Effects of Lithium on Endolymph Homeostasis and Experimentally Induced Endolymphatic Hydrops

Fukushima, Kei; Takeda, Taizo; Kakigi, Akinobu; Takeda, Setsuko; Sawada, Shoichi; Nishioka, Rie; Azuma, Hiroshi; Taguchi, Takehito

doi:10.1159/000089409

Cited by 23 publications

(19 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Previous studies have shown that AQP2 protein and/or mRNA are expressed in the inner ear of rats. 19,39,46 Furthermore, the V2 receptor and/or its mRNA are found in the cochlea. 16,18 These previous studies suggest that water homeostasis in the inner ear is partly regulated via the VP-AQP2 system.…”

Section: Discussionmentioning

confidence: 99%

Morphological and functional changes in a new animal model of Ménière's disease

Egami

Kakigi

Sakamoto

et al. 2013

Laboratory Investigation

View full text Add to dashboard Cite

The purpose of this study was to clarify the underlying mechanism of vertiginous attacks in Ménière's disease (MD) while obtaining insight into water homeostasis in the inner ear using a new animal model. We conducted both histopathological and functional assessment of the vestibular system in the guinea-pig. In the first experiment, all animals were maintained 1 or 4 weeks after electrocauterization of the endolymphatic sac of the left ear and were given either saline or desmopressin (vasopressin type 2 receptor agonist). The temporal bones from both ears were harvested and the extent of endolymphatic hydrops was quantitatively assessed. In the second experiment, either 1 or 4 weeks after surgery, animals were assessed for balance disorders and nystagmus after the administration of saline or desmopressin. In the first experiment, the proportion of endolymphatic space in the cochlea and the saccule was significantly greater in ears that survived for 4 weeks after surgery and were given desmopressin compared with other groups. In the second experiment, all animals that underwent surgery and were given desmopressin showed spontaneous nystagmus and balance disorder, whereas all animals that had surgery but without desmopressin administration were asymptomatic. Our animal model induced severe endolymphatic hydrops in the cochlea and the saccule, and showed episodes of balance disorder along with spontaneous nystagmus. These findings suggest that administration of desmopressin can exacerbate endolymphatic hydrops because of acute V2 (vasopressin type 2 receptor)-mediated effects, and, when combined with endolymphathic sac dysfunction, can cause temporary vestibular abnormalities that are similar to the vertiginous attacks in patients with MD. Ménière's disease (MD) is a well-known inner ear disorder characterized by symptoms including recurring attacks of vertigo typically lasting for hours, fluctuating sensorineural hearing loss, and tinnitus. Since the milestone findings on the temporal bones of MD patients, 1,2 endolymphatic hydrops (EH) has been considered as the histopathological origin of MD, as characteristic morphological changes were reported to be produced by surgical obstruction of the endolymphatic sac (ES) in guinea-pig. 3 This observation indicates that malabsorption of endolymph in the ES is one of the possible mechanisms underlying the development of EH. This experimentally induced EH has been frequently used as an animal model to investigate the pathogenesis of inner ear disorders associated with EH. In terms of vestibular function, while canal dysfunction and/or spontaneous nystagmus have been occasionally observed in this animal model, 4,5 episodes of vertiginous attack or balance disorder have only rarely been observed. 6 In other words, this model is insufficient for fully representing the common symptoms of MD.Water homeostasis of the inner ear is essential for maintaining the functions of hearing and balance. EH is considered to be the result of disruption of inner ear water homeostasis, which ...

show abstract

Section: Discussionmentioning

confidence: 99%

Morphological and functional changes in a new animal model of Ménière's disease

Egami

Kakigi

Sakamoto

et al. 2013

Laboratory Investigation

View full text Add to dashboard Cite

show abstract

“…They noted that the stria vascularis, which was a possible site of the production of endolymph, showed no AQP2 immunoreactivity. On the other hand, our recent histochemical studies [11,13,27] revealed that AQP2 proteins were clearly expressed in the rat stria vascularis and the rat/human endolymphatic sac ( fig. 5 ).…”

