pituitrin and Endolymphatic-Hydrops

It is well established that endolymphatic hydrops plays a role in Ménière disease, even though the precise role is not fully understood and the presence of hydrops in the ear does not always result in symptoms of the disease. It nevertheless follows that a scientific understanding of how hydrops arises, how it affects the function of the ear, and how it can be manipulated or reversed could contribute to the development of effective treatments for the disease. Measurements in animal models in which endolymphatic hydrops has been induced have given numerous insights into the relationships between hydrops and other pathologic and electrophysiological changes, and how these changes influence the function of the ear. The prominent role of the endolymphatic sac in endolymph volume regulation, and the cascade of histopathological and electrophysiological changes that are associated with chronic endolymphatic hydrops, have now been established. An increasing number of models are now available that allow specific aspects of the interrelationships to be studied. The yclical nature of Ménière symptoms gives hope that treatments can be developed to maintain the ear in permanent state of remission, possibly by controlling endolymphatic hydrops, thereby avoiding the rogressive damage and secondary pathologic changes that may also contribute to the patient's symptoms.

Topics: Acute Disease; Aldosterone; Animals; Chronic Disease; Cyclic AMP; Disease Models, Animal; Endolymph; Endolymphatic Hydrops; Endolymphatic Sac; Hearing Loss; Humans; Intracranial Pressure; Ion Transport; Lipopolysaccharides; Magnetic Resonance Imaging; Noise; Vasopressins

Endolymphatic hydrops is the pathologic feature associated with Meniere's disease. The development of endolymphatic hydrops appears to arise from multifactorial inheritance with alteration of endolymphatic homeostasis. Various factors associated with the phenomenon of hydrops include functional or anatomic obstruction of endolymphatic flow, malabsorption of endolymph, genetic anomalies, vasodilation, allergy, viral infection, and autoimmunity.

Topics: Animals; Autoimmunity; Endolymph; Endolymphatic Hydrops; Endolymphatic Sac; Guinea Pigs; Humans; Hypersensitivity; Meniere Disease; Mutation; Temporal Bone; Vasopressins; Virus Diseases

The etiology of Ménière's disease (MD) is still not completely clear, but it is believed to be associated with endolymphatic hydrops (EH), which is characterized by auditory functional disorders. Vasopressin injection in C57BL/6J mice can induce EH and serve as a model for MD. Optical Coherence Tomography (OCT) has shown its advantages as a non-invasive imaging method for observing EH.. C57BL/6J mice received 50 μg/100g/day vasopressin injections to induce EH. Auditory function was assessed using auditory brainstem response (ABR) and distortion product otoacoustic emissions (DPOAE). OCT was used to visualize the cochlea.. OCT observed accumulation of fluid within the scala media in the cochlear apex. ABR showed significant hearing loss after 4 weeks. DPOAE revealed low-frequency hearing loss at 2 weeks and widespread damage across frequencies at 4 weeks.. The development of hearing loss in mouse models of MD is consistent with EH manifestations.

Topics: Animals; Deafness; Endolymphatic Hydrops; Hearing Loss; Magnetic Resonance Imaging; Meniere Disease; Mice; Mice, Inbred C57BL; Tomography, Optical Coherence; Vasopressins

The symptoms of Meniere's disease (MD) are generally considered to be related to endolymphatic hydrops (EH). There are many recent reports supporting the possibility that vasopressin (VP) is closely linked to the formation of EH in Meniere's disease. Based on this, we developed a clinically relevant animal model of Meniere's disease in which a VP type 2 receptor agonist was administered after electrocauterization of the endolymphatic sac. We report live imaging of the internal structure, and functional changes of the inner ear after electrocauterization of the endolymphatic sac and administration of a VP type 2 receptor agonist. In this model, the development of EH was visualized in vivo using optical coherence tomography, there was no rupture of Reissner's membrane, and low-tone hearing loss and vertiginous attacks were observed. This study suggested that acute attacks are caused by the abrupt development of EH. This is the first report of live imaging of the development of EH induced by the administration of a VP type 2 receptor agonist.

Topics: Animals; Disease Models, Animal; Endolymphatic Hydrops; Meniere Disease; Tomography, Optical Coherence; Vasopressins; Vestibular Function Tests

