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This Article Full Text Full Text (PDF) All Versions of this Article: 571/1/43    most recent jphysiol.2005.101675v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Mejia-Gervacio, S. Articles by Marty, A. Search for Related Content PubMed PubMed Citation Articles by Mejia-Gervacio, S. Articles by Marty, A. Related Collections Cellular

¹ Laboratoire de Physiologie Cérébrale, CNRS UMR 8118, 45 rue des Saints Pères, 75006 Paris, France

Recent work has shown that certain neurones have axonal GABA_A receptors, whose tonic activation modifies their firing properties and neurotransmitter release capability. In addition, results obtained in interneurones of the molecular layer of the cerebellum indicate that action potential-released GABA binds back to the axon that released it, generating an autoreceptor current. In the present paper, we show that at physiological Cl^–_i concentration (15 mM) and at 34–36°C, the autoreceptor current generates a large amplitude (up to 21 mV) afterdepolarization that lasts for about 150 ms, and that occasionally leads to double firing. Furthermore we show that elimination of the afterdepolarization, by either blocking GABA_A receptors, or eliminating the autoreceptor currents through prolonged whole-cell recording, decreases burst firing. I_h (a hyperpolarization-activated current) was previously found to be prominent in interneurone axons. We show that blocking I_h leads to an increase in the amplitude of the autoreceptor current as well as of the associated afterdepolarization, suggesting a shunting effect of I_h on autoreceptor-mediated afterdepolarization. Conversely, blocking I_h accentuates burst firing. The effects of autoreceptor-mediated afterdepolarization on firing are prominent during a period of development when interneurone synapses are stabilized and vanish by postnatal day 17 (PN 17), together with the expression of the autoreceptor current. Altogether, this work reveals a new role for autoreceptors in the regulation of cell excitability and firing pattern, which may contribute to the development and stabilization of the cerebellar network.

(Received 10 November 2005; accepted after revision 7 December 2005; first published online 8 December 2005)
Corresponding author A. Marty: Laboratoire de Physiologie Cérébrale, CNRS UMR 8118, 45 rue des Saints Pères, 75006 Paris, France. Email: alain.marty{at}Univ-paris5.fr

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