Aquaporin7 expression during perinatal development of mouse brain

Emerging evidence suggests that brain aquaporins (AQPs) play important roles in the dynamic regulation of brain water homeostasis and the production of cerebrospinal fluid (CSF) under normal, as well as pathological, conditions. To date, the spatiotemporal expression patterns of AQP1, 4, and 9 have been elucidated in brain tissues. However, the expression of AQP7, an aquaglyceroporin associated with brain development, has not been shown. In the present study, we examined expression of AQP7 during perinatal and adult brain development in the mouse. Throughout brain development, the immunoreactivity of AQP7 was largely found in the choroid plexus (CP). AQP7 immunoreactivity in ependyma (Ep), pia, and blood vessels (BV) was increased during perinatal to postnatal development. Cells in the different layers of cerebral cortex became a little positive for AQP7 immunoreactivity during postnatal development. Optimized semi-quantitative RT-PCR and Western blot analysis revealed that AQP7 mRNA and protein levels increased during perinatal development of brain. To our knowledge, this is the first report on the pattern of AQP7 expression in brain tissues. These results suggest that AQP7 is an important structural element in the choroid plexus and is possibly involved in the production of CSF during brain development in mice.