Characteristics of a novel vasopressin receptor in the cardiovascular system

1. 抗利尿激素（AVP）受体在大鼠脑中的亚型：高亲和力[3h]-AVP结合位点在孤束核（NTS）和后脑区（AP）均有发现。此外，我们还检测了AVP受体在NTS和ap中的亚型，结合研究表明这些区域的AVP受体为V1亚型。接下来，我们在成年大鼠的NTS和AP中检测AVP a1a和v20受体mrna。在NTS中检测到V1a和V2受体mRNA的PCR产物，而在ap中未检测到，我们不知道为什么在本研究中没有在Apa中检测到V1a受体mRNA。可能的解释是大脑中AVP受体mRNA的序列可能与外周组织中V1a受体mRNA的序列不完全一致。AVP受体在心血管调节中的作用：应用麻醉高血压大鼠，观察AVP对AP压力受体反射的调节作用。一肾一夹（1…More K1C）高血压大鼠的压力感受器反射敏感性仅在初始阶段（2周）随血压升高而升高，随后恢复到正常水平。通过向AP中微量注射V1或V2拮抗剂，可以逆转初始阶段压力感受器反射敏感性的增加，avp V2受体mRNA在此期间在AP中暂时表达。电生理研究：在体外生理实验中，我们发现了脑后皮层与脑后皮层的功能关系。在AP和/或孤立束（ST）上设置刺激电极，记录NTS神经元的峰值。大部分AP和NTS神经元表现自发放电，部分NTS神经元同时接受AP和st的神经元输入，avp对AP神经元自发放电有抑制作用（24.3%）和兴奋作用（24.7%）。其余神经元（51.3%）无影响。这些结果表明，AVP敏感神经元有两种类型，AP神经元响应内源性AVP将信息传递到NTS神经元并改变动脉压力感受反射。少

1. Vasopressin (AVP) receptor subtypes in rat brain :High-affibity [_3H]-AVP binding sites have been identified in both the nucleus tractus solitarius (NTS) and the area postrema (AP). In addition, we examined the subtype (s) of the AVP receptor in the NTS and the AP.The binding study showed that AVP receptor in these areas is the V1 subtype. Next, we tested for AVP A1a-and V20receptor mRNAs in the NTS and AP of adult rats. PCR product of the V1a and V2 receptor mRNA was detected in the NTS,but not in the AP.We do not know why V1a receptor mRNA was not detected in the Apa in this study. Possible explanations are that the sequence of the AVP receptor mRNA in the brain may not completely consistent with that of V1a receptor mRNA in peripheral tissues.2. Roles of AVP receptors in cardiovascular regulation :The role of AVP in regulation of the baroreceptor reflex in the AP was examined in anesthetized hypertensive rats. The sensitivity of the baroreceptor reflex in a one-kidney one clip (1 … More K1C) hypertensive rats was increased in only the initial stage (2 weeks), in association with increase in blood pressure, and then returned to the normal level. This increase in the sensitivity of the baroreceptor reflex in the initial stage was reversed by microinjection of a V1 or V2 antagonist into the AP.AVP V2 receptor mRNA was expressed temporarily in the AP in this period.3. Electrophysiological studies :We found the functional relationship between the area postrema and NTS in the physiological experiments in vitro. Stimulating electrodes were set on the AP and/or solitary tract (ST), and spikes were recorded from the NTS neuron. Most of neurons in the AP and NTS showed spontaneous firings, and some of neurons in the NTS received the neuronal inputs from both the AP and ST.AVP caused inhibitory (24.3%) and excitatory efects (24.7%) on sponteous firings of the of the AP neurons. The rest of neurons (51.3%) were no effect. These results suggest that there are two types of AVP sensitive neuron and that the AP neurons responding to the endogenous AVP send the information into the NTS neurons and modify arterial baroreceptor reflex. Less