Excitability of pontine startle processing neurones is regulated by the two-pore-domain K+ channel TASK-3 coupled to 5-HT2C receptors.
Eur J Neurosci
; 28(5): 931-40, 2008 Sep.
Article
em En
| MEDLINE
| ID: mdl-18691333
ABSTRACT
The mammalian startle reflex is a fast response to sudden intense sensory stimuli that can be increased by anxiety or decreased by reward. The cellular integration of sensory and modulatory information takes place in giant neurones of the caudal pontine reticular formation (PnC). The startle reflex is known to be enhanced by 5-hydroxytryptamine (5-HT); however, signalling mechanisms that change the excitability of the PnC giant neurones are poorly understood. Possible molecular candidates are two-pore-domain K(+) (K(2)P) channels that generate a variable K(+) background conductance and control neuronal excitability upon activation of G-protein-coupled receptors. We demonstrate by in situ hybridization that the K(2)P channel TASK-3 is substantially expressed in PnC giant neurones. Brain slice recordings revealed a corresponding background K(+) current in these cells that forms about 30% of the outward current at -30 mV. Inactivation of TASK-3 at pH 6.4 and by ruthenium red depolarized the cells by about 7 mV and increased the action potential frequency as well as duration. Specific activation of Galpha(q)-coupled 5-HT(2) receptors with alpha-methyl 5-HT evoked a similar increase of neuronal excitability. Consistently, we measured afferent synaptic inputs from serotonergic raphe neurones and detected 5-HT(2C) receptors in PnC giant neurones by immunohistochemistry. Thus, neuronal excitability of PnC giant neurones in vivo is most likely increased by serotonergic projections via the K(2)P channel TASK-3.
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Base de dados:
MEDLINE
Assunto principal:
Formação Reticular
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Ponte
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Transmissão Sináptica
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Canais de Potássio de Domínios Poros em Tandem
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Receptor 5-HT2C de Serotonina
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Neurônios
Idioma:
En
Ano de publicação:
2008
Tipo de documento:
Article
País de afiliação:
Alemanha