Potassium-induced long-term potentiation in area CA1 of the hippocampus involves phospholipase activation.
Previous studies have shown that potassium-induced long-term potentiation (LTP) of the Schaffer collateral/commissural synapses in area CA1 of the hippocampus shares common properties with tetanus-induced LTP. In the present investigation, we performed electrophysiological and binding experiments on CA1 hippocampal slices to evaluate the location and nature of the changes underlying potassium-induced LTP. Paired-pulse facilitation, which represents an index of transmitter release, was markedly reduced by potassium-induced LTP. In addition, KCl-induced LTP was associated with an increase in 3H-AMPA ([3H]-amino-3-hydroxy-5-methylisoxazole-4-propionate) binding to CA1 synaptic membranes when measured 40 min after high-potassium exposure; however, no changes were detected in binding of an antagonist ([3H]-6-cyano-7-nitroquinoxaline-2,3-dione; 3H-CNQX) to AMPA receptors in slices expressing KCl-induced LTP. Administration of the phospholipase A2 (PLA2) inhibitor bromophenacyl bromide (BPB) prior to potassium application prevented LTP formation as well as the changes in paired-pulse facilitation and 3H-AMPA binding that characterized this type of potentiation. Taken together, these data indicate that potassium-induced LTP may be related to modifications in both pre- and postsynaptic properties and confirm the hypothesis that PLA2 activation is an important mechanism in long-term changes of synaptic operation.
Bernard
J
J
Départment de Chimie-Biologie, Université du Québec à Trois-Rivières, Canada.
Lahsaini
A
A
Massicotte
G
G
D000098:Acetophenones / Q000494:pharmacology; D000818:Animals; D004789:Enzyme Activation / Q000187:drug effects; D006624:Hippocampus / Q000033:anatomy & histology / Q000187:drug effects* / Q000502:physiology*; D066298:In Vitro Techniques; D017774:Long-Term Potentiation / Q000187:drug effects* / Q000502:physiology*; D008297:Male; D010741:Phospholipases A / Q000037:antagonists & inhibitors / Q000378:metabolism*; D054467:Phospholipases A2; D011189:Potassium Chloride / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000187:drug effects / Q000378:metabolism
D000098:Acetophenones; D018091:Receptors, AMPA; D011189:Potassium Chloride; D010741:Phospholipases A; D054467:Phospholipases A2; C006821:4-bromophenacyl bromide