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Phloretin as an Antagonist of Prostaglandin F 2α Receptor in Cultured Rat Astrocytes
Author(s) -
Kitanaka Junichi,
Ishibashi Tadashi,
Baba Akemichi
Publication year - 1993
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 - 10.1111/j.1471-4159.1993.tb03204.x
Subject(s) - phloretin , chemistry , stimulation , prostaglandin , intracellular , antagonist , biochemistry , endocrinology , medicine , receptor , biology
The effect of phloretin on prostaglandin (PG) F 2α ‐induced phosphoinositide hydrolysis and elevation of intracellular Ca 2+ concentration was examined in cultured rat astrocytes. Phloretin inhibited PGF 2α (1 μ M )‐induced phosphoinositide hydrolysis in a concentration‐dependent manner with an IC 50 value of 16 μ M . The inhibitory action of phloretin was specific for PGs. The addition of increasing concentrations of phloretin caused progressive shifts of the dose‐response curves of PGF 2α to the right. In digitoninpermeabilized astrocytes, phloretin (100 μ M ) inhibited the stimulation induced by PGF 2α (1 μ M ) plus GTPγS (50 μ M ) without affecting that induced by GTPγS alone. PGF 2α at 1 μ M transiently increased astrocytic intracellular Ca 2+ concentration in 39% of the cells tested. The response was completely blocked by 100 μ M phloretin and the calcium response recovered again after washing out phloretin. These results suggest that phloretin is an antagonist of PGF 2α receptor linked to phospholipase C in astrocytes.