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Titolo:
LOBELINE DISPLACES [H-3]DIHYDROTETRABENAZINE BINDING AND RELEASES [H-3]DOPAMINE FROM RAT STRIATAL SYNAPTIC VESICLES - COMPARISON WITH D-AMPHETAMINE
Autore:
TENG LH; CROOKS PA; DWOSKIN LP;
Indirizzi:
UNIV KENTUCKY,COLL PHARM,ROSE ST LEXINGTON KY 40536 UNIV KENTUCKY,COLL PHARM LEXINGTON KY 40536 UNIV KENTUCKY,GRAD CTR TOXICOL LEXINGTON KY 40536
Titolo Testata:
Journal of neurochemistry
fascicolo: 1, volume: 71, anno: 1998,
pagine: 258 - 265
SICI:
0022-3042(1998)71:1<258:LD[BAR>2.0.ZU;2-0
Fonte:
ISI
Lingua:
ENG
Soggetto:
VESICULAR MONOAMINE TRANSPORTER; CONDITIONED PLACE PREFERENCE; NICOTINIC RECEPTORS; CHROMAFFIN GRANULES; DOPAMINE RELEASE; MOUSE-BRAIN; DIHYDROTETRABENAZINE-BINDING; LOCOMOTOR STIMULANT; ELECTRON-TRANSFER; UP-REGULATION;
Keywords:
DOPAMINE; LOBELINE; DIHYDROTETRABENAZINE; VESICULAR MONOAMINE TRANSPORTER;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
75
Recensione:
Indirizzi per estratti:
Citazione:
L.H. Teng et al., "LOBELINE DISPLACES [H-3]DIHYDROTETRABENAZINE BINDING AND RELEASES [H-3]DOPAMINE FROM RAT STRIATAL SYNAPTIC VESICLES - COMPARISON WITH D-AMPHETAMINE", Journal of neurochemistry, 71(1), 1998, pp. 258-265

Abstract

Lobeline, an alkaloid from Indian tobacco (Lobelia inflata), is classified as a nicotinic agonist and is currently used as a smoking cessation agent. However, our previous in vitro studies demonstrate that lobeline does not act as a nicotinic agonist but alters presynaptic dopamine (DA) storage by potently inhibiting DA uptake into synaptic vesicles. Recently, d-amphetamine has been reported to act at the level of the synaptic vesicle to alter presynaptic function. The present in vitro studies further elucidate the mechanism of lobeline's action and compare its effects with those of d-amphetamine. [H-3]- Dihydrotetrabenazine ([H-3]DTBZ), used routinely to probe a high-affinity binding site on the vesicular monoamine transporter (VMAT2), bound to vesicle membranes from rat striatum with a K-D of 1.67 nM and B-max of 8.68 pmol/mgof protein. Lobeline inhibited [H-3]DTBZ binding with an IC50 of 0.90mu M, consistent with its previously reported IC50 Of 0.88 mu M for inhibition of [H-3]DA uptake into vesicles. These results suggest that lobeline specifically interacts with DTBZ sites on VMAT2 to inhibit DAuptake into synaptic vesicles. Interestingly, d-amphetamine inhibited[H-3]DTBZ binding to vesicle membranes with an IC50 of 39.4 mu M, a concentration 20 times greater than reported for inhibition of VMAT2 function, suggesting that d-amphetamine interacts with a different site than lobeline on VMAT2 to inhibit monoamine uptake. Kinetic analysis of [H-3]DA release from [H-3]DA-preloaded synaptic vesicles in the absence of drug revealed a t(1/2), of 2.12 min. Lobeline and d-amphetamineevoked [H-3]DA release with ECS, values of 25.3 and 2.22 mu M, respectively. At a concentration 10 times the EC50, lobeline and d-amphetamine significantly decreased the t(1/2) of [H-3]DA release to 1.58 and 1.48 min, respectively. Thus, in contrast to d-amphetamine, which is equipotent in inhibiting DA uptake and promoting release from the synaptic vesicles, lobeline more potently (28-fold) inhibits DA uptake (via an interaction with the DTBZ site on VMAT2) than it evokes DA release to redistribute presynaptic DA storage.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 02/04/20 alle ore 11:33:20