Department of Physiological Sciences, Center of Biological Sciences, State University of Londrina, PR, Brazil.
Auton Neurosci. 2012 Sep 25;170(1-2):42-7. doi: 10.1016/j.autneu.2012.07.007.
The paraventricular nucleus of hypothalamus (PVN) is a well known site of integration for autonomic and cardiovascular responses, and the glutamate neurotransmitter plays an important role. The aim of our study was to evaluate the cardiovascular parameters and autonomic modulation by means of spectral analysis after ionotropic glutamate receptor inhibition in the PVN in conscious sedentary (S) or swimming trained (ST) rats. After exercise training protocol, adult male Wistar rats, instrumented with guide cannulae to PVN and artery and vein catheters were submitted to mean arterial pressure (MAP) and heart rate (HR) recording. At baseline, physical training induced a resting bradycardia (S: 379 ± 3, ST: 349 ± 2 bpm, Pb<0.05) and promoted adaptations in HRV characterized by an increase of HF in normalized values and a decrease of LF in absolute and normalized units compared with the sedentary group. Microinjection of kynurenic acid (KYNA) in the PVN of sedentary and trained rats promoted decreases in MAP and HR, but the decrease in HR was smaller in the trained animals (ΔHRS: -48 ± 7, ST: -28 ± 4 bpm, Pb<0.05). Furthermore, the differences in baseline parameters of pulse interval, found between sedentary and trained animals, disappeared after KYNA microinjection in the PVN. Our data suggest that the cardiovascular and autonomic adaptations to the heart induced by exercise training may involve glutamatergic mechanisms in the PVN.
下丘脑室旁核（PVN）是自主和心血管反应整合的已知部位，谷氨酸神经递质起着重要作用。我们的研究目的是评估在清醒久坐（S）或游泳训练（ST）大鼠的 PVN 中离子型谷氨酸受体抑制后，通过频谱分析得到的心血管参数和自主调节。在运动训练方案后，成年雄性 Wistar 大鼠，通过引导套管植入 PVN 和动脉及静脉导管，进行平均动脉压（MAP）和心率（HR）记录。在基线时，与久坐组相比，身体训练引起静息时心动过缓（S：379 ± 3，ST：349 ± 2 bpm，Pb<0.05），并促进 HRV 的适应性改变，表现为归一化高频的增加和绝对和归一化单位中 LF 的减少。在久坐和训练大鼠的 PVN 中注射 kynurenic acid（KYNA）可降低 MAP 和 HR，但在训练动物中 HR 的降低幅度较小（ΔHRS：-48 ± 7，ST：-28 ± 4 bpm，Pb<0.05）。此外，KYNA 注射后，PVN 中久坐和训练动物之间的脉间隔基线参数的差异消失。我们的数据表明，运动训练对心脏的心血管和自主适应可能涉及 PVN 中的谷氨酸能机制。
