Observation of the morphology and calcium content of vestibular otoconia in rats after simulated weightlessness

Zhang, Jiangping; Peng, Zhenhui; Yang, Miaoli; Zhang, Xianghong; Wei, Jian; Xu, Min; Zheng, Qing Yin

doi:10.1080/00016480510037915

Cited by 12 publications

(9 citation statements)

References 8 publications

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“…To date, every rat or guinea pig study that has examined corticosterone or cortisol levels (respectively) following unilateral or BVD has found no significant difference compared to sham controls up 5 months post-op. (Gliddon et al, 2003; Lindsay et al, 2005; Zhang et al, 2005; Russell et al, 2006; Zheng et al, 2008). It is conceivable that BVD causes a long-term increase in glucocorticoids only in humans, as a result of the psychosocial impact of living without a balance system.…”

Section: Discussionmentioning

confidence: 99%

“…We considered that these smaller sample sizes were justified in this particular case, based on the precision of stereological analysis, which involves minimal measurement error and therefore reduces variation (Gundersen and Jensen, 1987; West and Gundersen, 1990; Zhang et al, 2005). Although averages across animals were used in the Section “Statistical Analyses” (see below), error in the estimates for individual animals contributes to the overall variation around the group means, and objective and precise counting procedures can minimize this error.…”

Section: Methodsmentioning

confidence: 99%

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The Effects of Bilateral Vestibular Loss on Hippocampal Volume, Neuronal Number, and Cell Proliferation in Rats

Zheng¹,

Balabhadrapatruni²,

Baek³

et al. 2012

Front. Neur.

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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.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

The Effects of Bilateral Vestibular Loss on Hippocampal Volume, Neuronal Number, and Cell Proliferation in Rats

Zheng¹,

Balabhadrapatruni²,

Baek³

et al. 2012

Front. Neur.

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“…An alternative, however, is that responses are dampened after repeated exposure because the high magnetic fields persistently alter or damage the peripheral vestibular apparatus. Prolonged or intense stimuli, such as chronic weightlessness [50, 51], rotation [52], changes in atmospheric pressure [53], or even a percussive auditory stimulus [54] can cause long-lasting damage to the semicircular canals or otolith organs. In Experiment 3 we observed a long-term decrement (after 36 days) in the induction of locomotor circling, although not in CTA acquisition.…”

Section: Discussionmentioning

confidence: 99%

Repeated exposure attenuates the behavioral response of rats to static high magnetic fields

Houpt¹,

Cassell²,

Hood³

et al. 2010

Physiology & Behavior

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Exposure of rats to high strength static magnetic fields of 7 T or above has behavioral effects such as the induction of locomotor circling, the suppression of rearing, and the acquisition of conditioned taste aversion (CTA). To determine if habituation occurs across magnetic field exposures, rats were pre-exposed two times to a 14 T static magnetic field for 30 min on two consecutive days; on the third day, rats were given access to a novel 0.125% saccharin prior to a third 30-min exposure to the 14 T magnetic field. Compared to sham-exposed rats, pre-exposed rats showed less locomotor circling and an attenuated CTA. Rearing was suppressed in all magnet-exposed groups regardless of pre-exposure, suggesting that the suppression of rearing is more sensitive than other behavioral responses to magnet exposure. Habituation was also observed when rats under went pre-exposures at 2-3 hour intervals on a single day. Components of the habituation were also long lasting; a diminished circling response was observed when rats were exposed to magnetic field 36 days after 2 pre-exposures. To control for possible effects of unconditioned stimulus pre-exposure, rats were also tested in a similar experimental design with two injections of LiCl prior to the pairing of saccharin with a third injection of LiCl. Pre-exposure to LiCl did not attenuate the LiCl-induced CTA, suggesting that 2 pre-exposures to an unconditioned stimulus are not sufficient to explain the habituation to magnet exposure. Because the effects of magnetic field exposure are dependent on an intact vestibular apparatus, and because the vestibular system can habituate to many forms of perturbation, habituation to magnetic field exposure is consistent with mediation of magnetic field effects by the vestibular system.

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“…By contrast, Lindsay et al (2005) and Zhang et al (2005) assayed serum corticosterone at 10 h and 2 weeks post UVD in three groups of rats either having undergone surgical UVD, sham surgery, or no surgery (anesthetic control), and found no significant difference in serum corticosterone between groups. Lindsay et al (2005) additionally assessed serum corticosterone at 58 h and found that all groups had a significant decrease in corticosterone, while Zhang et al (2005) found that the 10-h serum corticosterone was higher in all groups when compared with the 2-week time-point (Lindsay et al, 2005; Zhang et al, 2005).…”

Section: Stress and Vestibular Compensation In Animal Studiesmentioning

confidence: 96%

“…Lindsay et al (2005) additionally assessed serum corticosterone at 58 h and found that all groups had a significant decrease in corticosterone, while Zhang et al (2005) found that the 10-h serum corticosterone was higher in all groups when compared with the 2-week time-point (Lindsay et al, 2005; Zhang et al, 2005). …”

Section: Stress and Vestibular Compensation In Animal Studiesmentioning

confidence: 99%

Interactions between Stress and Vestibular Compensation – A Review

Saman¹,

Bamiou²,

Gleeson³

et al. 2012

Front. Neur.

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Elevated levels of stress and anxiety often accompany vestibular dysfunction, while conversely complaints of dizziness and loss of balance are common in patients with panic and other anxiety disorders. The interactions between stress and vestibular function have been investigated both in animal models and in clinical studies. Evidence from animal studies indicates that vestibular symptoms are effective in activating the stress axis, and that the acute stress response is important in promoting compensatory synaptic and neuronal plasticity in the vestibular system and cerebellum. The role of stress in human vestibular disorders is complex, and definitive evidence is lacking. This article reviews the evidence from animal and clinical studies with a focus on the effects of stress on the central vestibular pathways and their role in the pathogenesis and management of human vestibular disorders.

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Observation of the morphology and calcium content of vestibular otoconia in rats after simulated weightlessness

Cited by 12 publications

References 8 publications

The Effects of Bilateral Vestibular Loss on Hippocampal Volume, Neuronal Number, and Cell Proliferation in Rats

The Effects of Bilateral Vestibular Loss on Hippocampal Volume, Neuronal Number, and Cell Proliferation in Rats

Repeated exposure attenuates the behavioral response of rats to static high magnetic fields

Interactions between Stress and Vestibular Compensation – A Review

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