Su Hailing, O'Dowd Diane K
Department of Anatomy and Neurobiology, University of California Irvine, Irvine, California 92697-1280, USA.
J Neurosci. 2003 Oct 8;23(27):9246-53. doi: 10.1523/JNEUROSCI.23-27-09246.2003.
The mushroom bodies, bilaterally symmetric regions in the insect brain, play a critical role in olfactory associative learning. Genetic studies in Drosophila suggest that plasticity underlying acquisition and storage of memory occurs at synapses on the dendrites of mushroom body Kenyon cells (Dubnau et al., 2001). Additional exploration of the mechanisms governing synaptic plasticity contributing to these aspects of olfactory associative learning requires identification of the receptors that mediate fast synaptic transmission in Kenyon cells. To this end, we developed a culture system that supports the formation of excitatory and inhibitory synaptic connections between neurons harvested from the central brain region of late-stage Drosophila pupae. Mushroom body Kenyon cells are identified as small-diameter, green fluorescent protein-positive (GFP+) neurons in cultures from OK107-GAL4;UAS-GFP pupae. In GFP+ Kenyon cells, fast EPSCs are mediated by alpha-bungarotoxin-sensitive nicotinic acetylcholine receptors (nAChRs). The miniature EPSCs have rapid rise and decay kinetics and a broad, positively skewed amplitude distribution. Fast IPSCs are mediated by picrotoxin-sensitive chloride conducting GABA receptors. The miniature IPSCs also have a rapid rate of rise and decay and a broad amplitude distribution. The vast majority of spontaneous synaptic currents in the cultured Kenyon cells are mediated byalpha-bungarotoxin-sensitive nAChRs or picrotoxin-sensitive GABA receptors. Therefore, these receptors are also likely to mediate synaptic transmission in Kenyon cells in vivo and to contribute to plasticity during olfactory associative learning.
蕈形体是昆虫大脑中双侧对称的区域，在嗅觉联想学习中起关键作用。对果蝇的遗传学研究表明，记忆获取和存储所依赖的可塑性发生在蕈形体肯扬细胞树突上的突触处（Dubnau等人，2001年）。要进一步探究有助于嗅觉联想学习这些方面的突触可塑性调控机制，需要鉴定介导肯扬细胞快速突触传递的受体。为此，我们开发了一种培养系统，该系统支持从晚期果蝇蛹的中枢脑区采集的神经元之间形成兴奋性和抑制性突触连接。在来自OK107-GAL4;UAS-GFP蛹的培养物中，蕈形体肯扬细胞被鉴定为小直径、绿色荧光蛋白阳性（GFP+）的神经元。在GFP+肯扬细胞中，快速兴奋性突触后电流（EPSCs）由α-银环蛇毒素敏感的烟碱型乙酰胆碱受体（nAChRs）介导。微小兴奋性突触后电流具有快速的上升和衰减动力学以及广泛的、正偏态的幅度分布。快速抑制性突触后电流（IPSCs）由印防己毒素敏感的氯离子传导GABA受体介导。微小抑制性突触后电流也具有快速的上升和衰减速率以及广泛的幅度分布。培养的肯扬细胞中绝大多数自发突触电流由α-银环蛇毒素敏感的nAChRs或印防己毒素敏感的GABA受体介导。因此，这些受体也可能在体内介导肯扬细胞的突触传递，并在嗅觉联想学习过程中促进可塑性。
