Antagonism of glutamate receptors by a chromatographic fraction from the exudate of the sea anemone Phyllactis flosculifera.
In the search for new glutamate antagonists it seems promising to characterize the effects of venom from invertebrates that prey mainly on crustaceans. In this work, the exudate of the sea anemone Phyllactis flosculifera was used as a source of this type of compound. The action of chromatographic fraction D from P. flosculifera was tested upon microion-tophoretically evoked glutamate responses in intracellular recordings from central neurons of the land snail Zachrysia guanensis. Bath application of fraction D (2-8 mg/ml, n = 13) diminished both the excitatory and the inhibitory components of glutamate agonists in Z. guanensis neurons; this action was dose-dependent and partially reversible. Fraction D actions were also tested in the multiunit spontaneous and mechanically evoked responses of the glutamatergic junction between hair cells and afferent neurons of the axolotl Ambystoma tigrinum. Pressure ejection of fraction D in concentrations ranging from 0.5 to 2 mg/ml (n = 9) decreased the spontaneous and mechanically evoked activity of semicircular canal afferent neurons and the responses evoked by kainic acid and alpha-amino-3-hydroxy-5-methylisoxasole-4-propionic acid. This action was also dose-dependent and partially reversible. These results indicate that fraction D acts as a glutamate receptor antagonist in snail and amphibian neurons. Further studies are required to characterize the active compounds responsible for this action and its specificity upon the subtypes of glutamate receptors.
Garateix
A
A
Centro de Bioactivos Marinos, Ministerio de Ciencia, Tecnología y Medio Ambiente, la Habana Cuba.
Flores
A
A
García-Andrade
J M
JM
Palmero
A
A
Aneiros
A
A
Vega
R
R
Soto
E
E
D000557:Ambystoma; D000818:Animals; D005591:Chemical Fractionation; D002850:Chromatography, Gel; D003064:Cnidarian Venoms / Q000378:metabolism / Q000633:toxicity*; D003051:Cochlea / Q000187:drug effects / Q000378:metabolism; D018691:Excitatory Amino Acid Antagonists / Q000378:metabolism / Q000633:toxicity*; D007478:Iontophoresis; D007608:Kainic Acid / Q000633:toxicity; D009412:Nerve Fibers / Q000187:drug effects / Q000378:metabolism; D009475:Neurons, Afferent / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D016318:Quisqualic Acid / Q000633:toxicity; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects; D012615:Sea Anemones / Q000378:metabolism*; D012908:Snails; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000633:toxicity
D003064:Cnidarian Venoms; D018691:Excitatory Amino Acid Antagonists; D016194:Receptors, N-Methyl-D-Aspartate; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; D016318:Quisqualic Acid; D007608:Kainic Acid