Long-term synaptic transformation of hippocampal CA1 gamma-aminobutyric acid synapses and the effect of anandamide.
Evidence is presented for a distinctive type of hippocampal synaptic modification [previously described for a molluscan gamma-aminobutyric acid (GABA) synapse after paired pre- and postsynaptic excitation]: transformation of GABA-mediated synaptic inhibition into synaptic excitation. This transformation persists with no further paired stimulation for 60 min or longer and is termed long-term transformation. Long-term transformation is shown to contribute to pairing-induced long-term potentiation but not to long-term potentiation induced by presynaptic stimulation alone. Further support for such mechanistic divergence is provided by pharmacologic effects on long-term transformation as well as these two forms of long-term potentiation by Cl- channel blockers, glutamate and GABA antagonists, as well as the endogenous cannabinoid ligand anandamide.
D000818:Animals; D001095:Arachidonic Acids / Q000494:pharmacology*; D001418:Baclofen / Q000031:analogs & derivatives / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D018118:Chloride Channels / Q000037:antagonists & inhibitors; D063388:Endocannabinoids; D005665:Furosemide / Q000494:pharmacology; D006624:Hippocampus / Q000502:physiology*; D066298:In Vitro Techniques; D017774:Long-Term Potentiation / Q000187:drug effects* / Q000502:physiology; D008297:Male; D008959:Models, Neurological; D053284:Polyunsaturated Alkamides; D017966:Pyramidal Cells / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012908:Snails; D013569:Synapses / Q000187:drug effects / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology* / Q000502:physiology*
D001095:Arachidonic Acids; D002121:Calcium Channel Blockers; D018118:Chloride Channels; D063388:Endocannabinoids; D053284:Polyunsaturated Alkamides; C052329:phaclofen; D005680:gamma-Aminobutyric Acid; D005665:Furosemide; D001418:Baclofen; C078814:anandamide