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Recombinant human serotonin 5A receptors stably expressed in C6 glioma cells couple to multiple signal transduction pathways
Author(s) -
Noda Mami,
Yasuda Satsuki,
Okada Mitsuko,
Higashida Haruhiro,
Shimada Aki,
Iwata Nakao,
Ozaki Norio,
Nishikawa Kaori,
Shirasawa Sakiko,
Uchida Mayumi,
Aoki Shunsuke,
Wada Keiji
Publication year - 2003
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.2003.01518.x
Subject(s) - pertussis toxin , thapsigargin , receptor , intracellular , bapta , microbiology and biotechnology , signal transduction , biology , second messenger system , serotonin , inositol , forskolin , inositol trisphosphate receptor , ryanodine receptor , 5 ht receptor , chemistry , g protein , biochemistry
Human serotonin 5A (5‐HT 5A ) receptors were stably expressed in undifferentiated C6 glioma. In 5‐HT 5A receptors‐expressing cells, accumulation of cAMP by forskolin was inhibited by 5‐HT as reported previously. Pertussis toxin‐sensitive inhibition of ADP‐ribosyl cyclase was also observed, indicating a decrease of cyclic ADP ribose, a potential intracellular second messenger mediating ryanodine‐sensitive Ca 2+ mobilization. On the other hand, 5‐HT‐induced outward currents were observed using the patch‐clamp technique in whole‐cell configuration. The 5‐HT‐induced outward current was observed in 84% of the patched 5‐HT 5A receptor‐expressing cells and was concentration‐dependent. The 5‐HT‐induced current was inhibited when intracellular K + was replaced with Cs + but was not significantly inhibited by typical K + channel blockers. The 5‐HT‐induced current was significantly attenuated by 1,2‐bis(2‐aminophenoxy)ethane‐ N , N , N ′, N ′‐tetraacetic acid (BAPTA) in the patch pipette. Depleting intracellular Ca 2+ stores by application of caffeine or thapsigargin also blocked the 5‐HT‐induced current. Blocking G protein, the inositol triphosphate (IP3) receptor, or pretreatment with pertussis toxin, all inhibited the 5‐HT‐induced current. IP3 showed a transient increase after application of 5‐HT in 5‐HT 5A receptor‐expressing cells. It was concluded that in addition to the inhibition of cAMP accumulation and ADP‐ribosyl cyclase activity, 5‐HT 5A receptors regulate intracellular Ca 2+ mobilization which is probably a result of the IP3‐sensitive Ca 2+ store. These multiple signal transduction systems may induce complex changes in the serotonergic system in brain function.