Impaired memory retention and decreased long-term potentiation in integrin-associated protein-deficient mice.

Previously, we have demonstrated that integrin-associated protein (IAP) mRNA level is approximately fourfold higher in rats showing good retention performance (600 sec) than rats showing poor retention performance (< 80 sec) in an inhibitory avoidance learning paradigm. In the present study, we have used the gene-targeted IAP-deficient mice to further investigate the role of IAP involved in memory formation and hippocampal long-term potentiation (LTP) in vivo. Results revealed that there was a significant impairment in memory retention and a significant reduction in the magnitude of LTP in IAP-deficient mice when compared with the wild-type and heterozygote mice, whereas the wild-type and heterozygote animals did not show marked differences on these measures. Furthermore, the impairment in retention performance of IAP-deficient mice was not due to different sensitivities of these animals to the electric shock. When we examined locomotor activity and rotarod treadmill performance, no differences were observed among these three groups of animals either. Western blot analysis confirmed the lack of IAP protein in IAP-deficient mice, whereas IAP expression was similar in both the wild-type and heterozygote controls. These results together demonstrate that IAP plays an important role in the process of memory formation and synaptic plasticity in mice.