Age-related alterations of Apolipoprotein E and interleukin-1beta in the aging brain

With normal aging, the brain undergoes several alterations including reduced neuronal functioning and alterations in glia homeostasis. An increase in inflammatory signaling has also been reported in some studies of the aging brain, with inflammation potentially mediating age-related changes in the brain. Apolipoprotein E (ApoE) is produced in the brain and has been shown to possess anti-inflammatory properties in a variety of paradigms. In the present study, we correlated age-related alterations in ApoE expression with age-related changes in the cytokine interleukin-1 beta (IL-1beta), in the brain of rats of increasing age. No significant alteration in ApoE mRNA was found in any region examined. A significant increase in IL-1beta mRNA with age was observed only in the cortex. Neither ApoE nor IL-1beta protein expression was significantly altered with age in the brain. A significant linear correlation between ApoE and IL-1beta mRNA was found in the cortex but not in the striatum or hippocampus. No correlation was found between ApoE and IL-1beta protein in any region examined. Taken together, these studies demonstrate that ApoE expression is not altered during normal brain aging, but suggest that there may be a relationship between ApoE and IL-1beta transcription in the cerebral cortex.