Arterial pressure and gene expression in the nucleus of the solitary tract in rats fed with high‐fat diet (874.4)

Abstract

The aim of this study was to evaluate the mean arterial pressure (MAP) and gene expression of components of the renin‐angiotensin system (RAS) and pro‐inflammatory cytokines in the nucleus of the solitary tract (NTS) in rats fed with high‐fat diet (HFD). Male Holtzman rats (300‐320 g, n = 6/group) were fed with either standard chow diet (SCD; 5.4% total fat) or HFD (26.4% total fat) for 3 or 6 weeks before MAP recording, baroreflex tests and brains being harvested for RT‐PCR. HFD for 3 (HFD3) or 6 weeks (HFD6) increased MAP (HFD3: 114 ± 2, vs. SCD3: 105 ± 1 mmHg; HFD6: 116 ± 2, vs. SCD6: 107 ± 1 mmHg, p < 0.05). HFD6 also impaired the baroreflex (HFD6: ‐2.27 ± 0.32, vs. SCD6: ‐2.90 ± 0.15 bpm/mmHg, p < 0.05). HFD3 increased ACE mRNA expression in the NTS (HFD3: 2.78 ± 0.33, vs. SCD3: 1.00 ± 0.26, p < 0.05), without changing the levels of AT1R, TNF‐α and IL‐6 mRNAs. Conversely, HFD6 decreased ACE mRNA levels in the NTS (HFD6: 0.27 ± 0.06, vs. SCD6: 1.11 ± 0.12, p < 0.05), and increased the levels of mRNAs for AT1R (HFD6: 2.74 ± 0.35, vs. SCD6: 1.07 ± 0.25, p < 0.05), TNF‐α (HFD6: 3.00 ± 0.90, vs. SCD6: 1.10 ± 0.17, p < 0.05) and IL‐6 (HFD6: 2.73 ± 0.76, vs. SCD6: 1.08 ± 0.10, p < 0.05) in the NTS. These results suggest that HFD may activate pro‐inflammatory cytokines and modify RAS components in the NTS, whose expression differs based on the period of the HFD. These factors may contribute to the increase in MAP and the impairment of the baroreflex produced by HFD.Grant Funding Source: CAPES, FAPESP, FAPESP/PRONEX