Temporal patterns of alterations in obesity index, lipid profile, renal function and blood pressure during the development of hypertension in male, but not female, rats fed a moderately high-fat diet

Fluoride-induced hypertension by regulating RhoA/ROCK pathway and phenotypic transformation of vascular smooth muscle cells: In vitro and in vivo evidence

Fluoride exposure has been implicated as a potential risk factor for hypertension, but the underlying mechanisms remain unclear. This study investigated the role of the RhoA/ROCK signaling pathway in fluoride-induced hypertension. Male Wistar rats were divided into different groups and exposed to varying concentrations of sodium fluoride (NaF) or sodium chloride (NaCl) via drinking water. The rats' blood pressure was measured, and their aortic tissue was utilized for high-throughput sequencing analysis. Additionally, rat and A7r5 cell models were established using NaF and/or Fasudil. The study evaluated the effects of fluoride exposure on blood pressure, pathological changes in the aorta, as well as the protein/mRNA expression levels of phenotypic transformation indicators (a-SMA, calp, OPN) in vascular smooth muscle cells (VSMCs), along with the RhoA/ROCK signaling pathway (RhoA, ROCK1, ROCK2, MLC/p-MLC). The results demonstrated that fluoride exposure in rats led to increased blood pressure. High-throughput sequencing analysis revealed differential gene expression associated with vascular smooth muscle contraction, with the RhoA/ROCK signaling pathway emerging as a key regulator. Pathological changes in the rat aorta, such as elastic membrane rupture and collagen fiber deposition, were observed following NaF exposure. However, fasudil, a ROCK inhibitor, mitigated these pathological changes. Both in vitro and in vivo models confirmed the activation of the RhoA/ROCK signaling pathway and the phenotypic transformation of VSMCs from a contractile to a synthetic state upon fluoride exposure. Fasudil effectively inhibited the activities of ROCK1 and ROCK2 and attenuated the phenotypic transformation of VSMCs. In conclusion, fluoride has the potential to induce hypertension through the activation of the RhoA/ROCK signaling pathway and phenotypic changes in vascular smooth muscle cells. These results provide new insights into the mechanism of fluoride-induced hypertension.

Bilateral renal denervation prevents the development of hypertension during diet-induced obesity in male rats

NEW FINDINGS

What is the central question of this study? What is the role of the renal nerves in the development of obesity, hyperlipidaemia and hypertension during the long-term feeding of a moderately high-fat diet in male obesity-prone rats? What is the main finding and its importance? The renal nerves play a prominent mediatory role, without influencing the establishment of visceral adiposity and atherogenic hyperlipidaemia, in the induction and progression of pressure natriuresis impairment and hypertension during the developmental period of diet-induced obesity.

ABSTRACT

Feeding a moderately high-fat (MHF) diet in male Sprague-Dawley rats induces obesity, pressure natriuresis impairment and hypertension. This study investigated the role of the renal nerves in the impaired pressure natriuresis and hypertension caused by feeding a MHF diet. After collecting baseline data on day 0, 12 rats remained on a low-fat diet (LF group) while the others were switched onto a MHF diet and diverged into obesity-resistant (OR) or obesity-prone (OP). After 4 weeks, half of the OR and OP rats underwent bilateral renal denervation (BRD) to generate four groups: OR, OR/BRD, OP and OP/BRD (n = 12). During 10 weeks, body weight, obesity index, systolic pressure and renal excretory function were measured regularly. After 10 weeks, renal excretory responses to acute salt loading and renal autoregulation were evaluated. The OP and OP/BRD groups had greater increases of body weight and obesity index during the dietary period compared to the other groups, and by week 10 their body weight (425.1 ± 7.2 and 411.9 ± 5.1 g) became considerably larger than that of the LF group (358.5 ± 6.2 g). Renal sodium excretion was reduced by ∼20% at week 4 in the OP and OP/BRD groups, while only the OP group had lower sodium excretion at weeks 6-8 and higher systolic pressure over weeks 5-10 than the other groups and its week 10 systolic pressure reached 138.1 ± 6.7 versus 123.6 ± 2.7 mmHg of the LF group. The OP group showed delayed renal excretory responses to salt loading with rightward and downward shifts in renal autoregulatory curves. Therefore, the renal nerves exert a main mediatory role in the development of pressure natriuresis impairment and hypertension as obesity is established due to the long-term consumption of the MHF diet in male OP rats.