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GABA‐like Actions of Levonantradol
Author(s) -
LEADER JOAN P.,
KOE B. KENNETH,
WEISSMAN ALBERT
Publication year - 1981
Publication title -
the journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.92
H-Index - 116
eISSN - 1552-4604
pISSN - 0091-2700
DOI - 10.1002/j.1552-4604.1981.tb02604.x
Subject(s) - pharmacology , chemistry , medicine
The interaction of levonantradol and its pharmacologically less active (+)‐enantiomer with GABAergic mechanisms was studied in several in vivo systems: (1) rat cerebellar cGMP, based on the inverse relationship of GABAergic activity and cGMP levels; (2) convulsions elicited by 3‐mercaptopropionic acid, an inhibitor of GABA synthesis; and (3) activated dopamine synthesis in rat striatum following blockade of dopamine receptors. Levonantradol decreased rat cerebellar cGMP content at low doses (1.0 mg/kg intraperitoneally) and antagonized elevation of cGMP levels by the GABA biosynthesis inhibitor isoniazid at even lower doses (0.32 mg/kg intraperitoneally); this activity pattern is suggestive of GABAergic activity. This conclusion is also supported by levonantradol's protection of mice against the convulsant effects of 3‐mercaptopropionic acid. GABAergic agents are known to antagonize the enhanced dopamine synthesis and turnover that accompany dopamine receptor blockade by neuroleptics. Levonantradol (0.047 mg/kg intravenously) stereospecifically attenuated the elevated dopa accumulation induced by haloperidol. Levonantradol is at least 100‐fold more active than THC in blocking isoniazid‐induced elevation of cGMP levels in rat cerebellum or haloperidol‐induced enhanced dopa accumulation in rat striatum.