Effects of high‐fat diet and age on hypothalamic redox balance and central blood pressure regulation

Abstract

Hypothalamic redox signaling pathways play an important role in central blood pressure (BP) regulation. Both age and a high fat (HF) diet may increase BP by elevating central levels of reactive oxygen species. Therefore, the aim of this study was to examine the effects of both age and high fat diet on hypothalamic redox balance. Young (5 mo, n=17) and old (26 mo, n=15) male F344xBN rats were fed standard or 60% HF diet for 15 wks. Young and old rats weighed 375±10 and 531±11g respectively before diet treatment, and 468±19 and 623±16g after HF diet. Initially, HF feeding was marked by an acute drop in BP and a simultaneous increase in heart rate in both young and old groups, followed by a steady increase in BP in only the young animals. Hypothalamic expression of NAD(P)H oxidase subunit p47 decreased slightly with age, but increased significantly with HF feeding in both the young and old animals, while gp91 subunit remained unaffected by both age and diet. Levels of antioxidant enzymes CuZnSOD and catalase decreased significantly with age, with a further decline in catalase due to HF diet. In addition, 4‐HNE, a marker of lipid peroxidation, increased with age but not in response to HF diet. These results suggest that both age and HF diet play important roles in altering hypothalamic redox balance.