title: Postsynaptic kinase signaling underlies inhibitory synaptic plasticity in the lateral superior olive.
abstract: In the auditory system, inhibitory transmission from the medial nucleus of the trapezoid body (MNTB) to neurons of the lateral superior olivary nucleus (LSO) undergoes activity-dependent long-term depression, and may be associated with developmental elimination of these synapses [Sanes DH, Friauf E (2000).
  
  
  METHODS
  development and influence of inhibition in the laterial superior olivary nucleus. Hear Res 147:46-58]. Although GABA(B) receptor activation and postsynaptic free calcium are implicated in this depression, little is known about intracellular signaling mechanisms in this or other forms of inhibitory plasticity. In this study, we asked whether the calcium dependency of inhibitory depression was associated with the activation of calcium/calmodulin-dependent protein kinase II (CaMKII), protein kinase C (PKC), and/or cAMP-dependent protein kinase A (PKA). Whole-cell voltage-clamp recordings were obtained from LSO neurons in a brain slice preparation, permitting for the selective pharmacologic manipulation of individual postsynaptic LSO neurons. Inclusion of a CaMKII antagonist (KN-62) in the internal pipet solution blocked inhibitory synaptic depression. A second CaMKII inhibitor (autocamtide peptide fragment) significantly decreased inhibitory depression. Inclusion of a specific antagonist of protein kinase C (PKC fragment 19-36) in the internal recording solution also blocked inhibitory depression. To test involvement of a cAMP-dependent intracellular cascade, two different manipulations were performed. Inclusion of PKA antagonists (Rp-cAMPS or a cAMP dependent protein kinase inhibitor peptide) prevented inhibitory depression. In contrast, when a nonhydrolyzable cAMP analog (Sp-cAMPS) was permitted to enter the postsynaptic cell, the MNTB-evoked IPSCs became depressed in the absence of low-frequency stimulation. Thus, three key postsynaptic kinases, CaMKII, PKC, and PKA, participate in the activity-dependent depression of inhibitory MNTB-LSO synapses during postnatal development.
mesh_terms: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D000242:Cyclic AMP / Q000031:analogs & derivatives* / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005849:Gerbillinae; D036881:Long-Term Synaptic Depression / Q000187:drug effects / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology*; D009847:Olivary Nucleus / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D009924:Organ Culture Techniques; D018408:Patch-Clamp Techniques; D010446:Peptide Fragments / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism / Q000494:pharmacology; D011494:Protein Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D013873:Thionucleotides / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D010446:Peptide Fragments; D010455:Peptides; D013873:Thionucleotides; C085903:autocamtide-2; C072093:protein kinase C (19-36); C016957:adenosine-3',5'-cyclic phosphorothioate; C063302:KN 62; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000242:Cyclic AMP; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases