title: Spatial memory in the Morris water maze and activation of cyclic AMP response element-binding (CREB) protein within the mouse hippocampus.
abstract: We investigated the spatio-temporal dynamics of learning-induced cAMP response element-binding protein activation/phosphorylation (pCREB) in mice trained in a spatial reference memory task in the water maze. Using immunohistochemistry, we examined pCREB immunoreactivity (pCREB-ir) in hippocampal CA1 and CA3 and related brain structures. During the course of spatial learning over Days 1-9, pCREB-ir progressively increased in hippocampal neurons whereas its level in the dorsal striatum decreased. No significant changes were observed in the prelimbic cortex and lateral amygdala. Mice killed at various time points after the last training session demonstrated two waves of pCREB-ir in CA1 and an early transient CREB phosphorylation in area CA3, lateral amygdala, and prelimbic cortex. We show that CREB phosphorylation and downstream gene Zif268 activation remained sustained in CA1 and CA3 for at least 24 h after extended training (Days 8-9) but not during early training (Day 3). The present results indicate that the strong CA1 CREB phosphorylation observed immediately after training was not related strictly to learning or to memory. In contrast, at 15 min after training, the changes in CA1 CREB phosphorylation state were specifically related to individual learning capability. We suggest that hippocampal-learning specificity of CREB is reflected best by duration, rather than magnitude, of CREB phosphorylation.
authors.affiliation: CNRS UMR 5228, Centre de Neurosciences Intégratives et Cognitives, 33405 Talence, France.
authors.forename: Yves
authors.initials: Y
authors.lastname: Porte
authors.forename: Marie Christine
authors.initials: MC
authors.lastname: Buhot
authors.forename: Nicole E
authors.initials: NE
authors.lastname: Mons
mesh_terms: D000818:Animals; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism*; D051766:Early Growth Response Protein 1 / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology*; D006624:Hippocampus / Q000378:metabolism*; D016014:Linear Models; D008297:Male; D018782:Maze Learning / Q000502:physiology*; D008568:Memory / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D010766:Phosphorylation; D013028:Space Perception / Q000502:physiology*; D013997:Time Factors
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D051766:Early Growth Response Protein 1; C486109:Egr1 protein, mouse