Differential effects of novel wasp toxin on rat hippocampal interneurons.
We studied the effects of a wasp toxin beta-pompilidotoxin (beta-PMTX) on rat hippocampal CA1 interneurons by the current-clamp technique. The firing patterns of pyramidal neurons and pyramidale interneurons were not affected by beta-PMTX, but in oriens and radiatum interneurons, beta-PMTX converted the action potentials to prolonged depolarizing potentials by slowing the inactivation of Na(+) channels. In lacunosum moleculare interneurons, beta-PMTX induced initial bursting spikes followed by block of succeeding spikes. Comparison of beta-PMTX with a sea anemone toxin, ATX II, revealed that ATX II altered the firing properties of pyramidal neurons and pyramidale interneurons that were unchanged by beta-PMTX. Our results suggest that beta-PMTX modulates Na(+) currents in CA1 interneurons differently in various CA1 neurons and the toxin is useful to classify Na(+) channel subtypes.
Department of Surgical Neurology, Jichi Medical School, Minamikawachi-machi, Tochigi 329-0498, Japan. tmiyawaki@jichi.ac.jp
Takahiro
T
Miyawaki
Hiroshi
H
Tsubokawa
Hidenori
H
Yokota
Keiji
K
Oguro
Katsuhiro
K
Konno
Toshio
T
Masuzawa
Nobuhumi
N
Kawai
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D003064:Cnidarian Venoms / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D019476:Insect Proteins; D007395:Interneurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology*; D009434:Neural Pathways / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D009498:Neurotoxins / Q000494:pharmacology*; D009924:Organ Culture Techniques; D017966:Pyramidal Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D015222:Sodium Channels / Q000187:drug effects / Q000378:metabolism*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D014862:Wasp Venoms
D003064:Cnidarian Venoms; D019476:Insect Proteins; D009498:Neurotoxins; D015222:Sodium Channels; D014862:Wasp Venoms; C115329:pompilidotoxin beta; C028800:toxin II (Anemonia sulcata)