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Published online: 19 November 2008 | doi:10.1038/nchina.2008.273

Synaptic development: Making long-term changes

Felix Cheung

Introduction

© (2008) istockphoto.com/Sebastian Kaulitzki

The brain holds billions of neurons that are connected to each other through synapses. These synapses undergo structural modification in response to new stimuli and learning experiences. For example, high-frequency stimulation causes GABAergic synapses, which communicate by using the neurotransmitter GABA (-aminobutyric acid) to grow stronger, thereby strengthening memory; low-frequency stimulation causes GABAergic synapses to weaken, thereby clearing out old memory traces. Xiaohui Zhang at the Chinese Academy of Sciences in Shanghai, Muming Poo at University of California Berkeley and co-workers¹ have found that postsynaptic GABA_B receptors — a type of GABA receptor — play a regulatory role in the long-term modification of GABAergic synapses.

The researchers studied GABAergic synapses in hippocampal slices of rats during postnatal development — the only stage when synapses can be stimulated by GABA. They found that GABAergic synapses underwent long-term modification when subjected to repetitive stimulation.

High-frequency stimulation (20–50 Hz) led to strengthening (potentiation) of GABAergic synapses, whereas low-frequency stimulation (5 Hz) led to weakening (depression). The potentiation would not occur when GABA_B receptors were blocked, whereas the depression was independent of GABA_B receptor activation. In fact, low-frequency stimulation led to potentiation, instead of depression, when the activity of GABA_B receptors was raised.

The researchers further revealed that there are three prerequisites for long-term potentiation: postsynaptic simulation, and the activation of GABA_A and GABA_B receptors. Together, the findings show that postsynaptic GABA_B receptors mediate the long-term potentiation of developing GABAergic synapses.

The authors of this work are from:
Institute of Neuroscience, State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China; Division of Neurobiology, Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, California, USA.

Reference

1. Xu, C., Zhao, M. X., Poo, M. M. & Zhang, X. H. GABAB receptor activation mediates frequency-dependent plasticity of developing GABAergic synapses. Nature Neurosci. doi:10.1038/nn.2215 (2008). | Article |