Barbiturate effects on hippocampal excitatory synaptic responses are selective and pathway specific.
Barbiturate actions on excitatory synaptic responses in CA 1 and dentate regions of hippocampal slices were studied to determine whether different effects occur on anatomically distinct synaptic pathways. Pentobarbital facilitated transmission between stratum radiatum inputs and CA 1 neurons at low concentrations (0.02-0.08 mM) and produced postsynaptic depression at higher concentrations. Only depression was observed for stratum oriens inputs to CA 1 and perforant path inputs to dentate granulae neurons. The (+) isomer of pentobarbital was approximately four times more potent than the (-) isomer of racemic mixture. Phenobarbital (0.04-0.12 mM) produced only depression of synaptic responses in CA 1 and dentate pathways. Comparison of effect on field excitatory postsynaptic potentials and population spike responses indicated that the barbiturates act at selective and pathway-specific sites. The results provide further evidence for specific cellular and membrane recognition sites for barbiturate action.
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001463:Barbiturates / Q000494:pharmacology*; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D008297:Male; D009434:Neural Pathways / Q000187:drug effects / Q000502:physiology; D010424:Pentobarbital / Q000494:pharmacology; D010634:Phenobarbital / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013569:Synapses / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects
D001463:Barbiturates; D010424:Pentobarbital; D010634:Phenobarbital