Joint Graduate Program in Physiological Sciences, PIPGCF UFSCar/UNESP, São Carlos/SP, Brazil.
Department of Biological Sciences, School of Sciences, 28108São Paulo State University (Unesp), Bauru/SP, Brazil.
J Cardiovasc Pharmacol Ther. 2021 Mar;26(2):189-199. doi: 10.1177/1074248420953271. Epub 2020 Aug 28.
Dexamethasone (DEX)-induced hypertension and cardiac remodeling are still unclear, especially in spontaneously hypertensive rats (SHR). On the other side, exercise training is a good strategy to control hypertension. Therefore, this study investigated the effects of DEX treatment and physical training on arterial pressure and cardiac remodeling in SHR.
SHR underwent treadmill training (5 days/week, 1h/session, at 50-60% of maximal capacity, 0% degree, 75 days) and received low-dose of DEX (50µg/kg, ) during the last 15 days. Sedentary Wistar rats (W) were used as control. Echocardiography and artery catheterization were performed for cardiac remodeling and function, arterial pressure and autonomic nervous system analyses. In addition, left ventricle (LV) capillary density, myocyte diameter and collagen deposition area were analyzed using specific histological staining.
Low-dose of DEX treatment did not exacerbate arterial pressure of SHR and trained groups had lower values, regardless of DEX. DEX and training decreased relative left ventricle wall thickness (RWT) and determined LV angiogenesis (+19%) and lower collagen deposition area (-22%). In addition, it determined increased left ventricular diastolic diameter. These changes were followed by improvements on systolic and diastolic function, since it was observed increased posterior wall shortening velocity (PWSV) and reduced isovolumetric relaxation time (IVRT).
In conclusion, this study is unique to indicate that low-dose of DEX treatment does not exacerbate arterial pressure in SHR and, when associated with training, it improves LV systolic and diastolic function, which may be due to LV angiogenesis and reduction of wall collagen deposition area.
地塞米松（DEX）引起的高血压和心脏重构仍不清楚，尤其是在自发性高血压大鼠（SHR）中。另一方面，运动训练是控制高血压的一种很好的策略。因此，本研究探讨了 DEX 治疗和身体训练对 SHR 动脉压和心脏重构的影响。
SHR 进行了跑步机训练（每周 5 天，每次 1 小时，最大能力的 50-60%，0%坡度，75 天），并在最后 15 天接受低剂量 DEX（50µg/kg，）。未训练的 Wistar 大鼠（W）作为对照。进行超声心动图和动脉导管插入术以分析心脏重构和功能、动脉压和自主神经系统。此外，使用特定的组织学染色分析左心室（LV）毛细血管密度、心肌细胞直径和胶原沉积面积。
低剂量 DEX 治疗并未加重 SHR 和训练组的动脉压，无论是否使用 DEX，训练组的动脉压均较低。DEX 和训练降低了相对左心室壁厚度（RWT），并确定了 LV 血管生成（增加 19%）和胶原沉积面积降低（减少 22%）。此外，它还确定了左心室舒张直径的增加。这些变化伴随着收缩和舒张功能的改善，因为观察到后壁缩短速度（PWSV）增加和等容舒张时间（IVRT）缩短。
总之，本研究的独特之处在于表明低剂量 DEX 治疗不会加重 SHR 的动脉压，并且当与训练结合使用时，它可以改善 LV 的收缩和舒张功能，这可能是由于 LV 血管生成和壁胶原沉积面积减少所致。
