Objective: Oxytocin appears to be involved in the neuroendocrine regulation of sympathetic blood pressure (BP) homeostasis. In animals, intracerebral administration of oxytocin induces BP-relevant sympathetic activation. In humans, central nervous effects of oxytocin on BP regulation remain unclear. Intranasal administration supposedly delivers oligopeptides like oxytocin directly to the brain. We investigated the effects of intranasal oxytocin on sympathetic vascular baroreflex function in humans using microneurographic techniques. Methods: In a balanced, double-blind cross-over design oxytocin or placebo was administered intranasally to 12 lean healthy males (age 25±4 years). MSNA was assessed microneurographically before (pre), 30-45 (post-I) and 105-120 minutes (post-II) after oxytocin administration. Baroreflex was challenged via graded infusions of vasoactive drugs and correlation of BP with MSNA and heart rate (HR) defined baroreflex function. Experiments were conducted in the afternoon after a 5h fasting period. Results: After oxytocin, resting MSNA (burst rate and total activity) showed significant net-increases from pre to post-II compared to placebo (∆-increase: +4.3±1.2 (oxytocin) vs. +2.2±1.4 burst/min (placebo), ANOVA p<0.05; total activity 184±11.5% (oxytocin) vs. 121±14.3% (placebo), ANOVA; p=0.01). This was combined with a small but significant net-increase in resting diastolic BP, while systolic and mean arterial BP or HR as well as baroreflex sensitivity at vasoactive drug challenge were not altered. Conclusion: Intranasally administered oxytocin induced vasoconstrictory sympathoactivation in healthy male humans. The concomitant increase of diastolic BP was most likely attributable to increased vascular tone. This suggests oxytocin-mediated upward resetting of the vascular baroreflex setpoint at centers superordinate to the mere baroreflex-feedback-loop.

中文翻译：

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鼻内催产素对健康男性的血管张力有交感兴奋作用

目的：催产素似乎参与交感血压（BP）动态平衡的神经内分泌调节。在动物体内，催产素的脑内给药诱导与BP相关的交感神经活化。在人类中，催产素对血压调节的中枢神经作用尚不清楚。鼻内给药据说将催产素等寡肽直接递送至大脑。我们使用微神经​​图谱技术研究了鼻内催产素对人交感性血管压力反射功能的影响。方法：在平衡，双盲交叉设计中，对12例健康男性（年龄25±4岁）鼻内施用催产素或安慰剂。在施用催产素之前（之前），30-45分钟（I后）和105-120分钟（II后）对患者进行微神经影像学评估。通过分阶段输注血管活性药物以及BP与MSNA和心率（HR）定义的压力反射功能之间的相互关系来挑战压力反射。在禁食5小时后的下午进行实验。结果：催产素后，静息MSNA（爆发率和总活性）与安慰剂相比，在II前至后均显示出显着的净增加（Δ上升：+ 4.3±1.2（催产素）与+ 2.2±1.4爆发/分钟（安慰剂），ANOVA p <0.05;总活性184±11.5％（催产素）与121±14.3％（安慰剂），ANOVA; p = 0.01）。这与静息舒张压的小幅但显着的净增加相结合，而收缩压和平均动脉BP或HR以及对血管活性药物攻击的压力反射敏感性均未改变。结论：鼻内施用催产素可引起健康男性血管收缩性交感神经活化。舒张压的伴随增加最可能归因于血管张力的增加。这表明催产素介导的血管压力反射反射设定点的向上复位高于仅压力反射反射回路的中心。