AQP-4 expression was higher in the sixth than in the first month after inoculation (P = 0.016) and also occurred in animals that received antigen inoculation but did not develop hydrocephalus, suggesting that AQP-4 may constitute an alternative route of cerebrospinal fluid absorption under inflammatory conditions.
In a state of aquaporin-4 dysfunction such as in neuromyelitis optica, altered cerebrospinal fluid resorption could lead to acute hydrocephalus by a nonobstructive mechanism.
Significant increases in aquaporin-4 expression that occur over the course of animal aging, together with a reduced cerebrospinal fluid outflow rate and ventricular compliance, contribute to produce more severe hydrocephalus related to hypoxic events in aged mice, with a notable impairment in cognitive function.
With advancing hydrocephalus, expression of AQPs 1 and 4 increased at the brain-CSF interfaces; AQP1 was localized to the endothelium of cortical capillaries with increased AQP4 expression in surrounding astrocytes end feet.