CNRS, UMR8256 "Biological Adaptation and Ageing", Institut de Biologie Paris-Seine (IBPS) , F-75005 Paris, France ; Université Pierre et Marie Curie (UPMC, Paris 6), Sorbonne Universités , Paris, F-75005, France.
CNRS, UMR-5203, Institut de Génomique Fonctionnelle , Montpellier, F-34094, France ; Institut National de la Santé et de la Recherche Médicale, U661 , Montpellier, F-34094, France ; Universités de Montpellier 1 & 2, UMR-5203 , Montpellier, F-34094, France.
eNeuro. 2015 Aug 31;2(4). doi: 10.1523/ENEURO.0060-15.2015. eCollection 2015 Jul-Aug.
Type 10A phosphodiesterase (PDE10A) is highly expressed in the striatum, in striatonigral and striatopallidal medium-sized spiny neurons (MSNs), which express D1 and D2 dopamine receptors, respectively. PDE10A inhibitors have pharmacological and behavioral effects suggesting an antipsychotic profile, but the cellular bases of these effects are unclear. We analyzed the effects of PDE10A inhibition in vivo by immunohistochemistry, and imaged cAMP, cAMP-dependent protein kinase A (PKA), and cGMP signals with biosensors in mouse brain slices. PDE10A inhibition in mouse striatal slices produced a steady-state increase in intracellular cAMP concentration in D1 and D2 MSNs, demonstrating that PDE10A regulates basal cAMP levels. Surprisingly, the PKA-dependent AKAR3 phosphorylation signal was strong in D2 MSNs, whereas D1 MSNs remained unresponsive. This effect was also observed in adult mice in vivo since PDE10A inhibition increased phospho-histone H3 immunoreactivity selectively in D2 MSNs in the dorsomedial striatum. The PKA-dependent effects in D2 MSNs were prevented in brain slices and in vivo by mutation of the PKA-regulated phosphorylation site of 32 kDa dopamine- and cAMP-regulated phosphoprotein (DARPP-32), which is required for protein phosphatase-1 inhibition. These data highlight differences in the integration of the cAMP signal in D1 and D2 MSNs, resulting from stronger inhibition of protein phosphatase-1 by DARPP-32 in D2 MSNs than in D1 MSNs. This study shows that PDE10A inhibitors share with antipsychotic medications the property of activating preferentially PKA-dependent signaling in D2 MSNs.
10A 型磷酸二酯酶（PDE10A）在纹状体中高度表达，在纹状体苍白球中间神经元（MSNs）和纹状体黑质 MSNs 中表达分别表达 D1 和 D2 多巴胺受体。PDE10A 抑制剂具有药理学和行为学作用，提示具有抗精神病作用谱，但这些作用的细胞基础尚不清楚。我们通过免疫组织化学分析了体内 PDE10A 抑制的作用，并使用生物传感器在小鼠脑切片中成像 cAMP、cAMP 依赖性蛋白激酶 A（PKA）和 cGMP 信号。PDE10A 抑制在小鼠纹状体内切片中产生 D1 和 D2 MSNs 中细胞内 cAMP 浓度的稳态增加，表明 PDE10A 调节基础 cAMP 水平。令人惊讶的是，D2 MSNs 中 PKA 依赖性 AKAR3 磷酸化信号很强，而 D1 MSNs 仍然没有反应。这种效应也在体内成年小鼠中观察到，因为 PDE10A 抑制选择性地增加了背侧纹状体中 D2 MSNs 中的磷酸组蛋白 H3 免疫反应性。在脑切片中和体内，通过突变 32 kDa 多巴胺和 cAMP 调节磷酸蛋白（DARPP-32）的 PKA 调节磷酸化位点，可防止 PKA 依赖性效应在 D2 MSNs 中，该位点对于蛋白磷酸酶-1 抑制是必需的。这些数据突出了 D1 和 D2 MSNs 中 cAMP 信号整合的差异，这是由于 D2 MSNs 中 DARPP-32 对蛋白磷酸酶-1 的抑制作用强于 D1 MSNs。这项研究表明，PDE10A 抑制剂与抗精神病药物具有共同的特性，即优先激活 D2 MSNs 中 PKA 依赖性信号。
