Philanthotoxin-343 blocks long-term potentiation in rat hippocampus.
The effects of extracellularly-applied synthetic philanthotoxin-343 (PhTX-343) on transmission and long-term potentiation (LTP) at Schaffer-collateral/commissural-CA1 synapses were investigated. PhTX-343 was ineffective in antagonizing CA1 field-EPSPs mediated by AMPA/kainate receptors. However, when a micromolar concentration of the toxin was present during tetanization, the induction of LTP was suppressed. In contrast, when PhTX-343 was applied either immediately after or long after tetanization no effect on LTP could be found. It appears that the synaptic, non-NMDA receptors of the CA1-region are insensitive to PhTX-343. Suppression of LTP induction could result from antagonism of postsynaptic NMDA receptors, but the results do not rule out other possibilities such as presynaptic block.
Matthies
H
H
Institute of Neurobiology, Magdeburg, Germany.
Brackley
P T
PT
Usherwood
P N
PN
Reymann
K G
KG
D000818:Animals; D005071:Evoked Potentials / Q000187:drug effects; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D011073:Polyamines; D011712:Pyramidal Tracts / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D011984:Sensory Receptor Cells / Q000187:drug effects / Q000502:physiology; D013569:Synapses / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors; D014862:Wasp Venoms / Q000494:pharmacology*
D011073:Polyamines; D014862:Wasp Venoms; C034092:delta-philanthotoxin