Down-regulated expression of aquaporin-4 in the cerebellum after status epilepticus.

Status epilepticus (SE) is a common neurological condition associated with high rates of mortality and permanent brain injury. SE usually leads to neuronal death which may be accompanied by edema, epileptogenesis and learning impairment. Aquaporin-4 (AQP4), is a transmembrane water channel protein in the neuropil of the central nervous system that has an important role in water transport in the brain; AQP4 expression is altered in many pathological conditions such as changes in the blood- brain barrier and/or astrocytic activation, including seizures. AQP4 was shown to be downregulated in the piriform cortex and the hippocampus after SE. Although it is normally expressed at a high level in the cerebellum, little is known about AQP4 levels in the cerebellum following SE. We addressed this in the present study in a mouse model of pilocarpine-induced SE. We found that AQP4 expression was reduced from 3 h to 3 days after SE, with the levels recovering on day 7. Moreover, mice in the acute post-SE stages exhibited impaired motor coordination and learning. These results indicate that cerebellar damage following SE involves changes in AQP4 expression.