title: Beta-adrenergic receptors link NO/sGC/PKG signaling to BDNF expression during the consolidation of object recognition long-term memory.
abstract: The nitric oxide (NO)/soluble guanylyl cyclase (sGC)/protein kinase G (PKG) pathway is important for memory processing, but the identity of its downstream effectors as well as its actual participation in the consolidation of nonaversive declarative long-term memory (LTM) remain unknown. Here, we show that training rats in an object recognition (OR) learning task rapidly increased nitrites/nitrates (NOx) content in the CA1 region of the dorsal hippocampus while posttraining intra-CA1 microinfusion of the neuronal NO synthase (nNOS) inhibitor L-NN hindered OR LTM retention without affecting memory retrieval or other behavioral variables. The amnesic effect of L-NN was not state dependent, was mimicked by the sGC inhibitor LY83583 and the PKG inhibitor KT-5823, and reversed by coinfusion of the NO donor S-nitroso-N-acetylpenicillamine (SNAP) and the PKG activator 8-bromoguanosine 3',5'-cyclic monophosphate (8Br-cGMP). SNAP did not affect the amnesic effect of LY83583 and KT-5823. Conversely, 8Br-cGMP overturned the amnesia induced by LY83583 but not that caused by KT-5823. Intra-CA1 infusion of the beta-adrenergic receptor blocker timolol right after training hindered OR LTM and, although coadministration of noradrenaline reversed the amnesia caused by L-NN, LY83583, and KT5823, the amnesic effect of timolol was unaffected by coinfusion of 8Br-cGMP or SNAP, indicating that hippocampal beta-adrenergic receptors act downstream NO/sGC/PKG signaling. We also found that posttraining intra-CA1 infusion of function-blocking anti-brain-derived neurotrophic factor (BDNF) antibodies hampered OR LTM retention, whereas OR training increased CA1 BDNF levels in a nNOS- and beta-adrenergic receptor-dependent manner. Taken together, our results demonstrate that NO/sGC/PKG signaling in the hippocampus is essential for OR memory consolidation and suggest that beta-adrenergic receptors link the activation of this pathway to BDNF expression during the consolidation of declarative memories.
authors.affiliation: Centro de Memória, Instituto do Cérebro, Pontifícia Universidade Católica do Rio Grande do Sul and Instituto Nacional de Neurociência Translacional, Conselho Nacional de Desenvolvimento Científico e Tecnológico, Porto Alegre, RS, Brasil.
authors.forename: Cristiane R
authors.initials: CR
authors.lastname: Furini
authors.forename: Janine I
authors.initials: JI
authors.lastname: Rossato
authors.forename: Lucas L
authors.initials: LL
authors.lastname: Bitencourt
authors.forename: Jorge H
authors.initials: JH
authors.lastname: Medina
authors.forename: Iván
authors.initials: I
authors.lastname: Izquierdo
authors.forename: Martín
authors.initials: M
authors.lastname: Cammarota
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D001522:Behavior, Animal; D019208:Brain-Derived Neurotrophic Factor / Q000276:immunology / Q000378:metabolism*; D017869:Cyclic GMP-Dependent Protein Kinases / Q000378:metabolism; D004193:Discrimination Learning / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D006162:Guanylate Cyclase / Q000378:metabolism; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011943:Receptors, Adrenergic, beta / Q000502:physiology*; D021641:Recognition, Psychology / Q000187:drug effects / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors; D013999:Timolol / Q000494:pharmacology
chemical_list: D000319:Adrenergic beta-Antagonists; D000906:Antibodies; D019208:Brain-Derived Neurotrophic Factor; D004791:Enzyme Inhibitors; D011943:Receptors, Adrenergic, beta; D009569:Nitric Oxide; D013999:Timolol; D017869:Cyclic GMP-Dependent Protein Kinases; D006162:Guanylate Cyclase