Ergocryptine and other ergot alkaloids stimulate the release of (3H)dopamine from rat striatal synaptosomes

Citation metadata

Date: July 1999
From: Journal of Animal Science(Vol. 77, Issue 7)
Publisher: American Society of Animal Science
Document Type: Article
Length: 204 words

Document controls

Main content

Abstract :

Ergocryptine is an ergot alkaloid that affects dopaminergic activity principally by interacting with [D.sub.2]-type receptors. In this study the ability of ergocryptine and several other ergot alkaloids to release [3H]dopamine from isolated nerve endings was demonstrated using in vitro superfusion of rat striatal synaptosomes. Ergocryptine, ergocristine, and bromocryptine produced an elevation in baseline dopamine release of approximately 400% with effective concentrations ([EC.sub.50]) of approximately 30 [[micro]molar]. Ergotamine, ergonovine, ergovaline, and ergocornine were devoid of activity. The time-course of the ergocryptine-stimulated release was relatively slow compared with amphetamine, nicotine, or [K.sup.+]-stimulated [3H]dopamine release; the maximal increase in release required a 5-min treatment. A number of receptor antagonists were examined for their ability to block ergocryptine-stimulated release. Of the dopaminergic, adrenergic, serotonergic, GABA-ergic, and cholinergic antagonists examined, only phentolamine produced a moderate attenuation in evoked release. Omission of [Ca.sup.++] from the medium did not affect ergocryptine-evoked release. Following ergocryptine treatment, the synaptosomes were fully responsive to other stimulant. The results indicate that, in addition to interacting with dopamine receptors, several ergot alkaloids may produce dopaminergic effects by increasing the release of dopamine from central nerve endings. Several mechanisms to account for the evoked neurotransmitter release are discussed. Key Words: Ergot Alkaloids, Dopamine, Neurotransmitters, Rats, Receptors, Antagonists

Source Citation

Source Citation   

Gale Document Number: GALE|A55237114