title: Extracellular superoxide dismutase overexpression protects against aging-induced cognitive impairment in mice.
abstract: Extracellular superoxide dismutase (EC-SOD) controls the availability of extracellular superoxide and appears to play a role in controlling oxidative stress and intercellular signaling. Whether EC-SOD overexpression would help or hinder neurobehavioral function appears to depend on the age of the individual. In young adult mice, we have found that EC-SOD overexpression can interfere with learning on the radial-arm maze, possibly by reducing control over nitric oxide neurotransmission. In aged mice, we found, in the current study, that EC-SOD overexpression greatly improves learning on the radial-arm maze. Control (N = 17) and EC-SOD overexpressing mice (N = 13) acquired the 8-arm radial maze over 21 sessions of training. The EC-SOD overexpressing mice had significantly better choice accuracy than the control mice (p < 0.005). The EC-SOD overexpressing mice averaged 6.34+/-0.22 correct arm entries before an error (entries to repeat) during the acquisition phase, while the control mice averaged 5.18+/-0.22 entries to repeat. EC-SOD genotype did not cause a main effect on response latency. The advantage held by the EC-SOD overexpressing mice persisted during the eight-session post-acquisition phase of testing (p < 0.01). When there was a shift from high to low levels of motivation by reducing the period of food restriction before testing, the EC-SOD overexpression-induced improvement was reduced slightly, but it was still significant compared with the wild-type controls (p < 0.025). Then, after 4 months of no testing, the mice were tested for retention and reacquisition of performance on the radial-arm maze. The EC-SOD overexpressing mice maintained their significantly better choice accuracy (p < 0.05). Enhancement of EC-SOD activity appears to improve learning and memory performance, specifically in aging mice. EC-SOD mimetic treatment during the course of aging may hold promise for aging-induced cognitive impairment.
authors.affiliation: Dept of Psychiatry and Behavioral Sciences, Duke University, Durham, NC 27710, USA. edlevin@duke.edu
authors.forename: Edward D
authors.initials: ED
authors.lastname: Levin
authors.forename: N Channelle
authors.initials: NC
authors.lastname: Christopher
authors.forename: Sohail
authors.initials: S
authors.lastname: Lateef
authors.forename: Belal M
authors.initials: BM
authors.lastname: Elamir
authors.forename: Manisha
authors.initials: M
authors.lastname: Patel
authors.forename: Li-Ping
authors.initials: LP
authors.lastname: Liang
authors.forename: James D
authors.initials: JD
authors.lastname: Crapo
mesh_terms: D000375:Aging / Q000235:genetics*; D000818:Animals; D005110:Extracellular Space / Q000201:enzymology*; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D005838:Genotype; D006801:Humans; D018782:Maze Learning / Q000502:physiology*; D051379:Mice; D008822:Mice, Transgenic; D018384:Oxidative Stress / Q000235:genetics; D012153:Retention, Psychology / Q000502:physiology*; D015398:Signal Transduction / Q000235:genetics; D013482:Superoxide Dismutase / Q000235:genetics*
chemical_list: D013482:Superoxide Dismutase