title: Effects of alpha-scorpion toxin, tityustoxin on the release of [3H] dopamine of rat brain prefrontal cortical slices.
abstract: The effect of tityustoxin (TsTX) on the release of [3H] dopamine in rat brain prefrontal cortical slices was investigated. The stimulatory effect of TsTX was dependent on incubation time and TsTX concentration with an EC50 of 0.05 microM. The release of [3H] dopamine stimulated by TsTX is dependent of Na+ channels and thus, was completely, inhibited by tetrodotoxin. Tityustoxin-induced release of [3H] dopamine was not blocked by ethylene glycol-bis(beta-aminoethyl) ether (EGTA) and thus was independent of extracellular calcium. However, [3H] dopamine release induced by TsTX was inhibited by 52% by BAPTA, a calcium chelator. Moreover, dantrolene (100 microM) and tetracaine (500 microM) partially inhibited by 38 and 29%, respectively, the tityustoxin-induced release of [3H] dopamine from prefrontal cortical slices suggesting a role from intracellular calcium increase. In conclusion, part of the TsTX-induced release [3H] dopamine may be due to an effect of the toxin on the reversal of the dopamine transporter (DAT), but the majority of the toxin stimulated release of [3H] dopamine involves the mobilization of intracellular calcium stores.
authors.affiliation: PUC Belo Horizonte, MG, Brazil.
authors.forename: Virginia M V
authors.initials: VM
authors.lastname: Fernandes
authors.forename: André R
authors.initials: AR
authors.lastname: Massensini
authors.forename: Marco Antonio M
authors.initials: MA
authors.lastname: Prado
authors.forename: Marco Aurélio Romano
authors.initials: MA
authors.lastname: Silva
authors.forename: Tasso
authors.initials: T
authors.lastname: Moraes-Santos
authors.forename: Marcus Vinicius
authors.initials: MV
authors.lastname: Gomez
mesh_terms: D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002614:Chelating Agents / Q000494:pharmacology; D003620:Dantrolene / Q000494:pharmacology; D004298:Dopamine / Q000378:metabolism*; D004533:Egtazic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D004558:Electric Stimulation; D005089:Exocytosis / Q000187:drug effects; D066298:In Vitro Techniques; D009125:Muscle Relaxants, Central / Q000494:pharmacology; D009498:Neurotoxins / Q000302:isolation & purification / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology; D017397:Prefrontal Cortex / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012604:Scorpion Venoms / Q000302:isolation & purification / Q000494:pharmacology*; D013748:Tetracaine / Q000494:pharmacology
chemical_list: D000779:Anesthetics, Local; D002614:Chelating Agents; D009125:Muscle Relaxants, Central; D009498:Neurotoxins; D012604:Scorpion Venoms; D013748:Tetracaine; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; C003609:tityustoxin; D004533:Egtazic Acid; D003620:Dantrolene; D011188:Potassium; D002118:Calcium; D004298:Dopamine