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Modulation of postsynaptic potentials in rat cortical neurons by valerian extracts macerated with different alcohols: involvement of adenosine A 1 ‐ and GABA A ‐receptors
Author(s) -
Sichardt K.,
Vissien Z.,
Koetter U.,
Brattström A.,
Nieber K.
Publication year - 2007
Publication title -
phytotherapy research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.019
H-Index - 129
eISSN - 1099-1573
pISSN - 0951-418X
DOI - 10.1002/ptr.2197
Subject(s) - valerian , postsynaptic potential , pharmacology , picrotoxin , gabaa receptor , adenosine , chemistry , receptor , biology , biochemistry
Valeriana officinalis (valerian) is used traditionally as a mild sedative. Research into valerian is sparse, and studies differ greatly with respect to design, measures and preparations used. This study compares the action of a methanol (M‐E), ethanol (E‐E) and an extract macerated with ethylacetate (EA‐E) from roots of valerian ( Valeriana officinalis L., Valerianaceae) on postsynaptic potentials (PSPs) in cortical neurons. Intracellular recordings were performed in rat brain slice preparations containing pyramidal cells of the cingulate cortex. PSPs were induced by electrical field stimulation. The M‐E induced strong inhibition in the concentration range 0.1–15 mg/mL, whereas the E‐E (1–10 mg/mL) did not influence significantly the PSPs. The maximum inhibition induced by the M‐E was completely antagonized by 1,3‐dipropyl‐8‐cyclopentylxanthine (DPCPX, 0.1 µ m ), an antagonist on the adenosine A 1 receptor. Contrary to the M‐E, the EA‐E (10 mg/mL) induced an increase of the PSPs, which was completely blocked by the GABA A receptor antagonist picrotoxin (100 µ m ). The data suggest that activation of adenosine A 1 and GABA A receptors is mediated by different components within the valerian extract. The two mechanisms may contribute independently to the sleep‐inducing effect of valerian. Copyright © 2007 John Wiley & Sons, Ltd.