Modulatory effects of magnolol on potassium-stimulated 5-hydroxytryptamine release from rat cortical and hippocampal slices.
Magnolol, a phenolic constituent of magnolia bark, is a known central nervous system depressant. To examine the possibility that magnolol may elicit its depressant effect by modulating central serotonergic activity, its effect on 35 mM K(+)-stimulated 5-[3H]HT release from rat hippocampal and frontal cortical slices were examined. Inclusion of magnolol (1-100 microM) had no effect on 5-HT release in hippocampal slices but elicited a dose-related inhibition on 5-HT release from cortical slices. The inhibitory effect of magnolol on K(+)-stimulated 5-HT release from the cortex was not affected by either antagonists (metergoline, propranolol, and cyproheptadine) (0.01-10 microM) of various 5-HT receptor subtypes or the voltage-dependent sodium channel blocker tetrodotoxin (1 microM). It is concluded that the suppression of brain 5-HT release by magnolol is site-specific, and the suppression of cortical 5-HT release by magnolol is not via the 5-HT autoreceptors at the 5-HT terminals.
Tsai
T H
TH
Department of Pharmacology, National Yang-Ming Medical College, Taipei, Taiwan, Republic of China.
Lee
T F
TF
Chen
C F
CF
Wang
L C
LC
D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D001713:Biphenyl Compounds / Q000494:pharmacology*; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism*; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D066298:In Vitro Techniques; D017705:Lignans; D008297:Male; D011188:Potassium / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011985:Receptors, Serotonin / Q000187:drug effects / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism*; D012702:Serotonin Antagonists / Q000494:pharmacology
D000972:Antineoplastic Agents, Phytogenic; D001713:Biphenyl Compounds; D017705:Lignans; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; C005498:magnolol; D012701:Serotonin; D011188:Potassium