title: Differential contribution of TRPM4 and TRPM5 nonselective cation channels to the slow afterdepolarization in mouse prefrontal cortex neurons.
abstract: In certain neurons from different brain regions, a brief burst of action potentials can activate a slow afterdepolarization (sADP) in the presence of muscarinic acetylcholine receptor agonists. The sADP, if suprathreshold, can contribute to persistent non-accommodating firing in some of these neurons. Previous studies have characterized a Ca(2+)-activated non-selective cation (CAN) current (ICAN ) that is thought to underlie the sADP. ICAN depends on muscarinic receptor stimulation and exhibits a dependence on neuronal activity, membrane depolarization and Ca(2+)-influx similar to that observed for the sADP. Despite the widespread occurrence of sADPs in neurons throughout the brain, the molecular identity of the ion channels underlying these events, as well as ICAN , remains uncertain. Here we used a combination of genetic, pharmacological and electrophysiological approaches to characterize the molecular mechanisms underlying the muscarinic receptor-dependent sADP in layer 5 pyramidal neurons of mouse prefrontal cortex. First, we confirmed that in the presence of the cholinergic agonist carbachol a brief burst of action potentials triggers a prominent sADP in these neurons. Second, we confirmed that this sADP requires activation of a PLC signaling cascade and intracellular calcium signaling. Third, we obtained direct evidence that the transient receptor potential (TRP) melastatin 5 channel (TRPM5), which is thought to function as a CAN channel in non-neural cells, contributes importantly to the sADP in the layer 5 neurons. In contrast, the closely related TRPM4 channel may play only a minor role in the sADP.
authors.affiliation: Department of Neuroscience, Columbia University Medical Center, New York State Psychiatric Institute New York, NY, USA.
authors.forename: Ya-Ting
authors.initials: YT
authors.lastname: Lei
authors.affiliation: Department of Neuroscience, Columbia University Medical Center, New York State Psychiatric Institute New York, NY, USA.
authors.forename: Sebastien J
authors.initials: SJ
authors.lastname: Thuault
authors.affiliation: Equipe Avenir, Institut National de la Santé et de la Recherche Médicale, Service de Néphrologie, Hôpital Bichat, Université Paris Paris, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Launay
authors.affiliation: Monell Chemical Senses Center Philadelphia, PA, USA.
authors.forename: Robert F
authors.initials: RF
authors.lastname: Margolskee
authors.affiliation: Department of Neuroscience, Columbia University Medical Center, New York State Psychiatric Institute New York, NY, USA ; Howard Hughes Medical Institute, Columbia University New York, NY, USA ; Kavli Institute for Brain Sciences, Columbia University New York, NY, USA ; Department of Psychiatry, Columbia University New York, NY, USA.
authors.forename: Eric R
authors.initials: ER
authors.lastname: Kandel
authors.affiliation: Department of Neuroscience, Columbia University Medical Center, New York State Psychiatric Institute New York, NY, USA ; Howard Hughes Medical Institute, Columbia University New York, NY, USA ; Kavli Institute for Brain Sciences, Columbia University New York, NY, USA ; Department of Pharmacology, Columbia University New York, NY, USA.
authors.forename: Steven A
authors.initials: SA
authors.lastname: Siegelbaum
keywords: Ca2+-activated non-selective cation (CAN) current; muscarinic receptors; persistent firing; slow afterdepolarization (sADP); transient receptor potential melastatin 5 channel (TRPM5)