Evidence for involvement of glucocorticoid response in the hippocampal changes in aged molarless SAMP8 mice.

The involvement of glucocorticoid response in the hippocampal changes in aged SAMP8 mice after removal of their upper molar teeth (molarless condition) was examined using biochemical, morphological and behavioral techniques. Molarless mice showed plasma corticosterone levels to be significantly greater than those in molar-intact control mice. Pretreatment with metyrapone, which suppresses the stress-induced rise in plasma corticosterone levels, prevented the molarless condition-induced increase in plasma corticosterone levels, reduction in CA1 pyramidal neuron numbers, and impairment of spatial learning. The results suggest a link between the molarless condition and the glucocorticoid response, which may be involved in spatial learning deficits and hippocampal neuronal death in aged SAMP8 mice.