Autoradiographic localization of muscimol and baclofen binding sites in rodent cingulate cortex.
Autoradiographic localization of muscimol and baclofen binding sites in rodent cingulate cortex.
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啮齿动物扣带皮层中蝇蕈醇和巴氯芬结合位点的放射自显影定位。
DOI：
10.1007/bf00247536
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发表时间：
1988
影响因子：
2
通讯作者：
Hedberg,TG
中科院分区：
文献类型：
--
作者：
Vogt,BA;Hedberg,TG
本文用放射自显影技术分析了大鼠扣带回29c区和24b区~3H-蝇草酚和~H-巴氯芬结合的层状分布。在29c区有一个单峰，Ia层的单峰为320±26粒/2500μm2。深层结合量为Ia层的46%~71%。与11：00-14：00相比，在22：00-01：00灌流的脑Ia层的结合增加了320%。除Ia层外，24b区的蝇草酚结合量在各层间均较均匀，且高于29c区。巴氯芬结合在两个区域都是均匀的，但在24b区比在29c区大120%，并且没有日变化。为了在细胞水平上定位蝇醇结合部位，在29c区进行了两种类型的损伤实验。首先，用神经毒素鹅膏菌酸消融大脑皮质固有的神经元，降低了蝇毒酚的结合，使Ia层减少了70%，深层减少了29%-42%。第二，刀切是为了将扣带回皮质与外源性纤维通路隔离开来，增加了除Ia层以外的所有层中蝇草醇的结合。相反，将表层和深层分离出来的刀伤在所有层中都产生了明显的苍蝇酚结合下降。综上所述，蝇毒蛾结合部位在29c区分布不均，夜间Ia层为结合高峰。由于实验观察表明，苍蝇酚结合位于锥体细胞顶束树突上，可能是兴奋性丘脑和内源性抑制性传入通过顶树突上的GABA受体在到达胞体之前相互作用的。
The laminar distribution of3H-muscimol and3H-baclofen binding was analyzed autoradiographically in areas 29c and 24b of rat cingulate cortex. Muscimol binding was heterogeneous in area 29c with a single peak in layer Ia of 320±26 grains per 2500 μm2. Binding in deeper layers was between 46% and 71% of that in layer Ia. There was a marked diurnal variation in muscimol binding in area 29c such that binding was elevated by 320% in layer Ia of brains perfused at 22∶00–01∶00 versus those perfused at 11∶00–14∶00. Muscimol binding in area 24b was uniform across all layers and was higher than that in area 29c except for in layer Ia. Baclofen binding was homogeneous in both areas, but was 120% greater in area 24b than in area 29c, and showed no diurnal variations. To localize muscimol binding sites at the cellular level, two types of lesion experiments were conducted in area 29c. First, ablation of neurons intrinsic to this cortex with the neurotoxin ibotenic acid reduced muscimol binding to homogeneity with a 70% reduction in layer Ia and a 29–42% reduction in deeper layers. Second, knife cuts, which were placed to isolate cingulate cortex from fiber pathways originating extrinsically, increased muscimol binding in all layers except layer Ia. Conversely, knife cuts which isolated superficial from deep layers yielded a marked drop in muscimol binding in all layers. In conclusion, muscimol binding sites are heterogeneously distributed in area 29c with peak binding in layer Ia at night. Since experimental observations suggest that muscimol binding is located on pyramidal cell apical tuft dendrites, it is possible that excitatory thalamic and intrinsic inhibitory input via GABAAreceptors on apical dendrites interact before arriving at the soma.