Human Post-Mortem Pathology (in-situ Hyb etc.)

重度抑郁障碍(MDD)的特征是神经元和神经胶质细胞的密度和大小减少。 前额叶皮质中的细胞。我们发现这些细胞变化是年龄相关的，正如杨格抑郁所显示的那样 胶质细胞(星形胶质细胞)密度显著降低，而老年抑郁症患者明显 锥体(可能是谷氨酸)神经元和钙结合蛋白免疫反应的密度降低 中间神经元(主要是共定位的GABA)。因为，星形胶质细胞调节谷氨酸的浓度， 其中是神经毒性的，我们认为MDD早期星形胶质细胞的缺陷可能导致 谷氨酸在细胞外的浓度，以及锥体神经元和GABA神经元在生命后期的减少。 因此，可能存在与神经成像相一致的GABA/谷氨酸稳态失衡。 研究显示MDD患者GABA和谷氨酸水平的变化在抗抑郁药治疗中是可逆的 (SSRI)治疗。皮质神经元通过(至少)5-羟色胺作用于5-羟色胺，以复杂的方式进行调节。 1A和-2A受体定位于这些神经元和星形胶质细胞上。5-羟色胺能神经递增的病理学 轴突和突触后受体可能与谷氨酸和/或GABA的活性、数量和大小有关 MDD中的神经元和星形胶质细胞。到目前为止，还没有关于表达或定位的研究 抑郁症患者特定皮质细胞类型上的5-羟色胺受体。 总体假设是，抑郁症患者的脑白质密度会随着年龄的增长而降低。 星形胶质细胞、谷氨酸锥体神经元和GABA中间神经元的表达 这些细胞上的5-羟色胺-1A和-2A受体将发生改变。这些像元减少也将相互关联 与年龄相关的前额叶5-羟色胺神经支配缺失。为了检验这些假设，我们将 直接鉴定和定量星形胶质细胞和谷氨酸、GABA神经元的堆积密度 特定蛋白质的信使核糖核酸(目标1)。此外，我们将评估5-羟色胺系统调节器的完整性。 (突触后受体和突触前轴突) 5-羟色胺-1 A和-2 A受体的mRNA表达(目标2)和5-羟色胺轴突密度 表达5-羟色胺转运体(目标3)。双重原位杂交、免疫组织化学和三维 细胞计数技术将用于相同的死后组织，从前额叶皮质采样 在我们的细胞计数研究中，使用MDD和非抑郁对照的年轻和老年受试者。 该项目将确定谷氨酸、GABA和5-羟色胺相互作用的细胞底物。 皮质及其在抑郁症病因学、病理生理学和年龄相关进展中的潜在作用。它 还可能揭示预防抑郁症和更好的抗抑郁药物治疗的新靶点。

Major depressive disorder (MDD) is characterized by reductions in the density and size of neuronal and glial cells in prefrontal cortex. We find these cellular changes to be age-dependent as younger depressed show prominent reductions in the density of glial cells (astrocytes), whereas older depressed have marked reductions in the density of pyramidal (presumably glutamate) neurons and calbindin-immunoreactive interneurons (mostly co-localizing GABA). Since, astrocytes regulate concentration of glutamate, an excess of which is neurotoxic, we propose that an early deficit in astrocytes in MDD could lead to an increase in the extracellular concentration of glutamate and to a reduction in pyramidal and GABA neurons later in life. Hence, there may be imbalances in GABA/glutamate homeostasis that are consistent with neuroimaging studies revealing changes in levels of GABA and glutamate in MDD which are reversible with antidepressant (SSRI) treatment. Cortical neurons are regulated in complex ways by serotonin acting (at least) at serotonin- 1A and -2A receptors located on these neurons and astrocytes. Pathology in ascending serotoninergic axons and postsynaptic receptors may be related to the activity, number and size of glutamate and/or GABA neurons and astrocytes in MDD. To date, there have been no studies on the expression or localization of serotonin receptors on specific cortical cell types in depression. The overall hypothesis is that in depression there will be age-dependent reductions in the density of astrocytes, glutamate pyramidal neurons and GABA interneurons, and that the expression of regulatory serotonin-1A and -2A receptors on these cells will be altered. These cell reductions will also be correlated with an age-related loss of serotonin innervation in prefrontal layers. To test these hypotheses, we will directly identify and quantify the packing density of astrocytes and glutamate and GABA neurons expressing mRNA for specific proteins (Aim 1). Moreover, we will assess the integrity of the serotonin system regulators (postsynaptic receptors and presynaptic axons) of prefrontal cells by estimating the proportion of cell types expressing mRNA for serotonin-1 A and -2A receptors (Aim 2), and the density of serotonin axons expressing the serotonin transporter (Aim 3). Double in situ hybridization, immunohistochemistry and 3-D cell counting techniques will be used in the same postmortem tissue sampled from the prefrontal cortex of younger and older subjects with MDD and non-depressed controls as used in our cell counting studies. This project will identify the cellular substrates of glutamate, GABA and serotonin interactions in the cortex and their potential role in the etiology, pathophysiology and age-related progression of depression. It may also reveal novel targets for preventing depressive illness and better antidepressant drug treatment.