PI3K （Tyr467/199）， PI3K， p-Akt （Ser473）， Akt， Nrf2， HO-1， and GPX4 （P<0.05）. ConclusionThe earthworm protein can exert antihypertensive effects by ameliorating VED in SHR. Specifically， it may regulate the PI3K/Akt/Nrf2 signaling pathway to inhibit oxidative stress and ferroptosis.