The aim of the present study was to examine the association of neuro-otological examination, blood test, and scoring questionnaire data with treatment-resistant intractability in idiopathic benign paroxysmal positional vertigo (BPPV) patients.. We experienced 1520 successive vertigo/dizziness patients at the Vertigo/Dizziness Center in Nara Medical University during May 2014 to April 2018. Six hundred and eleven patients were diagnosed as BPPV (611/1520; 40.2%) according to the diagnostic guideline of the International Classification of Vestibular Disorder in 2015. Among BPPV patients, there were 201 intractable patients (201/611; 32.9%), 66 of whom were idiopathic and enrolled to be hospitalized and receive neuro-otological examinations, including the caloric test (C-test), vestibular evoked cervical myogenic potentials (cVEMP), subjective visual vertical (SVV), glycerol test (G-test), electrocochleogram (ECoG), inner ear magnetic resonance imaging (ieMRI), blood tests including anti-diuretic hormone (ADH) and bone alkaline phosphatase (BAP), and self-rating questionnaires of depression score (SDS). Sixty-six patients were diagnosed as horizontal type cupula (hBPPVcu; n=30), horizontal type canal (hBPPVca; n=10), posterior type (n=20), and probable and/or atypical BPPV (n=6). Data are presented as ratios (+) of the number of idiopathic BPPV patients with examination and questionnaire data outside of the normal range.. The ratio (+) data were as follows: C-test=21.2% (14/66), cVEMP=24.2% (16/66), SVV=48.5% (32/66), G-test=18.2% (12/66), ECoG=18.2% (12/66), ieMRI=12.1% (8/66), ADH=9.1% (6/66), BAP=13.6% (9/66), and SDS=37.9% (25/66). Multivariate regression analysis revealed that the periods of persistent vertigo/dizziness were significantly longer in BPPV patients with hBPPVcu, C-test (+), endolymphatic hydrops (+), and BAP (+) compared with those with negative findings.. Although patients with idiopathic BPPV are usually treatable and curable within 1 month, the presence of hBPPVcu, canal paresis, endolymphatic hydrops, and elevated BAP may make the disease intractable, and thus require additional treatments.

Topics: Aged; Alkaline Phosphatase; Audiometry, Evoked Response; Benign Paroxysmal Positional Vertigo; Caloric Tests; Endolymphatic Hydrops; Female; Humans; Magnetic Resonance Imaging; Male; Middle Aged; Multivariate Analysis; Neurophysins; Osteoporosis; Paresis; Protein Precursors; Regression Analysis; Semicircular Canals; Vasopressins; Vestibular Evoked Myogenic Potentials

We investigated the influence of vasopressin type 2 receptor antagonist (OPC-41061; Tolvaptan) on experimentally induced endolymphatic hydrops (EH) in guinea pigs. In the first series, the endolymphatic sac (ES) of the left ear of all animals was electrocauterized. Four weeks after surgery, the animals were allocated to four groups: three systemic applications groups (saline, OPC 10 and 100 mg/kg) and a local round window (RW) OPC 1 mg/body application group. We examined the histopathology of the temporal bones and assessed volumetric changes of the endolymphatic space in the cochlea and saccule. In the second series, we investigated the effects of systemic and topical applications of OPC on plasma vasopressin (p-VP) concentrations and plasma osmolality (p-OSM). In the first series, we found that EH was reduced in the OPC 10 mg/kg systemic and OPC RW application groups. In contrast, EH increased in the OPC 100 mg/kg systemic application group. In the second series, neither p-VP levels nor p-OSM were significantly different among the non-OPC, OPC 10 mg/kg systemic, and OPC RW application groups. However, in the OPC 100 mg/kg systemic application group, the p-VP level was significantly higher than that in other groups, and p-OSM was higher than that in the non-OPC group. The systemic application of a low dose of OPC and topical application of OPC resulted in reduced EH in the face of minimal systemic effects (p-VP and p-OSM). These findings suggest that OPC-41061 may be one useful treatment option for EH.

Topics: Administration, Oral; Administration, Topical; Animals; Antidiuretic Hormone Receptor Antagonists; Benzazepines; Disease Models, Animal; Endolymphatic Hydrops; Endolymphatic Sac; Female; Guinea Pigs; Meniere Disease; Osmolar Concentration; Receptors, Vasopressin; Tolvaptan; Vasopressins; Water-Electrolyte Balance

From histopathological specimens, endolymphatic hydrops has been demonstrated in association with inner ear disorders. Recent studies have observed findings suggestive of hydrops using MRI in humans. Previous studies suggest that vasopressin may play a critical role in endolymph homeostasis and may be involved in the development of Ménière's disease. In this study we evaluate the effect of vasopressin administration in vivo in longitudinal studies using two mouse strains. High resolution MRI at 9.4 T in combination with intraperitoneally delivered Gadolinium contrast, was performed before and after chronic subcutaneous administration of vasopressin via mini-osmotic pumps in the same mouse. A development of endolymphatic hydrops over time could be demonstrated in C57BL6 mice (5 mice, 2 and 4 weeks of administration) as well as in CBA/J mice (4 mice, 2 weeks of administration; 6 mice, 3 and 4 weeks of administration). In most C57BL6 mice hydrops developed first after more than 2 weeks while CBA/J mice had an earlier response. These results may suggest an in vivo model for studying endolymphatic hydrops and corroborates the future use of MRI as a tool in the diagnosis and treatment of inner ear diseases, such as Ménière's disease. MRI may also be developed as a critical tool in evaluating inner ear homeostasis in genetically modified mice, to augment the understanding of human disease.

