title: Regulation of action potential waveforms by axonal GABAA receptors in cortical pyramidal neurons.
abstract: GABAA receptors distributed in somatodendritic compartments play critical roles in regulating neuronal activities, including spike timing and firing pattern; however, the properties and functions of GABAA receptors at the axon are still poorly understood. By recording from the cut end (bleb) of the main axon trunk of layer -5 pyramidal neurons in prefrontal cortical slices, we found that currents evoked by GABA iontophoresis could be blocked by picrotoxin, indicating the expression of GABAA receptors in axons. Stationary noise analysis revealed that single-channel properties of axonal GABAA receptors were similar to those of somatic receptors. Perforated patch recording with gramicidin revealed that the reversal potential of the GABA response was more negative than the resting membrane potential at the axon trunk, suggesting that GABA may hyperpolarize the axonal membrane potential. Further experiments demonstrated that the activation of axonal GABAA receptors regulated the amplitude and duration of action potentials (APs) and decreased the AP-induced Ca2+ transients at the axon. Together, our results indicate that the waveform of axonal APs and the downstream Ca2+ signals are modulated by axonal GABAA receptors.
authors: Institute of Neuroscience, State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, P. R. China.
authors: Yang
authors: Y
authors: Xia
authors: Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan, P. R. China.
authors: Yuan
authors: Y
authors: Zhao
authors: Institute of Neuroscience, State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, P. R. China.
authors: Mingpo
authors: M
authors: Yang
authors: Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan, P. R. China.
authors: Shaoqun
authors: S
authors: Zeng
authors: State Key Laboratory of Cognitive Neuroscience and Learning & IDG/McGovern Institute for Brain Research, Center for Collaboration and Innovation in Brain and Learning Sciences, Beijing Normal University, Beijing, P. R. China.
authors: Yousheng
authors: Y
authors: Shu
mesh_terms: D000200:Action Potentials; D000818:Animals; D001369:Axons / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D020013:Calcium Signaling; D002540:Cerebral Cortex / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D058787:GABA-A Receptor Antagonists / Q000494:pharmacology; D006096:Gramicidin / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D010852:Picrotoxin / Q000494:pharmacology; D017966:Pyramidal Cells / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011963:Receptors, GABA-A / Q000235:genetics / Q000378:metabolism*
chemical_list: D058787:GABA-A Receptor Antagonists; D006096:Gramicidin; D007476:Ionophores; D010852:Picrotoxin; D011963:Receptors, GABA-A