Darlington D N, Miyamoto M, Keil L C, Dallman M F
Department of Physiology, University of California, San Francisco 94143.
Am J Physiol. 1989 Jan;256(1 Pt 2):R112-9. doi: 10.1152/ajpregu.1989.256.1.R112.
The excitatory neurotransmitter, L-glutamate (0.5 M, pH 7.4), or the organic acid, acetate (0.5 M, pH 7.4), was microinjected (50 nl over 2 min) directly into the paraventricular nuclei (PVN) of pentobarbital sodium-anesthetized rats while arterial blood pressure and heart rate and plasma adrenocorticotropic hormone (ACTH), vasopressin, and oxytocin were measured. Activation of PVN neurons with L-glutamate led to increases in plasma ACTH, vasopressin, and oxytocin and a profound bradycardia (approximately 80 beats/min) with little change in arterial blood pressure. Microinjection of acetate had no effect on the above variables. The decrease in heart rate was shown to be dependent on the concentration of glutamate injected and the volume of injectate. The bradycardia was mediated through the autonomic nervous system because ganglionic blockade (pentolinium tartrate) eliminated the response; atropine and propranolol severely attenuated the bradycardia. The bradycardia was greatest when L-glutamate was microinjected into the caudal PVN. Injections into the rostral PVN or into nuclei surrounding the PVN led to small or nonsignificant decreases in heart rate. Focal electric stimulation (2-50 microA) of the PVN also led to decreases in heart rate and arterial blood pressure. These data suggest that activation of PVN neurons leads to the release of ACTH, vasopressin, and oxytocin from the pituitary and a bradycardia that is mediated by the autonomic nervous system.
将兴奋性神经递质L - 谷氨酸（0.5 M，pH 7.4）或有机酸醋酸盐（0.5 M，pH 7.4）微量注射（2分钟内注射50纳升）到戊巴比妥钠麻醉大鼠的室旁核（PVN）中，同时测量动脉血压、心率以及血浆促肾上腺皮质激素（ACTH）、血管加压素和催产素。用L - 谷氨酸激活PVN神经元会导致血浆ACTH、血管加压素和催产素增加，以及显著的心动过缓（约80次/分钟），而动脉血压变化不大。注射醋酸盐对上述变量无影响。心率下降显示取决于注射的谷氨酸浓度和注射体积。心动过缓是通过自主神经系统介导的，因为神经节阻断（酒石酸喷托铵）消除了该反应；阿托品和普萘洛尔严重减弱了心动过缓。当将L - 谷氨酸微量注射到PVN尾部时，心动过缓最为明显。注射到PVN头部或PVN周围的核团中会导致心率小幅下降或无显著下降。对PVN进行局部电刺激（2 - 50微安）也会导致心率和动脉血压下降。这些数据表明，PVN神经元的激活会导致垂体释放ACTH、血管加压素和催产素，并引发由自主神经系统介导的心动过缓。
