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Schorderet M, Sovilla JY, Magistretti PJ. 
“New Findings Related To A Possible Interaction Of Ergolines And Ergopeptines With Pre-synaptic Dopmine Receptors”. 
Progress in Neuro-Psychopharmacology. 1980 Jun 22-26;? (Supp. 1):315.
Three different techniques in vitro and/or in vivo were applied to investigate the type(s) of interaction(s) of ergot alkaloids, including d-LSD, with CNS dopamine receptors. 1) Rabbit retinae in vitro were used to test potential dopamine agonist- and or antagonist-activity of a synthetic derivative, meter-goline, by measuring the formation of cAMP in intact- or homogenized-tissue. As shown previously for bromocriptine and for several other ergot alkaloids (Neurosci.Lett. 2,87,1976, Gerontology 24,86,1978), metergoline was also able to stimulate cAMP formation in intact retina. However, in contrast with other tested compounds, metergoline also stimulated the formation of cAMP in retinal homogenates in a dose-dependent manner and partially antagonized, at 10-4 M, the agonist effect of 10-5 M dopamine. A selective site of action of metergoline can be envisaged, since its agonist effect was blocked by fluphenazine or haloperidol in a dose-dependent manner, but not by (+)-butaclamol or cis-flupenthixol. Phenothiazines or butyrophenones are known to act at both pre and post-synaptic dopamine receptors, whereas butaclamol or thioxanthenes are supposed to act preferentially at post-synaptic receptors. 2) Bovine retinae were used for binding- and displacement-studies of 3H-spiroperidol (Life Sci. - 25,1675,1979). Ergot alkaloids were found to be as potent displacing agents as several neuroleptics and much more potent than dopamine or other dopamine analogs. 3) Finally, the climbing behaviour in mice was applied to investigate a possible action of ergot alkaloids at pre-synaptic sites, as shown previously for d-LSD, which was able to potentiate the effects of apomorphine (Prog. Neuro-Psychopharmacol. 3, 1979). Taken together, our results would suggest a selectivity of some ergopeptines and/or ergolines for dopamine presynaptic receptors, whose interactions with these agents influence the dopaminergic activity of the CNS in various pathological states.
Notes # : 12th Congress of the Collegium Internationale Neuro-Pharmacologium (CINP) Abstr. No. 603
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