Mastication, which includes biting, is of great importance not only for the intake of food but also for the mental, physical and physiological functioning of the body. For example, biting suppresses the stress response. Although biting and nitric oxide (NO) appear to modulate brain dynamics during stress, the underlying mechanisms have not been elucidated. In this study, we examined the effect of biting during restraint stress on NO levels in the rat hypothalamus. To this end, we used NO-selective electrodes that were calibrated by electron spin resonance (ESR) spectroscopy. We implanted the electrodes and probes for perfusion of solutions into the brain of rats, near the hypothalamus. Saline containing 10 mM N-nitro-L-arginine methyl ester (L-NAME), which is one of the most commonly used inhibitors of nitric oxide synthase (NOS), was employed as the perfusate. L-NAME prevented increases in NO levels in the rat hypothalamus that were induced by restraint stress and biting. Hypothalamic NO levels in rats under restraint stress for 180 min were increased above levels observed in unrestrained control rats. The increase in hypothalamic NO (from 2.123 muM to 4.760 muM) during restraint stress was reduced after biting for 30 min. The decay rate of NO levels after biting was -0.584 pA/min (-0.071 muM/min). We conclude that: (i) it is possible to evaluate NO levels in vivo in rat brain; (ii) NO levels are increased by restraint stress; and (iii) this increase is prevented by biting behavior.

中文翻译：

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束缚压力可增加大鼠下丘脑中的一氧化氮水平，而咬伤可降低一氧化氮水平。

咀嚼，包括咬咬，不仅对于食物的摄取而且对身体的心理，生理和生理机能都非常重要。例如，咬可以抑制压力响应。尽管咬和一氧化氮（NO）似乎在压力下调节大脑动力学，但其潜在机制尚未阐明。在这项研究中，我们研究了约束应激期间咬人对大鼠下丘脑NO水平的影响。为此，我们使用了通过电子自旋共振（ESR）光谱校准的NO选择电极。我们将用于溶液灌注的电极和探针植入下丘脑附近的大鼠大脑中。含有10 mM N-硝基-L-精氨酸甲酯（L-NAME）的盐水，这是最常用的一氧化氮合酶（NOS）抑制剂之一，被用作灌流液。L-NAME可以防止束缚压力和咬人所致的大鼠下丘脑NO水平升高。在约束压力下持续180分钟的大鼠下丘脑NO水平高于未受约束的对照大鼠中观察到的水平。咬人30分钟后，在约束压力下下丘脑NO的增加（从2.123μM到4.760μM）减少了。咬伤后NO水平的衰减率为-0.584 pA / min（-0.071μM/ min）。我们得出以下结论：（i）有可能评估大鼠脑内的体内NO水平；（ii）约束压力不会增加NO水平；（iii）通过咬人行为来防止这种增加。在约束压力下持续180分钟的大鼠下丘脑NO水平高于未受约束的对照大鼠中观察到的水平。咬人30分钟后，在约束压力下下丘脑NO的增加（从2.123μM到4.760μM）减少了。咬伤后NO水平的衰减率为-0.584 pA / min（-0.071μM/ min）。我们得出以下结论：（i）有可能评估大鼠脑内的体内NO水平；（ii）约束压力不会增加NO水平；（iii）通过咬人行为来防止这种增加。在约束压力下持续180分钟的大鼠下丘脑NO水平高于未受约束的对照大鼠中观察到的水平。咬人30分钟后，在约束压力下下丘脑NO的增加（从2.123μM到4.760μM）减少了。咬伤后NO水平的衰减率为-0.584 pA / min（-0.071μM/ min）。我们得出以下结论：（i）有可能评估大鼠脑内的体内NO水平；（ii）约束压力不会增加NO水平；（iii）通过咬人行为来防止这种增加。（i）有可能评估大鼠脑内的体内NO水平；（ii）约束压力不会增加NO水平；（iii）通过咬人行为来防止这种增加。（i）有可能评估大鼠脑内的体内NO水平；（ii）约束压力不会增加NO水平；（iii）通过咬人行为来防止这种增加。