title: Induction of hippocampal LTD requires nitric-oxide-stimulated PKG activity and Ca2+ release from cyclic ADP-ribose-sensitive stores.
abstract: Long-term depression (LTD) of synaptic transmission can be induced by several mechanisms, one thought to involve Ca2+-dependent activation of postsynaptic nitric oxide (NO) synthase and subsequent diffusion of NO to the presynaptic terminal. We used the stable NO donor S-nitroso-N-acetylpenicillamine (SNAP) to study the NO-dependent form of LTD at Schaffer collateral-CA1 synapses in vitro. SNAP (100 microM) enhanced the induction of LTD via a cascade that was blocked by the N-methyl-D-aspartate receptor antagonist D-2-amino-5-phosphonopentanoic acid (50 microM), NO guanylyl cyclase inhibitor 1H-[1,2,4] oxadiazolo [4,3-a] quinoxalin-1-one (10 microM), and the PKG inhibitor KT5823 (1 microM). We further show that LTD induced by low-frequency stimulation in the absence of SNAP also is blocked by KT5823 or Rp-8-(4-chlorophenylthio)-guanosine 3',5'-cyclic monophosphorothioate (10 microM), cyclic guanosine 3',5' monophosphate-dependent protein kinase (PKG) inhibitors with different mechanisms of action. Furthermore SNAP-facilitated LTD was blocked when release from intracellular calcium stores was inhibited by ryanodine (10 microM). Finally, two cell-permeant antagonists of the cyclic ADP-ribose binding site on ryanodine receptors also were able to block the induction of LTD. These results support a cascade for induction of homosynaptic, NO-dependent LTD involving activation of guanylyl cyclase, production of guanosine 3',5' cyclic monophosphate and subsequent PKG activation. This process has an additional requirement for release of Ca2+ from ryanodine-sensitive stores, perhaps dependent on the second-messenger cyclic ADP ribose.
authors.affiliation: Departments of Neuroscience and Neurology, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
authors.forename: M
authors.initials: M
authors.lastname: Reyes-Harde
authors.forename: B V
authors.initials: BV
authors.lastname: Potter
authors.forename: A
authors.initials: A
authors.lastname: Galione
authors.forename: P K
authors.initials: PK
authors.lastname: Stanton
mesh_terms: D000246:Adenosine Diphosphate Ribose / Q000031:analogs & derivatives* / Q000502:physiology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D036563:Cyclic ADP-Ribose; D017869:Cyclic GMP-Dependent Protein Kinases; D004558:Electric Stimulation; D005260:Female; D006162:Guanylate Cyclase / Q000378:metabolism; D006624:Hippocampus / Q000502:physiology*; D017774:Long-Term Potentiation / Q000502:physiology*; D008297:Male; D009569:Nitric Oxide / Q000502:physiology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D010396:Penicillamine / Q000031:analogs & derivatives / Q000494:pharmacology; D011494:Protein Kinases / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology; D012433:Ryanodine / Q000494:pharmacology; D019837:Ryanodine Receptor Calcium Release Channel / Q000502:physiology; D026423:S-Nitroso-N-Acetylpenicillamine; D013569:Synapses / Q000502:physiology
chemical_list: D020030:Nitric Oxide Donors; D016194:Receptors, N-Methyl-D-Aspartate; D019837:Ryanodine Receptor Calcium Release Channel; D036563:Cyclic ADP-Ribose; D012433:Ryanodine; D000246:Adenosine Diphosphate Ribose; D009569:Nitric Oxide; D026423:S-Nitroso-N-Acetylpenicillamine; D011494:Protein Kinases; D017869:Cyclic GMP-Dependent Protein Kinases; D006162:Guanylate Cyclase; D010396:Penicillamine; D002118:Calcium