Behavioral and physiological roles of the striatal GABAergic interneuronal types

纹状体是基底神经节神经回路的中心结构，其介导多种脑功能，包括运动控制、运动学习和奖励相关行为。它包含一些GABA能中间神经元类型，它们在形态和电生理特性上不同。然而，它们的行为和生理作用的差异仍然未知。本实验研究了含有生长抑素（SST）和小清蛋白（PVA）的两种GABA能中间神经元类型在脑缺血中的作用。我们利用免疫毒素细胞靶向消除特定的神经元类型的神经回路，并研究了由此产生的表型变化。为了消除含有SST的纹状体GABA能中间神经元，我们将人白细胞介素-2受体α亚基（IL-2 R α）基因盒导入小鼠前生长抑素原基因位点，产生突变小鼠。这些小鼠纹状体内注射重组免疫毒素，突变体中靶神经元的数量减少。突变体的表型分析表明，含SST的GABA能中间神经元在抑制自发运动行为中起重要作用。此外，为了消除含有PVA的纹状体GABA能中间神经元，我们尝试将人IL-2 R α盒导入小鼠PVA基因位点，产生突变小鼠。将基因敲入的靶向载体导入胚胎干细胞，通过PCR和Southern印迹杂交筛选携带靶向突变的细胞。我们成功地获得了多个携带靶向突变的ES细胞。使用这些细胞，我们正计划产生敲入突变小鼠，并进行免疫毒素细胞靶向，以阐明纹状体GABA能中间神经元含有PVA的行为和生理作用。

The striatum is a central structure of the basal ganglia neural circuitry that mediates a variety of brain functions including motor control, motor learning, and reward-associated behavior. It contains some GABAergic interneuronal types that are different in their morphology and electrophysiological property. However, the difference in their behavioral and physiological roles remains unknown. In the present study, we addressed to study the roles of two kinds of straital GABAergic interneuronal types containing somatostatin (SST) or parvalbumin (PVA). We utilized immunotoxin cell targeting to eliminate the specific neuronal type from the neural circuitry and studied the resultant phenotypic changes. To eliminate the striatal GABAergic interneurons containing SST, we generated the mutant mice in which the human interleukin-2 receptor a-subunit (IL-2Rα) gene cassette was introduced into the mouse preprosomatostatin gene locus. These mice were injected intrastriatally with the recombinant immunotoxin, and the number of target neurons were reduced in the mutants. Phenotypic analysis of the mutants indicated that the SST-containing GABAergic interneurons play an important role in suppression of spontaneous motor behavior. In addition, to eliminate the straital GABAergic interneurons containing PVA we tried to produce the mutant mice in which the human IL-2Rα cassette was introduced into the mouse PVA gene locus. The knock-in targeting vector was introduced into embryonic stem (ES) cells, and the cells carrying the targeted mutation were screened with PCR and southern blot hybridization. We succeeded in obtaining multiple ES cells carrying the targeted mutation. Using these cells we are planning to generate the knock-in mutant mice and perform immunotoxin cell targeting to elucidate the behavioral and physiological roles of the striatal GABAergic interneurons containing PVA.