Synaptic strength at the thalamocortical input to layer IV neonatal barrel cortex is regulated by protein kinase C.
Long-term synaptic plasticity is an important mechanism underlying the development of cortical circuits in a number of brain regions. In barrel cortex NMDA receptor (NMDAR)-dependent long-term potentiation (LTP) and long-term depression (LTD) play a critical role in the development and experience-dependent plasticity of the topographical map of the rodent whiskers. However, the mechanisms underlying the induction and expression of these forms of plasticity are poorly characterised. Here we investigate the role of PKC in the regulation of synaptic strength in neonatal barrel cortex using patch-clamp recordings in brain slices. We demonstrate that PKC activity tonically maintains AMPA receptor-mediated transmission at thalamocortical synapses, and that basal transmission can be potentiated by PKC activation using postsynaptic infusion of phorbol ester. Furthermore, we show that induction of NMDAR-dependent LTP requires PKC activity. These findings demonstrate that PKC is required for the regulation of transmission at thalamocortical synapses, the major ascending sensory input to barrel cortex. Thalamocortical inputs in barrel cortex only express LTP during the first postnatal week during a critical period for experience-dependent plasticity in layer IV. Therefore, the requirement for PKC in LTP suggests an important role for this kinase in the development of the barrel cortex sensory map.
Scott
Helen L
HL
MRC Centre for Synaptic Plasticity, Department of Anatomy, University of Bristol, University Walk, Bristol BS8 1TD, UK.
Braud
Stephanie
S
Bannister
Neil J
NJ
Isaac
John T R
JT
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D053119:Benzophenanthridines / Q000494:pharmacology; D001640:Bicuculline / Q000494:pharmacology; D004307:Dose-Response Relationship, Radiation; D004558:Electric Stimulation / Q000379:methods; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D018756:GABA Antagonists / Q000494:pharmacology; D066298:In Vitro Techniques; D051379:Mice; D019579:Neocortex / Q000166:cytology*; D009434:Neural Pathways / Q000502:physiology; D009474:Neurons / Q000502:physiology / Q000648:ultrastructure*; D018408:Patch-Clamp Techniques / Q000379:methods; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D011493:Protein Kinase C / Q000494:pharmacology*; D013569:Synapses / Q000187:drug effects* / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D013788:Thalamus / Q000502:physiology*
D000470:Alkaloids; D053119:Benzophenanthridines; D004791:Enzyme Inhibitors; D018691:Excitatory Amino Acid Antagonists; D018756:GABA Antagonists; D015240:Phorbol 12,13-Dibutyrate; D015763:2-Amino-5-phosphonovalerate; C016299:chelerythrine; D011493:Protein Kinase C; D001640:Bicuculline