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XB-ART-25988
Pflugers Arch 1990 Apr 01;4161-2:7-16.
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Short- and long-term desensitization of serotonergic response in Xenopus oocytes injected with brain RNA: roles for inositol 1,4,5-trisphosphate and protein kinase C.

Singer D , Boton R , Moran O , Dascal N .


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In Xenopus oocytes injected with rat brain RNA, serotonin (5HT) and acetylcholine (ACh) evoke membrane responses through a common biochemical cascade that includes activation of phospholipase C, production of inositol 1,4,5-trisphosphate (Ins1,4,5-P3), release of Ca2+ from intracellular stores, and opening of Ca-dependent Cl- channels. The response is a Cl- current composed of a transient component (5HT1 or ACh1) and a slow, long-lasting component (5HT2 or ACh2). Here we show that only the fast, but not the slow, component of the response is subject to desensitization that follows a previous application of the transmitter. The recovery of 5HT1 from desensitization is biphasic, suggesting the existence of two types of desensitization: short-term desensitization (STD), which lasts for less than 0.5 h; and long-term desensitization (LTD) lasting for up to 4 h. The desensitization between 5HT and ACh is heterologous and long-lasting. We searched for (a) the molecular target and (b) the cause of desensitization. (a) Pre-exposure to 5HT does not reduce the response evoked by intracellular injection of Ca2+ and by Ca2+ influx. Cl- current evoked by intracellular injection of Ins1,4,5-P3 was reduced shortly after application of 5HT, but fully recovered 30 min later. Thus, the Cl- channel is not a target for desensitization. Neither Ins1,4,5-P3 receptor nor the Ca2+ store is a target of LTD but they may be the targets of STD. (b) Ca2+ injection did not inhibit the 5HT response, suggesting that Ca2+ is not a sole cause of STD or LTD.(ABSTRACT TRUNCATED AT 250 WORDS)

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Species referenced: Xenopus
Genes referenced: acot7 ins sult2a1

References [+] :
Alkon, A spatial-temporal model of cell activation. 1988, Pubmed