title: Effects of environmental enrichment on anxiety responses, spatial memory and cytochrome c oxidase activity in adult rats.
abstract: We have studied the effect of an environmental enrichment (EE) protocol in adult Wistar rats on the activity in the elevated zero-maze (EZM), performance in the radial-arm water maze (RAWM) and we have also examined the changes in the neuronal metabolic activity of several brain regions related to anxiety response and spatial memory through cytochrome c oxidase histochemistry (COx). Our EE protocol had anxiolytic effect in the EZM; the animals spent more time and made more entries into the open quadrants, they had lower latency to enter into the open quadrant and lower levels of defecation. Also, the EE group showed fewer working memory and reference memory errors, as well as lesser distance travelled in the first day of the spatial training. In relation to the neuronal metabolic activity, EE reduced the COx activity in brain regions related to anxiety response, such as the infralimbic cortex, the paraventricular thalamic and hypothalamic nucleus, the basolateral amygdala, and the ventral hippocampus. Interestingly, there were no significant differences between groups in the dorsal hippocampus, more related to spatial cognition. These results suggest a beneficial effect of EE on spatial memory as a result of reducing anxiety levels and the COx activity in brain regions involved in anxiety response. We also found a differential pattern of activation inside the hippocampus, suggesting that the dorsal hippocampus has a preferential involvement in spatial learning and memory, whereas the ventral hippocampus has a role in anxiety response.
authors.affiliation: Laboratorio de Neurociencias, Departamento de Psicología, Universidad de Oviedo, Plaza Feijoo s/n, 33003 Oviedo, Spain. Electronic address: uo179677@uniovi.es.
authors.forename: P
authors.initials: P
authors.lastname: Sampedro-Piquero
authors.forename: C
authors.initials: C
authors.lastname: Zancada-Menendez
authors.forename: A
authors.initials: A
authors.lastname: Begega
authors.forename: S
authors.initials: S
authors.lastname: Rubio
authors.forename: J L
authors.initials: JL
authors.lastname: Arias
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001007:Anxiety / Q000201:enzymology / Q000473:pathology / Q000503:physiopathology; D004195:Disease Models, Animal; D003576:Electron Transport Complex IV / Q000378:metabolism*; D004777:Environment; D008297:Male; D018782:Maze Learning / Q000502:physiology; D008568:Memory / Q000502:physiology*; D017397:Prefrontal Cortex / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013028:Space Perception / Q000502:physiology*; D013223:Statistics as Topic; D013997:Time Factors
chemical_list: D003576:Electron Transport Complex IV
keywords: 4-RAWM; ANOVA of repeated measures; Acb; BNST; BlA; CO; COx; CeA; Cg; Cytochrome c oxidase activity; EE; EE+SPL; EPM; EZM; Elevated zero-maze; Environmental enrichment; GC; HPA; IL; LTP; MANOVA; MO; OD; PL; PVNh; PVNt; RM ANOVA; Radial-arm water maze; SPL; TbE; Wistar rat; accumbens nucleus; basolateral amygdala; bed nucleus stria terminalis; central amygdala; cingulate cortex; control group; cytochrome c oxidase histochemistry; dCA1 dCA3; dDG; dorsal dentate gyrus; dorsal hippocampal cornu ammonis; elevated plus-maze; elevated zero-maze; environmental enrichment; environmental enrichment group; environmental enrichment+spatial learning group; four-arm radial water maze; glucocorticoids; hypothalamic–pituitary–adrenal axis; infralimbic cortex; long-term potentiation; medial orbital cortex; multivariate analysis of variance; optical density; paraventricular hypothalamic nucleus; paraventricular thalamic nucleus; prelimbic cortex; spatial learning group; time by entries; vCA1 vCA3; vDG; ventral dentate gyrus; ventral hippocampal cornu ammonis