Aging increases UT-B urea transporter protein abundance in brains of male mice.

Abstract

Facilitative UT-B urea transporters in the brain play an important role in regulating levels of urea in various cell types, including astrocytes. Numerous studies have reported increased UT-B RNA expression with aging and in neurological disorders, such as Alzheimer's Disease. However, much less is known about the effects of these conditions on UT-B transporter protein abundance. This current study compared the levels of UT-B RNA and protein in young and aged male C57BL/6 mice. Endpoint RT-PCR experiments showed UT-B RNA expression increased in both aged cortex and aged hippocampus. Importantly, these changes were coupled with an increase in protein abundance, as western blotting revealed that 30-35 kDa UT-B1 protein was significantly increased in aged mouse brain tissues compared with tissue from young animals. An increased UT-B1 protein abundance was observed in the hippocampus, cerebellum, frontal cortex, and occipital cortex. In contrast, no such changes were observed in the abundance of MCT1 short-chain fatty acid transporters in these aged tissues. These data therefore confirmed that specific increases in UT-B1 protein abundance occur in multiple regions of the aged male mouse brain. Further studies are now needed to determine cell-specific changes and the functional consequence of increased UT-B1 protein in aged brain tissues.