Graham Devon L, Buendia Matthew A, Chapman Michelle A, Durai Heather H, Stanwood Gregg D
Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, Florida, 32303.
Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee, 37232.
Synapse. 2015 Sep;69(9):434-45. doi: 10.1002/syn.21830. Epub 2015 Jun 3.
G(αq) -coupled receptors are ubiquitously expressed throughout the brain and body, and it has been shown that these receptors and associated signaling cascades are involved in a number of functional outputs, including motor function and learning and memory. Genetic alterations to G(αq) have been implicated in neurodevelopmental disorders such as Sturge-Weber syndrome. Some of these associated disease outcomes have been modeled in laboratory animals, but as G(αq) is expressed in all cell types, it is difficult to differentiate the underlying circuitry or causative neuronal population. To begin to address neuronal cell type diversity in G(αq) function, we utilized a conditional knockout mouse whereby G(αq) was eliminated from telencephalic glutamatergic neurons. Unlike the global G(αq) knockout mouse, we found that these conditional knockout mice were not physically different from control mice, nor did they exhibit any gross motor abnormalities. However, similarly to the constitutive knockout animal, G(αq) conditional knockout mice demonstrated apparent deficits in spatial working memory. Loss of G(αq) from glutamatergic neurons also produced enhanced sensitivity to cocaine-induced locomotion, suggesting that cortical G(αq) signaling may limit behavioral responses to psychostimulants. Screening for a variety of markers of forebrain neuronal architecture revealed no obvious differences in the conditional knockouts, suggesting that the loss of G(αq) in telencephalic excitatory neurons does not result in major alterations in brain structure or neuronal differentiation. Taken together, our results define specific modulation of spatial working memory and psychostimulant responses through disruptions in G(αq) signaling within cerebral cortical glutamatergic neurons.
G(αq)偶联受体在大脑和身体中广泛表达,并且已经表明这些受体及相关信号级联参与了许多功能输出,包括运动功能以及学习和记忆。G(αq)的基因改变与诸如斯特奇-韦伯综合征等神经发育障碍有关。其中一些相关的疾病结果已在实验动物中建模,但由于G(αq)在所有细胞类型中均有表达,因此难以区分潜在的神经回路或致病神经元群体。为了开始研究G(αq)功能中的神经元细胞类型多样性,我们利用了一种条件性敲除小鼠,通过该小鼠从端脑谷氨酸能神经元中消除了G(αq)。与全身性G(αq)敲除小鼠不同,我们发现这些条件性敲除小鼠在身体上与对照小鼠没有差异,也没有表现出任何明显的运动异常。然而,与组成型敲除动物类似,G(αq)条件性敲除小鼠在空间工作记忆方面表现出明显缺陷。谷氨酸能神经元中G(αq)的缺失还导致对可卡因诱导的运动的敏感性增强,这表明皮质G(αq)信号传导可能会限制对精神兴奋剂的行为反应。对多种前脑神经元结构标记物的筛选显示,条件性敲除小鼠没有明显差异,这表明端脑兴奋性神经元中G(αq)的缺失不会导致大脑结构或神经元分化的重大改变。综上所述,我们的结果通过破坏大脑皮质谷氨酸能神经元内的G(αq)信号传导,定义了对空间工作记忆和精神兴奋剂反应的特定调节。