Long-term effects of an Apocynum venetum extract on brain monoamine levels and beta-AR density in rats.
The present study was designed to get further insight into the mode of antidepressant action of an extract prepared of the leaves of Apocynum venetum L. (AV). To evaluate biochemical changes, we used a high-performance liquid chromatography system to examine the effects of short-term (2 weeks) and long-term (8 weeks) administration of imipramine (15 mg/kg po) and an AV-extract (15, 60 and 250 mg/kg) on regional levels of serotonin (5-HT), norepinephrine (NE), dopamine (DA) and their metabolites in the rat hypothalamus, striatum and hippocampus. Pronounced changes in 5-HT, NE and DA levels were detected mainly after 8 weeks of daily imipramine treatment. Similar to imipramine, AV-extract reduced NE and DA concentrations after 8 weeks, whereas it failed to affect 5-HT levels. We speculate that the decrease in NE levels after chronic AV treatment might be based partly on the subsensitivity of presynaptic alpha(2)-receptors. In addition to the determination of central monoamine concentrations, quantitative radioligand receptor-binding studies were used to examine the effects of long-term administration of imipramine and AV-extract on beta-adrenergic binding in rat frontal cortex. [125I]CYP binding to beta-adrenergic receptors was found to be decreased after 8 weeks treatment with imipramine, whereas AV-extract had no effect on beta-receptor binding.
Butterweck
Veronika
V
Institute of Pharmacology and Toxicology, Universitätsklinikum Muenster, Domagkstrasse 12, 48149 Münster, Germany. butterv@uni-muenster.de
Simbrey
Kirsten
K
Seo
Shujiro
S
Sasaki
Tsutomu
T
Nishibe
Sansei
S
D000818:Animals; D030010:Apocynum; D015306:Biogenic Monoamines / Q000378:metabolism*; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D010936:Plant Extracts / Q000378:metabolism / Q000494:pharmacology; D018515:Plant Leaves; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D013995:Time
D015306:Biogenic Monoamines; D010936:Plant Extracts; D011943:Receptors, Adrenergic, beta