title: Time-dependent enhancement of inhibitory avoidance retention and MAPK activation by post-training infusion of nerve growth factor into CA1 region of hippocampus of adult rats.
abstract: Several studies have demonstrated that chronic intracerebroventricular nerve growth factor (NGF) infusion has a beneficial effect on cognitive performance of lesioned as well as old and developing animals. Here we investigate: (i) the effect of post-training infusion of NGF into the CA1 region of hippocampus on inhibitory avoidance (IA) retention in rats; (ii) the extension of the effect, in time and space, of NGF infusion into CA1 on the activity of mitogen-activated protein kinase (MAPK, syn: ERK1/2, p42/p44 MAPK). NGF was bilaterally injected into the CA1 regions of the dorsal hippocampus (0.05, 0.5 or 5.0 ng diluted in 0.5 microL of saline per side ) at 0, 120 or 360 min after IA training in rats. Retention testing was carried out 24 h after training. The injection of 5.0 and 0.5, but not 0.05, ng per side of NGF at 0 and 120 min after IA training enhanced IA retention. The highest dose used was ineffective when injected 360 min after training. The infusion of 0. 5 microL of NGF (5.0 ng) induced a significant enhancement of MAPK activity in hippocampal microslices; this enhancement was restricted to a volume with 0.8 mm radius at 30 min after injection. The MAPK activation was still seen 180 min after NGF infusion, although this value showed only a tendency. In conclusion, localized infusion of NGF into the CA1 region enhanced MAPK activity, restricted in time and space, and enhanced IA retention in a time- and dose-dependent manner.
authors.affiliation: Centro de Memória and Laboratório de Plasticidade Neuroglial, Departamento de Bioquímica, ICBS, UFRGS, Ramiro Barcellos 2600, 90035-003, Brazil. rogerwalz@hotmail.com
authors.forename: R
authors.initials: R
authors.lastname: Walz
authors.forename: G
authors.initials: G
authors.lastname: Lenz
authors.forename: R
authors.initials: R
authors.lastname: Roesler
authors.forename: M M
authors.initials: MM
authors.lastname: Vianna
authors.forename: V
authors.initials: V
authors.lastname: Martins
authors.forename: R
authors.initials: R
authors.lastname: Brentani
authors.forename: R
authors.initials: R
authors.lastname: Rodnight
authors.forename: I
authors.initials: I
authors.lastname: Izquierdo
mesh_terms: D000367:Age Factors; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects* / Q000502:physiology*; D003071:Cognition / Q000502:physiology; D006624:Hippocampus / Q000187:drug effects / Q000201:enzymology*; D020935:MAP Kinase Signaling System / Q000502:physiology*; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D020932:Nerve Growth Factor / Q000494:pharmacology*; D009924:Organ Culture Techniques; D051381:Rats; D017208:Rats, Wistar
chemical_list: D020932:Nerve Growth Factor; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases