Low-level blast raises intracranial pressure and impairs cognitive function in rats: prophylaxis with processed cereal feed.

There is increasing evidence that even low levels of blast cause brain injury, but little is known about their thresholds and mechanisms. Exposure of rats to 10-60 kPa blasts elevate intracranial pressure (ICP) in a dose-dependent manner and impair cognitive function. We have evaluated a prophylactic measure against these brain injuries in a rat animal model, consisting of feeding them processed cereal. This type of feed is known to ameliorate disturbances in secretion of body fluids and to have anti-inflammatory effects. In humans, intake of processed cereals is effective against intestinal diarrhea and also reduces the symptoms of Ménière's disease. Rats were given either standard laboratory feed or processed cereal feed for 2 weeks before exposure to blast in a shock tube. The ICP was monitored at different time points up to 1 week after exposure to a 60-kPa blast, and for up to 24 h after exposure to a 30-kPa blast. Maximal ICP elevation was reached at 10 h in both groups. In the group of rats on standard feed exposed to 60 kPa, an ICP increase of 145% was noted at 10 h, and the corresponding increase in the rats fed processed cereal feed was only 50%. In rats exposed to a 30-kPa blast, those fed standard feed and processed cereal feed demonstrated increases of ICP of 80% and 40%, respectively. Cognitive function as measured by the Morris water maze was assessed in other groups of rats at 2 days after exposure to 10- or 30-kPa blasts. Their performance was significantly impaired at both exposure levels in rats on standard feed, but no functional impairment was seen in rats fed processed cereal feed.