Learning Deficits after Experimental Subarachnoid Hemorrhage (SAH)

Survivors of subarachnoid hemorrhage (SAH) often have learning and memory deficits. This study tested the hypothesis that SAH in rats is associated with similar deficits and that they are due to neuronal injury in the hippocampus. SAH was induced in rats. Behaviour was investigated in the Morris water maze and brain injury by microscopy. Rats with SAH had deficits in spatial learning and working memory and had significantly more fluoro-Jade- and TUNEL-positive neurons in the hippocampus, cerebral cortex and cerebellum. Microthromboemboli in microvessels were more frequent in brains of rats with SAH and deficits there was vasospasm of the anterior and middle cerebral arteries. The amount of cell death in the hippocampus did not appear to be sufficient to cause the observed in the Morris water maze. This suggests that other factors such as dysfunction of neurotransmission or other pathology in hippocampal pathways might contribute to the impairment.MAS