Basal dendritic length is reduced in the rat hippocampus following bilateral vestibular deafferentation

Some previous studies in humans have shown that bilateral loss of vestibular function is associated with a significant bilateral atrophy of the hippocampus, which correlated with the patients' spatial memory deficits. By contrast, studies in rats have failed to detect any changes in hippocampal volume following bilateral vestibular loss. Therefore, in this study we investigated whether bilateral vestibular deafferentation (BVD) might result in more subtle morphological changes in the rat hippocampus, involving alterations in dendritic intersections, using Golgi staining and Sholl analysis. We found that at 1month following BVD, there was a significant decrease in basal (P⩽0.0001) but not apical dendritic intersections in the CA1 region of the hippocampus compared to sham-operated animals and anaesthetic controls. However, dendritic branching was not significantly affected. These results suggest that the rat hippocampus does undergo subtle morphological changes following bilateral vestibular loss, and that they may be in the form of alterations in dendritic structure.