期刊
PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY
卷 463, 期 1, 页码 89-102出版社
SPRINGER HEIDELBERG
DOI: 10.1007/s00424-011-1056-9
关键词
Thalamic function; Sleep/wake activity; K-2P channels; Muscarinic receptor; Phospholipid signaling
类别
资金
- DFG [FOR 1086/2, TP2, TP1]
- IZKF Munster [BU3/010/10]
Modulation of the standing outward current (I (SO)) by muscarinic acetylcholine (ACh) receptor (MAChR) stimulation is fundamental for the state-dependent change in activity mode of thalamocortical relay (TC) neurons. Here, we probe the contribution of MAChR subtypes, G proteins, phospholipase C (PLC), and two pore domain K+ (K-2P) channels to this signaling cascade. By the use of spadin and A293 as specific blockers, we identify TWIK-related K+ (TREK)-1 channel as new targets and confirm TWIK-related acid-sensitve K+ (TASK)-1 channels as known effectors of muscarinic signaling in TC neurons. These findings were confirmed using a high affinity blocker of TASK-3 and TREK-1, namely, tetrahexylammonium chloride. It was found that the effect of muscarinic stimulation was inhibited by M(1)AChR-(pirenzepine, MT-7) and M(3)AChR-specific (4-DAMP) antagonists, phosphoinositide-specific PLC beta (PI-PLC) inhibitors (U73122, ET-18-OCH3), but not the phosphatidylcholine-specific PLC (PC-PLC) blocker D609. By comparison, depleting guanosine-5'-triphosphate (GTP) in the intracellular milieu nearly completely abolished the effect of MAChR stimulation. The block of TASK and TREK channels was accompanied by a reduction of the muscarinic effect on I (SO). Current-clamp recordings revealed a membrane depolarization following MAChR stimulation, which was sufficient to switch TC neurons from burst to tonic firing under control conditions but not during block of M(1)AChR/M(3)AChR and in the absence of intracellular GTP. These findings point to a critical role of G proteins and PLC as well as TASK and TREK channels in the muscarinic modulation of thalamic activity modes.
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