A role for calcium/calmodulin-dependent protein kinase in mediating synaptic modulation by a neuropeptide.
The crayfish neuropeptide DRNFLRFamide (DF2) has previously been shown to increase the amplitude of excitatory post-synaptic potentials (EPSPs) in crayfish muscles by enhancing transmitter release from synaptic terminals [18]. This effect involves at least two types of kinase enzyme: one or more kinases which mediate the initial rise in EPSP amplitude, and protein kinase C (PKC) which prolongs the elevation in EPSP amplitude for several minutes [6,7]. The present investigation was aimed at identifying kinases that participate in the initial response. KN-62, an inhibitor of Ca2+/calmodulin-dependent protein kinase, delayed the rise in EPSP amplitude induced by DF2. The maximal response to the peptide occurred in about 40 min when KN-62 was present and in 15 min when the inhibitor was absent. KN-62 did not significantly alter EPSP amplitude by itself. KN-04, a structural analog of KN-62 which does not block Ca2+/CaM kinase activity, did not alter EPSP amplitude or the response to the neuropeptide. These data strongly suggest that Ca2+/CaM kinase participates in the initial increase in transmitter release.
Noronha
K F
KF
Department of Biological Sciences, Brock University, St. Catharines, Ont., Canada.
Mercier
A J
AJ
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000031:analogs & derivatives*; D000818:Animals; D003400:Astacoidea / Q000502:physiology*; D054677:Cyclic Nucleotide Phosphodiesterases, Type 1; D005071:Evoked Potentials / Q000187:drug effects; D019835:FMRFamide; D007546:Isoquinolines / Q000494:pharmacology; D009479:Neuropeptides / Q000494:pharmacology*; D010727:Phosphoric Diester Hydrolases / Q000502:physiology*; D010879:Piperazines / Q000494:pharmacology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors
D007546:Isoquinolines; D009479:Neuropeptides; D010879:Piperazines; C088642:neuropeptide DF2; C063302:KN 62; D019835:FMRFamide; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D010727:Phosphoric Diester Hydrolases; D054677:Cyclic Nucleotide Phosphodiesterases, Type 1