Integration of Stress and Reproductive Axes by Dopamine

描述(由申请人提供)：我们的总体目标是确定压力反应系统和生殖系统是如何相互作用的。这一建议是基于我们的观察结果，即内侧不确定带(MZI)中的多巴胺神经元对循环中肾上腺类固醇水平的变化敏感。众所周知，这些神经元调节生殖和摄食行为，但之前并未与应激反应有关。然而，这些神经元被认为投射到下丘脑室旁核(PVN)中的促肾上腺皮质激素(CRH)神经元，因此能够调节下丘脑-垂体-肾上腺(HPA)轴的活动，应激时这种活动会增加。我们假设MZI多巴胺神经元的活动导致下丘脑室旁核中多巴胺的释放，这同时刺激了生殖行为，抑制了应激反应。此外，我们假设这种活性对糖皮质激素水平敏感，糖皮质激素水平在应激过程中会增加。在特定的目标一中，我们将确定MZI中的多巴胺系统转录是否受糖皮质激素的调节，如果是的话，哪些是糖皮质激素。这将通过结合激光捕获显微镜(LCM)分离MZI神经元和定量实时聚合酶链式反应(qRT-PCR)来测量肾上腺切除大鼠的多巴胺转录水平来完成。在特定的目标二，我们将确定哪些多巴胺受体在下丘脑室旁核中表达，以及如果有的话，哪些在CRH神经元上表达。这也将通过将PVN神经元的LCM与qRT-PCR相结合，然后进行双标记原位杂交来实现。在特定的目标三，我们将多巴胺激动剂注射到PVN，并确定这种操作对HPA激活的标志物，即血清促肾上腺皮质激素和皮质酮增加的影响。在这些研究中，大鼠将被插管，以便在处理或束缚压力之前向下丘脑室旁核注射。这些研究对人类健康很重要，因为它们将有助于阐明下丘脑室旁核中多巴胺活动的功能以及调节这种活动的因素。这是相关的，因为几种临床上使用的治疗精神病、性功能障碍和帕金森氏症等疾病的药物操纵着大脑中的多巴胺，而这种操纵对压力和HPA活动的后果尚不清楚。

DESCRIPTION (provided by applicant): Our overall goal is to determine how the stress response system and the reproductive system interact. This proposal is based on our observation that dopamine neurons in the medial zona incerta (MZI) are sensitive to variations in circulating adrenal steroid levels. These neurons are known to regulate reproductive and feeding behavior but have not previously been implicated in the stress response. However, these neurons are believed to project to corticotropin releasing hormone (CRH) neurons in the paraventricular nucleus of the hypothalamus (PVN) and are thus in a position to regulate hypothalamic-pituitary-adrenal (HPA) axis activity, which is increased during stress. We hypothesize that activity of MZI dopamine neurons leads to dopamine release in the PVN and that this simultaneously stimulates reproductive behavior and inhibits the stress response. Furthermore, we hypothesize that this activity is sensitive to glucocorticoid levels, which increase during stress. In specific aim one we will determine if dopamine system transcripts within the MZI are regulated by glucocorticoids and, if so, which ones. This will be accomplished by combining laser- capture microscopy (LCM), to isolate MZI neurons, with quantitative real-time PCR (qRT-PCR) to measure dopamine transcript levels in adrenalectomized rats. In specific aim two we will determine which dopamine receptors are expressed in the PVN and specifically, which, if any, are expressed on CRH neurons. This will also be accomplished by combining LCM of PVN neurons with qRT-PCR followed by double-labeled in situ hybridization. In specific aim three we will inject a dopamine agonist into the PVN and determine the effect of this manipulation on markers of HPA activation, namely, increases in serum adrenocorticotropin hormone and corticosterone. For these studies rats will be cannulated to allow injection into the PVN just prior to either handling or restraint stress. The studies are important to human health because they will help elucidate the function of dopamine activity in the PVN and the factors that regulate this activity. This is relevant because several clinically used drugs that treat conditions as varied as psychosis, sexual dysfunction and Parkinson's disease manipulate brain dopamine and the consequences of this manipulation on stress and HPA activity is not understood.