Superoxide dismutase and hippocampal function: age and isozyme matter.

Superoxide dismutases (SODs) are the major antioxidant enzymes that inactivate superoxide and thereby control oxidative stress as well as redox signaling. Transgenic mice overexpressing different isozymes of SOD have been used to study the effect of SOD overexpression on hippocampal synaptic plasticity and hippocampus-dependent learning and memory. Studies with transgenic and wild-type animals of different ages show that the function of SOD overexpression changes across the life span of an animal, and comparisons between animals that overexpress different SOD isozymes suggest that the functional value of overexpression as well as the mechanisms through which the respective functional values are effected vary depending on isozyme. The work discussed in this review has important implications for the use of antioxidant treatments and for our understanding of the role of superoxide in physiological and pathological processes.