title: The effects of bilateral vestibular loss on hippocampal volume, neuronal number, and cell proliferation in rats.
abstract: 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. More recently, patients who had recovered from unilateral vestibular neuritis have been reported to exhibit a significant atrophy of the left posterior hippocampus. Therefore, we investigated whether bilateral vestibular deafferentation (BVD) would result in a decrease in neuronal number or volume in the rat hippocampus, using stereological methods. At 16 months post-BVD, we found no significant differences in hippocampal neuronal number or volume compared to sham controls, despite the fact that these animals exhibited severe spatial memory deficits. By contrast, using bromodeoxyuridine (BrdU) as a marker of cell proliferation, we found that the number of BrdU-labeled cells significantly increased in the dentate gyrus of the hippocampus between 48 h and 1 week following BVD. Although a substantial proportion of these cells survived for up to 1 month, the survival rate was significantly lower in BVD animals when compared with that in sham animals. These results suggest a dissociation between the effects of BVD on spatial memory and hippocampal structure in rats and humans, which cannot be explained by an injury-induced increase in cell proliferation.
authors.affiliation: Department of Pharmacology and Toxicology, School of Medical Sciences, University of Otago Medical School Dunedin, New Zealand.
authors.forename: Yiwen
authors.initials: Y
authors.lastname: Zheng
authors.forename: Sangeeta
authors.initials: S
authors.lastname: Balabhadrapatruni
authors.forename: Jean Ha
authors.initials: JH
authors.lastname: Baek
authors.forename: Phoebe
authors.initials: P
authors.lastname: Chung
authors.forename: Catherine
authors.initials: C
authors.lastname: Gliddon
authors.forename: Ming
authors.initials: M
authors.lastname: Zhang
authors.forename: Cynthia L
authors.initials: CL
authors.lastname: Darlington
authors.forename: Ruth
authors.initials: R
authors.lastname: Napper
authors.forename: Michael
authors.initials: M
authors.lastname: Strupp
authors.forename: Thomas
authors.initials: T
authors.lastname: Brandt
authors.forename: Paul F
authors.initials: PF
authors.lastname: Smith