Serotonergic, 5-HT2, Receptor-Mediated phosphoinositide Turnover and Mobilization of Calcium in Cultured Rat Retinal Pigment Epithelium Cells

NN Osborne, F FitzGibbon, M Nash, NP Liu, R Leslie, A Cholewinski

    Research output: Contribution to journalArticle

    28 Citations (Scopus)

    Abstract

    Cultured rat retinal pigment epithelium cells are shown to contain serotonergic, 5-HT2, receptors associated with phosphoinositide turnover and mobilization of intracellular calcium. Serotonin at a concentration of 10 μM induced a 2.5-fold increase in [3H]-inositol phosphates (more than 75% is in the form of [3H]-inositol-1-phosphate) accumulation within 30 min in cells preincubated in [3H]-myo-inositol and exposed to 5 mM lithium chloride. The EC50 value of serotonin was approx. 0.9 μM and the saturation concentration was 100 μM. Serotonin analogues like tryptamine, 5-methoxytryptamine, α-methyl-serotonin and the 5-HT2 agonists quipazine and DOI (1-[2,5-dimethoxy-4-iodophenyl]-2-aminopropane) all stimulated InsPs accumulation to some degree. Carbachol, noradrenaline, isoproterenol, dopamine, tryptophan, 5-hydroxytryptophan, 8-hydroxy-2 (di-n-propyl-amino) tetralin, 2-methyl-serotonin and NEC A (5′-[N-ethyl]-carboxamidoadenosine) were inactive. The serotonin-induced response was blocked most effectively by ketanserin and methysergide but not by 5-HT3 or 5-HT1, antagonists. The serotonin response was attenuated by the active phorbol ester, 4β-phorbol 12-myristate 13-acetate and this was attenuated by the non-selective protein kinase C inhibitor, staurosporine. Pertussis toxin failed to influence the serotonin-mediated phosphoinositide turnover. Addition of serotonin to cultures loaded with Fura-2 showed a transient increase in calcium concentrations in most of the cells. This change in calcium was independent of external calcium and the serotonin response was attenuated by ketanserin but not by the 5-HT3 antagonist granisetron. These studies provide clear evidence for the presence of 5-HT2 receptors, coupled to phosphoinositide metabolism and mobilization of calcium, on cultured rat retinal pigment epithelium cells.
    LanguageEnglish
    Pages2171-2179
    JournalVision research
    Volume33
    Issue number16
    DOIs
    Publication statusPublished - Nov 1993

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    Retinal Pigment Epithelium
    Serotonin
    Calcium
    Phosphatidylinositols
    Ketanserin
    Quipazine
    5-Methoxytryptamine
    Serotonin 5-HT2 Receptor Agonists
    phosphatidylinositol receptors
    Serotonin 5-HT1 Receptor Antagonists
    Granisetron
    Serotonin 5-HT3 Receptor Antagonists
    Lithium Chloride
    Methysergide
    5-Hydroxytryptophan
    Inositol Phosphates
    Staurosporine
    Protein C Inhibitor
    Fura-2
    Pertussis Toxin

    Keywords

    • 5-HT2 receptors
    • phosphoinositides
    • calcium
    • retinal pigmnt cells

    Cite this

    Osborne, NN ; FitzGibbon, F ; Nash, M ; Liu, NP ; Leslie, R ; Cholewinski, A. / Serotonergic, 5-HT2, Receptor-Mediated phosphoinositide Turnover and Mobilization of Calcium in Cultured Rat Retinal Pigment Epithelium Cells. 1993 ; Vol. 33, No. 16. pp. 2171-2179.
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    Serotonergic, 5-HT2, Receptor-Mediated phosphoinositide Turnover and Mobilization of Calcium in Cultured Rat Retinal Pigment Epithelium Cells. / Osborne, NN; FitzGibbon, F; Nash, M; Liu, NP; Leslie, R; Cholewinski, A.

    Vol. 33, No. 16, 11.1993, p. 2171-2179.

    Research output: Contribution to journalArticle

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