title: cAMP-dependent long-term potentiation of nitric oxide release from cerebellar parallel fibers in rats.
abstract: Nitric Oxide (NO) is released from parallel fibers (PFs) after PF stimulation. NO-cGMP signaling is essential for long-term depression (LTD) in cerebellar PF-Purkinje cell synapses, which also exhibit presynaptic long-term potentiation (LTP) after tetanic PF stimulation. This LTP is dependent on cAMP but not NO-cGMP signaling. In this study, we analyzed long-term changes of NO release from PFs in rat cerebellar slices using electrochemical NO probes. Repetitive PF stimulation at 10 Hz for 2 sec elicited a transient increase in NO concentration (2.2 +/- 0.1 nM; mean +/- SEM; n = 116). This NO release exhibited long-term potentiation (LTPNO) by 36 +/- 3% (n = 15) after tetanic PF stimulation. Induction of LTPNO was not affected by Glu receptor antagonists. NO release from PFs was also potentiated by L-Arg (ARG) (100 microM), forskolin (50 microM), and 8-bromo-cAMP (Br-cAMP) (1 mM) but not by 1,9-dideoxyforskolin (50 microM), a biologically inactive analog of forskolin. The potentiation induced by forskolin was significantly suppressed by H89 (10 microM), a blocker of cAMP-dependent protein kinase. The potentiation induced by forskolin, but not that induced by Arg, interfered with LTPNO. H89 (10 microM) and KT5720 (1 microM), another blocker of cAMP-dependent protein kinase, but not KT5823 (300 nM), a blocker of cGMP-dependent protein kinase, significantly suppressed LTPNO. These data indicate that neural NO release is under activity-dependent control, just as synaptic transmitter release is. LTPNO might play a role in cross talk between presynaptic and postsynaptic plasticity by facilitating NO-cGMP-dependent postsynaptic LTD after induction of cAMP-dependent presynaptic LTP and LTPNO.
authors.affiliation: Department of Neurophysiology, Brain Research Institute, School of Medicine, Niigata University, Niigata 951-8585, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Kimura
authors.forename: S
authors.initials: S
authors.lastname: Uchiyama
authors.forename: H E
authors.initials: HE
authors.lastname: Takahashi
authors.forename: K
authors.initials: K
authors.lastname: Shibuki
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D001120:Arginine / Q000494:pharmacology; D002531:Cerebellum / Q000378:metabolism*; D005576:Colforsin / Q000031:analogs & derivatives / Q000494:pharmacology; D000242:Cyclic AMP / Q000502:physiology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D007546:Isoquinolines / Q000494:pharmacology; D017774:Long-Term Potentiation / Q000187:drug effects; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013449:Sulfonamides
chemical_list: D004791:Enzyme Inhibitors; D007546:Isoquinolines; D013449:Sulfonamides; D005576:Colforsin; D015124:8-Bromo Cyclic Adenosine Monophosphate; D009569:Nitric Oxide; D001120:Arginine; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide