Omega-conotoxin GVIA blocks synaptic transmission in the CA1 field of the hippocampus.
The effects of omega-conotoxin GVIA (omega-CgTx), a peptide isolated from the venom of a marine mollusc, were studied in rat hippocampal neurons. Intracellular recordings from the CA1 area were made for the purpose in in vitro slice preparations. Omega-CgTx (0.1-1 microM) rapidly and irreversibly blocked the EPSP and the IPSPs elicited by electrical stimulation of Schaffer collaterals/commissural fibers. Omega-CgTx also blocked the slow cholinergic EPSP induced by electrical stimulation of cholinergic afferents. The postsynaptic effects of baclofen or carbachol remained unchanged in the presence of omega-CgTx and other postsynaptic calcium-dependent events such as afterhyperpolarization were not affected by omega-CgTx. These results suggest a presynaptic action of omega-CgTx through the blockade of neurotransmitter release. Omega-CgTx might act in the hippocampus by blocking presynaptic N-type voltage-sensitive calcium channels.
Dutar
P
P
Laboratoire de Physiopharmacologie du Système Nerveux, INSERM U161, Paris, France.
Rascol
O
O
Lamour
Y
Y
D000818:Animals; D002118:Calcium / Q000502:physiology; D005071:Evoked Potentials / Q000187:drug effects; D006624:Hippocampus / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D008978:Mollusk Venoms / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013569:Synapses / Q000187:drug effects*; D009435:Synaptic Transmission / Q000187:drug effects*; D020866:omega-Conotoxin GVIA
D008978:Mollusk Venoms; D020866:omega-Conotoxin GVIA; D002118:Calcium