School of Medical Sciences and Health Innovations Research Institute, RMIT University, Victoria, Australia.
Am J Physiol Regul Integr Comp Physiol. 2010 Mar;298(3):R799-807. doi: 10.1152/ajpregu.00558.2009. Epub 2009 Dec 30.
Increased sympathetic nerve activity is associated with obesity-related hypertension, but the underlying central neural mechanisms are not clear. We examined the role of the hypothalamic paraventricular nucleus (PVN) in the regulation of sympathetic nerve activity in rats fed a normal chow diet (controls) and rats fed a high-fat diet (36% fat) over 12 wk. The effects on blood pressure, heart rate, and lumbar sympathetic nerve activity (LSNA) induced by microinjection of the GABA(A) receptor agonist muscimol or the antagonist bicuculline were monitored in anesthetized rats. Body weight of rats fed the high-fat diet was not significantly different from controls, but a significant 80% increase in epididymal fat mass, significantly elevated fasting blood glucose, and significantly impaired glucose tolerance were observed in rats fed the high-fat diet. Resting blood pressure and heart rate were not significantly different between rats fed the high-fat diet and controls. Muscimol microinjected into the PVN elicited a greater reduction of blood pressure and LSNA in rats fed the high-fat diet than controls: -14 +/- 6 vs. -7 +/- 2 mmHg and -35 +/- 6 vs. -10 +/- 9% (P < 0.05). Microinjection of bicuculline into the PVN increased blood pressure and LSNA, but the responses were similar in rats fed the high-fat diet and controls. In conclusion, the role of the paraventricular nucleus in cardiovascular regulation can be altered by a diet high in fat, even when hypertension and obesity are absent.
交感神经活动增加与肥胖相关的高血压有关，但中枢神经机制尚不清楚。我们研究了下丘脑室旁核（PVN）在正常饮食（对照组）和高脂肪饮食（36%脂肪）喂养的大鼠中调节交感神经活动中的作用，为期 12 周。在麻醉大鼠中监测了下丘脑室旁核内注射 GABA(A)受体激动剂 muscimol 或拮抗剂 bicuculline 对血压、心率和腰交感神经活动（LSNA）的影响。高脂肪饮食喂养的大鼠体重与对照组无显著差异，但附睾脂肪质量显著增加 80%，空腹血糖显著升高，葡萄糖耐量显著受损。高脂肪饮食喂养的大鼠静息血压和心率与对照组无显著差异。与对照组相比，PVN 内注射 muscimol 可使高脂肪饮食喂养的大鼠血压和 LSNA 降低幅度更大：-14 +/- 6 对 -7 +/- 2 mmHg 和 -35 +/- 6 对 -10 +/- 9%（P < 0.05）。PVN 内注射 bicuculline 可升高血压和 LSNA，但高脂肪饮食喂养的大鼠和对照组的反应相似。总之，即使在没有高血压和肥胖的情况下，高脂肪饮食也可以改变室旁核在心血管调节中的作用。
