The EPSP-spike (E-S) component of long-term potentiation in the rat hippocampal slice is modulated by GABAergic but not cholinergic mechanisms.
Long-term potentiation of synaptic efficacy (LTP) can be shown to consist of two components: a synaptic and an excitatory postsynaptic potential (EPSP)-spike (E-S) component. The E-S component is expressed as a leftward shift in the curve relating population spike amplitude as a function of EPSP slope. The participation of cholinergic and GABAergic processes in E-S potentiation was studied in field CA1 of rat hippocampal slices. Atropine, a muscarinic antagonist, did not prevent tetanus-induced E-S potentiation. The cholinergic agonist carbachol and the GABAA antagonist picrotoxin produced a leftward shift in the E-S relation; picrotoxin, but not carbachol, prevented the expression of tetanus-induced E-S potentiation. These observations indicate that an increase in the ratio of evoked excitation to inhibition and/or a reduction in tonic inhibition mediated by the activation of GABAA receptors contribute to E-S potentiation produced by high-frequency stimulation.
Chavez-Noriega
L E
LE
Division of Neurophysiology and Neuropharmacology, National Institute for Medical Research, London, U.K.
Bliss
T V
TV
Halliwell
J V
JV
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D004558:Electric Stimulation; D006624:Hippocampus / Q000502:physiology*; D008297:Male; D010852:Picrotoxin / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011950:Receptors, Cholinergic / Q000502:physiology*; D011963:Receptors, GABA-A / Q000502:physiology*; D011976:Receptors, Muscarinic / Q000502:physiology; D013569:Synapses / Q000502:physiology*
D001285:Atropine; D002217:Carbachol; D010852:Picrotoxin; D011950:Receptors, Cholinergic; D011963:Receptors, GABA-A; D011976:Receptors, Muscarinic