Serotonin-sensitive leakage channel in Drosophila central neurons

This article reports the analysis of a novel serotonin (5-HT)-sensitive leak channel. The 5-HT responses were recorded in acutely dissociated Drosophila adult and larval central nervous system (CNS) neurons by the patch-clamp method, in an attempt to establish a model preparation suitable for the genetic study of signal transduction underlying central neurotransmission. Focal perfusion or iontophoresis of 5-HT onto some patched neurons induced either an apparent inward or outward current. This apparent outward current is able to cause a strong hyperpolarization of the neuron. This article focuses on the predominant hyperpolarizing response, which is observed in a significant fraction of larger CNS neurons and in different developmental stages. The hyperpolarizing response is in fact mediated by inhibiting an inward leak current, which has a reversal potential around 0 mV. This 5-HT-sensitive leak current appears to be mediated mainly by one type of newly identified leak channel with a similar reversal potential of 0 mV and a conductance of 24 pS. In addition, it was also demonstrated that neurotransmitter-induced responses in both larval and adult Drosophila CNS neurons can be analyzed in this acutely dissociated preparation.