Hippocampal noradrenergic activation is necessary for object recognition memory consolidation and can promote BDNF increase and memory persistence

• Published in: Neurobiology of learning and memory Vol. 127; pp. 84 - 92
• Main Authors: Mello-Carpes, Pâmela B., da Silva de Vargas, Liane, Gayer, Mateus Cristofari, Roehrs, Rafael, Izquierdo, Ivan
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.01.2016; Elsevier BV
• Subjects: Adrenergic beta-Antagonists - administration & dosage; Animals; BDNF; Brain; Brain-derived neurotrophic factor; Brain-Derived Neurotrophic Factor - metabolism; Excitatory Amino Acid Agonists - administration & dosage; Exploratory Behavior - drug effects; Exploratory Behavior - physiology; GABA-A Receptor Agonists - administration & dosage; Hippocampus - drug effects; Hippocampus - metabolism; Hippocampus - physiology; Locus Coeruleus - drug effects; Locus Coeruleus - physiology; Male; Memory; Memory Consolidation - drug effects; Memory Consolidation - physiology; Memory persistence; Muscimol - administration & dosage; N-Methylaspartate - administration & dosage; Neurobiology; Norepinephrine; Norepinephrine - administration & dosage; Norepinephrine - physiology; Nucleus of the Solitary Tract; Rats, Wistar; Recognition (Psychology) - drug effects; Recognition (Psychology) - physiology; Solitary Nucleus - drug effects; Solitary Nucleus - physiology; Timolol - administration & dosage; Memory persistence; Norepinephrine; BDNF; Nucleus of the Solitary Tract
• ISSN: 1074-7427; 1095-9564
• DOI: 10.1016/j.nlm.2015.11.014

•NE injection on hippocampus promotes OR memory persistence.•NMDA infusion in LC shares the effect of NE into CA1.•OR training consolidation is attended by an increase of hippocampal NE levels.•OR training consolidation is attended by an increase of hippocampal BDNF.•NTS–PGi–LC pathway activation mediates the increase of hippocampal NE and BDNF. Previously we showed that activation of the Nucleus of the Solitary Tract (NTS)–Nucleus Paragigantocellularis (PGi)–Locus coeruleus (LC) pathway, which theoretically culminates with norepinephrine (NE) release in dorsal hippocampus (CA1 region) and basolateral amygdala (BLA) is necessary for the consolidation of object recognition (OR) memory. Here we show that, while the microinjection of the beta-noradrenergic receptor blocker timolol into CA1 impairs OR memory consolidation, the microinjection of norepinephrine (NE) promotes the persistence of this type of memory. Further, we show that OR consolidation is attended by an increase of norepinephrine (NE) levels and of the expression of brain derived neurotrophic factor (BDNF) in hippocampus, which are impaired by inactivation of the NTS–PGi–LC pathway by the infusion of muscimol into the NTS.