Critical involvement of postsynaptic protein kinase activation in long-term potentiation at hippocampal mossy fiber synapses on CA3 interneurons.
J Neurosci
; 30(8): 2844-55, 2010 Feb 24.
Article
en En
| MEDLINE
| ID: mdl-20181582
Hippocampal mossy fiber (MF) synapses on area CA3 lacunosum-moleculare (L-M) interneurons are capable of undergoing a Hebbian form of NMDA receptor (NMDAR)-independent long-term potentiation (LTP) induced by the same type of high-frequency stimulation (HFS) that induces LTP at MF synapses on pyramidal cells. LTP of MF input to L-M interneurons occurs only at synapses containing mostly calcium-impermeable (CI)-AMPA receptors (AMPARs). Here, we demonstrate that HFS-induced LTP at these MF-interneuron synapses requires postsynaptic activation of protein kinase A (PKA) and protein kinase C (PKC). Brief extracellular stimulation of PKA with forskolin (FSK) alone or in combination with 1-Methyl-3-isobutylxanthine (IBMX) induced a long-lasting synaptic enhancement at MF synapses predominantly containing CI-AMPARs. However, the FSK/IBMX-induced potentiation in cells loaded with the specific PKA inhibitor peptide PKI(6-22) failed to be maintained. Consistent with these data, delivery of HFS to MFs synapsing onto L-M interneurons loaded with PKI(6-22) induced posttetanic potentiation (PTP) but not LTP. Hippocampal sections stained for the catalytic subunit of PKA revealed abundant immunoreactivity in interneurons located in strata radiatum and L-M of area CA3. We also found that extracellular activation of PKC with phorbol 12,13-diacetate induced a pharmacological potentiation of the isolated CI-AMPAR component of the MF EPSP. However, HFS delivered to MF synapses on cells loaded with the PKC inhibitor chelerythrine exhibited PTP followed by a significant depression. Together, our data indicate that MF LTP in L-M interneurons at synapses containing primarily CI-AMPARs requires some of the same signaling cascades as does LTP of glutamatergic input to CA3 or CA1 pyramidal cells.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Proteínas Quinasas
/
Potenciación a Largo Plazo
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Transmisión Sináptica
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Fibras Musgosas del Hipocampo
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Región CA3 Hipocampal
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Interneuronas
Idioma:
En
Revista:
J Neurosci
Año:
2010
Tipo del documento:
Article
País de afiliación:
Estados Unidos
Pais de publicación:
Estados Unidos