Sex Differences in the Neurobiological Significance of Orexin Stress Signaling

最近的荟萃分析表明，男性和女性的神经回路受到压力的影响并不相同。 暴露，使得女性明显有更高的心理障碍发生率，而男性更高 自杀率。与应激反应相关的遗传标记，以基线方式表达 杏仁核(BLA)和前额叶皮质(PFC)可能有助于解释女性和男性的差异。这个 初步(PRL)PFC支配表达Rspo2基因的前BLA(ABLA)中的特定细胞 标记，形成一个支持应力的回路。还存在连接下臂(IL)PFC的并行抗应激电路 携带DRD1遗传标记的神经元，到表达Ppp1r1b的后部BLA(PBLA)细胞。这两个 微电路产生可变的应激响应性，当有利于预应激PRL-ABLA/Rsp2活性时， 会导致过度的应激反应，并可能导致情绪性心理障碍。这些 微电路通过Orx1和Orx2受体亚型被增食欲素/下克隆素(Orx)调制， 特异性地定位于前应激(PRL-ABLA/Rsp2 Orx1)和抗应激(IL/DRD1-pBLA/Ppp1r1b Orx2) 这个电路的元件。BLA Orx1和Orx2受体的激活在功能上也是相反的，并且 差异触发增强或抑制应激反应。这些数据表明， Orx1和Orx2刺激的电路控制压力响应性的输出。女性已经提升了 Orx2受体的表达。重点是确定这些活动之间的平衡 两个微回路，以及应激反应的性别差异，是由Orx2反义核酸的密度决定的。 应激受体，以及存在哪些特定的分子级联。我们建议研究分子 出现在Orx2受体激活下游的系统，由此降低了应激反应，在 两种稳定的表型：表现出增强恐惧条件反射的应激反应个体和个体 表现出积极避免压力的人。目的1：BLA和PFC Orx2受体将PLC修饰为mTOR信号转导通路。 由Orx2触发的细胞内分子信号通路PLC或mTOR决定了 结果。利用激光显微切割技术检测PLC和mTOR转录本和蛋白质 标记的细胞特异性PRL-ABLA/Rsp2前应激和IL/DRD1-pBLA/Ppp1r1b抗应激微电路将 允许表型、性别和电路水平的激活差异。另一种将产生的分子变化 应激反应的性别差异是Orx2活动相应地增加了可用的数量 Orx2受体。目的2：BLA Orx2受体表达上调降低应激反应 女性与男性的比较。我们假设女性和男性之间的差异源于分子 增加Orx2受体的作用，这些受体被战略性地放置来抑制促应激通路，特别是在 表现出增强恐惧条件反射的个体。多变的分子级联与细胞外信号的上调 Orx2受体可能产生更强的抗应激微电路活性，并降低应激反应性。

Recent metanalyses suggest that neurocircuits in males and females are not equally affected by stress exposure, such that females have demonstrably higher rates of psychological disorders, and males, higher rates of suicide. Genetic markers associated with stress responsiveness, expressed in basolateral amygdala (BLA) and prefrontal cortex (PFC), may help explain differences in females and males. The prelimbic (PrL) PFC innervates specific cells in the anterior BLA (aBLA) expressing the Rspo2 genetic marker, forming a pro-stress circuit. A parallel anti-stress circuit also exists connecting infralimbic (IL) PFC neurons carrying the Drd1 genetic marker, to posterior BLA (pBLA) cells that express Ppp1r1b. These two microcircuits produce variable stress responsivity, that when favoring pro-stress PrL-aBLA/Rspo2 activity, results in exaggerated stress reactivity and potentially leads to affective psychological disorders. These microcircuits are modulated by orexins/hypocretins (Orx) by means of Orx1 and Orx2 receptor subtypes, specifically localized to pro-stress (PrL-aBLA/Rspo2 Orx1) and anti-stress (IL/Drd1-pBLA/Ppp1r1b Orx2) elements of this circuitry. Activation of BLA Orx1 and Orx2 receptors are also functionally opposed, and differentially trigger enhanced or inhibited stress responsiveness. The data suggest that interplay between Orx1- and Orx2-stimulated circuits control the output of stress responsivity. Females have elevated expression of Orx2 receptors. The focus is to determine whether the balance between activation of these two microcircuits, and the sexual differences in stress responsivity, is governed by density of Orx2 anti- stress receptors and which specific molecular cascades are present. We propose to examine the molecular systems that appear downstream of Orx2 receptor activation, by which stress responsivity is reduced, in two stable phenotypes: stress-reactive individuals that exhibit enhanced fear conditioning, and individuals that exhibit active avoidance of stress. Aim 1: BLA and PFC Orx2 receptors modify PLC to mToR signaling. The intracellular molecular signaling pathway, PLC or mToR, triggered by Orx2 determines the functional outcome. Measuring PLC and mToR transcripts and proteins using laser microdissection of genetically marked cell-specific PrL-aBLA/Rspo2 pro-stress and IL/Drd1-pBLA/Ppp1r1b anti-stress microcircuits will allow phenotype, sexual, and circuit level disparity in activation. Another molecular change that will produce sexual distinctions in stress responsivity is Orx2 activity homologously increasing the number of available Orx2 receptors. Aim 2: Up-regulation of BLA Orx2 receptor expression reduces stress responsiveness in females compared with males. We posit that differences between females and males stem from molecular actions that increase Orx2 receptors strategically placed to inhibit pro-stress circuitry, especially in those individuals that exhibit enhanced fear conditioning. Changeable molecular cascades and up-regulation of Orx2 receptors are likely to produce stronger anti-stress microcircuitry activity and reduced stress reactivity.