title: Demonstration of presynaptic protein kinase C activation following long-term potentiation in rat hippocampal slices.
abstract: Pharmacological and biochemical evidence implicate the Ca2+ and phospholipid-dependent protein kinase C in long-term potentiation. The in vitro hippocampal slice preparation was used to demonstrate redistribution of protein kinase C from cytosol to membrane and protein kinase C-dependent phosphorylation of the presynaptic growth-associated protein-43 substrate following long-term potentiation induction in area CA1. Protein kinase C translocation was assessed using both quantitative immunoblotting with a monoclonal antibody recognizing a common epitope in the alpha and beta isoforms of protein kinase C and Ca2+ and phospholipid-dependent phosphorylation of exogenous histone substrate. Slices examined 5 min after tetanus-induced spike potentiation showed no change in protein kinase C redistribution, whereas slices examined at 15-, 30- and 60-min intervals all showed a similar degree of protein kinase C translocation to membrane, although only at 15 min was the effect statistically significant. Additionally, an increase in protein kinase C-dependent growth-associated protein 43 phosphorylation was observed 10 min after high-frequency stimulation. The translocation of protein kinase C and phosphorylation of growth-associated protein 43 were dependent upon high-frequency (repetitive 400 Hz) afferent stimulation, as no effects were observed in slices receiving low-frequency (1 Hz) or no stimulation. The N-methyl-D-aspartate receptor antagonist, DL-2-amino-5-phosphonovaleric acid (50 microM), inhibited induction of long-term potentiation, redistribution of protein kinase C and phosphorylation of growth-associated protein 43. A significant redistribution of the predominantly presynaptic protein kinase C isoform, protein kinase C-alpha, was also detected 15 min after induction of long-term potentiation using an alpha-isoform-specific monoclonal antibody. These observations support a presynaptic role for protein kinase C and growth-associated protein 43 in the early maintenance phase of LTP, and further suggest that a retrograde messenger produced postsynaptically following N-methyl-D-aspartate receptor activation mediates these effects.
authors.affiliation: Department of Pharmacology, State University of New York Health Science Center, Syracuse 13210-1605.
authors.forename: J C
authors.initials: JC
authors.lastname: Leahy
authors.forename: Y
authors.initials: Y
authors.lastname: Luo
authors.forename: C S
authors.initials: CS
authors.lastname: Kent
authors.forename: K F
authors.initials: KF
authors.lastname: Meiri
authors.forename: M L
authors.initials: ML
authors.lastname: Vallano
mesh_terms: D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000818:Animals; D002458:Cell Fractionation; D002462:Cell Membrane / Q000201:enzymology; D003600:Cytosol / Q000201:enzymology; D004558:Electric Stimulation; D004789:Enzyme Activation; D005071:Evoked Potentials / Q000502:physiology*; D019922:GAP-43 Protein; D006624:Hippocampus / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000032:analysis; D009419:Nerve Tissue Proteins / Q000032:analysis; D010750:Phosphoproteins / Q000032:analysis; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D011712:Pyramidal Tracts / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors; D013569:Synapses / Q000502:physiology*
chemical_list: D019922:GAP-43 Protein; D007527:Isoenzymes; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D010750:Phosphoproteins; D016194:Receptors, N-Methyl-D-Aspartate; D015763:2-Amino-5-phosphonovalerate; D011493:Protein Kinase C