Section: Hormonal Aspects Of MD On the Basis Of Experimental Studiesmentioning

confidence: 99%

“…8 ). Decompression of the endolymphatic space was also produced by the application of lithium, one of the VP-AQP2 system inhibitors [27] . These experimental results could open up possibilities for new therapeutic methods for MD.…”

Section: Hormonal Aspects Of MD On the Basis Of Clinical And Experimementioning

confidence: 99%

Hormonal Aspects of Ménière’s Disease on the Basis of Clinical and Experimental Studies

Takeda

Kakigi

et al. 2009

ORL

View full text Add to dashboard Cite

Conclusions: Endolymph homeostasis is thought to be mediated by the vasopressin-aquaporin-2 (VP-AQP2) system in the inner ear. Endolymphatic hydrops, the morphological characteristics of Ménière’s disease (MD), seems to reflect the malregulation of the VP-AQP2 system in inner ear fluid. The elevation of plasma vasopressin (p-VP) level, which is often observed in MD and its related diseases, might be one of the causative factors underlying these diseases. Purpose of Review: Review of the role of the VP-AQP2 system in the inner ear fluid homeostasis and in the formation and development of endolymphatic hydrops. Recent Clinical and Experimental Findings: A clinical survey has revealed that the p-VP level is often elevated in MD and its related diseases and that the increase in the p-VP level was closely linked to vertigo attacks in MD. Experimental studies have revealed that proteins and mRNAs of aquaporin-2 and vasopressin type 2 receptor were expressed in the stria vascularis of the cochlea and the epithelium of the endolymphatic sac, and that the volume of the endolymphatic compartment was mediated by the activity of the VP-AQP2 system in the inner ear.

show abstract

“…Previously, we reported that the plasma antidiuretic hormone (p-ADH) level is increased in patients with ELH [5] . In an experimental study, we reported that chronic administration of ADH induced ELH in guinea pigs [6] , and that aquaporin-2 (AQP2), an ADH-dependent water channel in the stria vascularis and the endolymphatic sac in the rat inner ear, was controlled by ADH [7,8] . Therefore, measurement of p-ADH seems useful as a test to confirm suspected ELH.…”

Section: Introductionmentioning

confidence: 99%

Diagnostic Value of Plasma Antidiuretic Hormone, Electrocochleography, and Glycerol Test in Patients with Endolymphatic Hydrops

Taguchi

Kakigi²,

Takeda³

et al. 2009

ORL

View full text Add to dashboard Cite

Objective: To investigate the relationship between the plasma antidiuretic hormone (p-ADH) level, electrocochleogram (ECoG), and the glycerol test in patients with endolymphatic hydrops (ELH). Patients and Methods: The subjects were 60 patients, including 51 with Ménière’s disease (except for cochlear Ménière’s disease), 7 with delayed ELH, and 2 with syphilitic ELH. The time period for measurements of the p-ADH level, ECoG and the glycerol test was within 4 weeks. Results: 13 patients showed positive results for all tests. 58 patients showed positive results for at least one of three tests. Only 2 patients showed negative results for all tests. Conclusion: The p-ADH level, ECoG and the glycerol test show different selectivity of ELH detection. It is useful to perform all three tests to diagnose ELH.

show abstract

Effects of Lithium on Endolymph Homeostasis and Experimentally Induced Endolymphatic Hydrops

Cited by 23 publications

References 42 publications

Morphological and functional changes in a new animal model of Ménière's disease

Morphological and functional changes in a new animal model of Ménière's disease

Hormonal Aspects of Ménière’s Disease on the Basis of Clinical and Experimental Studies

Diagnostic Value of Plasma Antidiuretic Hormone, Electrocochleography, and Glycerol Test in Patients with Endolymphatic Hydrops

Contact Info

Product

Resources

About