Behavioral impairments and changes of nitric oxide and inducible nitric oxide synthase in the brains of molarless KM mice.

More studies showed that as a common disorder in senior population, loss of teeth could adversely affect human cognitive function, and nitric oxide (NO) might play an important role in the cognitive function. However, the underlying mechanism has not yet been well-established. The objectives of this study are to evaluate behavior changes of KM mice after loss of molars, and levels of NO and inducible nitric oxide synthase (iNOS) in the brain in molarless condition. It is hypothesized that loss of molars of the mice tested results in the cognitive impairments and that the process is mediated by NO in the brain through the signaling pathways. Morris water maze is used to test the behavioral changes after 8 weeks of the surgery. The changes of NO and iNOS are evaluated by using Griess assay, western blot, and immunohistochemistry method. The results show that 8 weeks after loss of molars, the spatial learning and memory of KM mice impair and the levels of NO and iNOS in mice hippocampus increase. These findings suggest that molar extraction is associated with the behavioral impairment, and that the changes of NO and iNOS in the hippocampus may be involved in the behavioral changes in the molarless condition.