Reelin, neuroendocrinology, and behaviour

在过去的20年里，我的研究计划的一般目的集中在理解细胞外基质蛋白Reelin的功能作用以及它们如何影响神经可塑性和行为：我们证明了Reelin主要在皮层和海马的GABA能神经元中表达，以及Reelin在末端树突领域的分泌如何调节树突棘上的突触强度。我们还展示了由慢性压力引起的特定大脑区域的Reelin缺陷如何带来特定的行为和神经化学变化。 在过去的授予周期（2015-2020），我的工作特别集中在中枢和外周Reelin在调节免疫和神经系统之间的串扰的影响。我们发现，Reelin缺陷不仅在大脑中，而且在免疫系统中引起特定的改变，这可能会使动物受到慢性应激的有害影响，并且一些抗炎药物在慢性应激时挽救Reelin表达水平。 最近，我们观察到，Reelin差异表达在特定的下丘脑核在大脑中的雄性和雌性大鼠（特别是在催产素表达细胞的室旁核，但也在视前核），海马Reelin是改变在女性怀孕期间，这些表达水平的差异改变在两种性别的慢性应激反应。这组新的数据使我们能够假设，下丘脑核中的Reelin表达可能会差异影响突触强度在特定的下丘脑电路中的男性和女性啮齿动物，直接参与调节的压力反应。 我们的研究计划将在不同层面上检验这一假设。首先，我们将对男性和女性下丘脑中的Reelin差异进行系统的评价，这将包括对表达Reelin的神经元亚型的适当鉴定和体视学计数。对于雌性动物，我们还将研究发情周期和妊娠期间的假定差异。第二，将在体外下丘脑突触体和培养的垂体细胞中研究Reelin在分子水平上对下丘脑突触可塑性和垂体的影响，通过使用包括添加外源性Reelin或通过使用特异性抗Reelin抗体阻断Reelin作用的范例，并分析Reelin信号转导蛋白激活、膜蛋白聚集、以及促进突触体中的蛋白质翻译。第三，我们将使用慢性应激的动物模型来评估其如何影响雄性和雌性大鼠下丘脑和垂体中的Reelin表达，以及其如何与特定的行为改变相关，并将测定下丘脑内Reelin输注或外周静脉注射Reelin是否影响慢性应激诱导的神经化学和行为改变。

The general purpose of my research program during the past 20 years has focussed on understanding the functional roles of the extracellular matrix protein Reelin and how they affect neural plasticity and behaviour: We demonstrated that Reelin was primarily expressed in GABAergic neurons in cortex and hippocampus, and how Reelin secretion in terminal dendritic fields regulated synaptic strength onto dendritic spines. We also showed how Reelin deficits in specific brain areas induced by chronic stress bring about specific behavioural and neurochemical alterations. During the past granting cycle (2015-2020) my work specifically focussed on the effects of central and peripheral Reelin in regulating the crosstalk between the immune and nervous systems. We showed that Reelin deficits bring about specific alterations not only in the brain but also in the immune system that may prime animals for the deleterious effects of chronic stress, and that some anti-inflammatory drugs rescue Reelin expression levels upon chronic stress. Recently, we observed that Reelin is differentially expressed in specific hypothalamic nuclei in the brain of male and female rats (particularly in oxytocin expressing cells in the paraventricular nucleus, but also in preoptic nuclei), that hippocampal Reelin is altered in females during pregnancy, and that these expression levels are differentially altered in the two sexes in response to chronic stress. This novel set of data allows us to hypothesize that Reelin expression in hypothalamic nuclei may differentially affect synaptic strength in specific hypothalamic circuits in male and female rodents that are directly involved in the regulation of the stress response. Our research program will examine this hypothesis at different levels. First, we will carry out a systematic evaluation of Reelin differences in male and female hypothalamus, this will include a proper identification and stereological counting of neuronal subtypes expressing Reelin. In the case of females, we will additionally study putative differences during the estrous cycle and pregnancy. Second, the effects of Reelin in hypothalamic synaptic plasticity and pituitary at the molecular level will be studied in hypothalamic synaptosomes in vitro and in cultured pituitary cells, by using a paradigm that involves adding exogenous Reelin or blocking Reelin actions by using specific anti-Reelin antibodies, and analyzing differences in the activation of Reelin signal transduction proteins, in membrane protein clustering, and in promoting protein translation in synaptosomes. Third, we will use an animal model of chronic stress to evaluate how it affects Reelin hypothalamic and pituitary expression in male and female rats, and how that relates to specific behavioural alterations, and will assay if intra-hypothalamic Reelin infusions or peripheral intravenous Reelin injections affect neurochemical and behavioural alterations induced by chronic stress.