Topics: Animals; Contrast Media; Disease Models, Animal; Ear, Inner; Edema; Endolymphatic Hydrops; Female; Gadolinium; Homeostasis; Infusions, Parenteral; Magnetic Resonance Imaging; Mice; Mice, Inbred C57BL; Mice, Inbred CBA; Osmosis; Vasopressins

There was no evidence of a mean raised vasopressin level in 80 subjects suffering from definite Meniere's disease with positive electrocochleographic findings. There was no correlation with stress. The only group with a mildly raised level comprised those who had had a vertigo attack within a day. The most likely cause is nausea, which is the most potent trigger for vasopressin release.. It has been claimed that patients with Meniere's disease have raised vasopressin levels. This has been linked with a long-standing notion that that there is a link between stress and Meniere's disease, so that an increase in vasopressin could trigger a vertigo attack.. Serum vasopressin concentrations were measured in 80 patients with Meniere's disease whose diagnosis was based on conventional symptom criteria plus electrocochleographic evidence of endolymphatic hydrops.. The community mean for vasopressin is 2.2 pmol/L (SD = 2.4). For all 80 Meniere's patients the mean vasopressin concentration was 2.1 pmol/L (SD = 1.6), and 2.8 pmol/L (SD = 0.9) when the last attack was within a day.

Topics: Adult; Aged; Aged, 80 and over; Audiometry, Evoked Response; Endolymphatic Hydrops; Female; Humans; Male; Meniere Disease; Middle Aged; Reference Values; Vasopressins; Young Adult

We reported previously that hyperactivation of vasopressin type-2 receptor (V2R)-mediated signaling in the endolymphatic sac could affect endolymphatic fluid metabolism, resulting in the pathogenesis of endolymphatic hydrops. Taken together with the present endolymphatic sac tumor (ELST) study, it is suggested that disorder of V2R signaling in the endolymphatic sac for any reason could be involved in the pathogenesis of endolymphatic hydrops. Although it is due to tumor genesis in ELST, it is idiopathic in nature in Meniere's disease.. We encountered two cases of ELST showing Meniere's disease-like symptoms. Both cases were suspected of having endolymphatic hydrops using neuro-otological examinations. To clarify the histopathological diagnosis of ELST and the molecular pathogenesis of endolymphatic hydrops, we performed histopathological and molecular biological examinations of the endolymphatic sac.. ELSTs in two rare cases were removed completely through the transmastoidal approach. V2R mRNA expression was examined using real-time PCR.. The first case was diagnosed as inflammatory granulation adjacent to the endolymphatic sac, i.e. pseudo-ELST, and the second case was diagnosed as papillary adenoma of ELST. V2R mRNA expression was up-regulated in the endolymphatic sac of both cases as seen in Meniere's disease compared with controls.

Topics: Adenoma; Adult; Audiometry, Pure-Tone; Diagnosis, Differential; Ear Neoplasms; Endolymphatic Hydrops; Endolymphatic Sac; Female; Gene Expression; Granuloma, Plasma Cell; Humans; Magnetic Resonance Imaging; Male; Mastoid; Meniere Disease; Middle Aged; Neuroma, Acoustic; Neurophysins; Protein Precursors; Real-Time Polymerase Chain Reaction; RNA, Messenger; Signal Transduction; Tomography, X-Ray Computed; Vasopressins; Vestibular Diseases

To investigate the ability to detect the in vivo cochlear changes associated with vasopressin-induced and surgically induced endolymphatic hydrops using MRI at 3 tesla (T).. Prospective, animal model.. Animal laboratory.. In group 1, five guinea pigs underwent post-gadolinium temporal bone MRI before and after seven and 14 days of chronic systemic administration of vasopressin by osmotic pump. In group 2, five guinea pigs underwent temporal bone MRI eight weeks after unilateral surgical ablation of the endolymphatic sac. Three-tesla high-resolution T1-weighted sequences were acquired pre- and postcontrast administration. Region of interest signal intensities of the perilymph and endolymph were analyzed manually. Quantitative evaluation of hydrops was measured histologically.. Gadolinium preferentially concentrated in the perilymph, allowing for distinction of cochlear compartments on 3.0-T MRI. The T1-weighted contrast MRI of vasopressin-induced hydropic cochlea showed significant increases in signal intensity of the endolymph and perilymph. Surgically induced unilateral hydropic cochlea also showed increased signal intensity, compared with the control cochlea of the same animal, but less of an increase than the vasopressin group. The histological degree of hydrops induced in the vasopressin group was comparable to previous studies.. In vivo postcontrast MRI of the inner ear demonstrated cochlear changes associated with chronic systemic administration of vasopressin and surgical ablation of the endolymphatic sac. Understanding the MRI appearance of endolymphatic hydrops induced by various methods contributes to the future use of MRI as a possible tool in the diagnosis and treatment of Ménière's disease.

Topics: Animals; Cochlea; Contrast Media; Disease Models, Animal; Endolymphatic Duct; Endolymphatic Hydrops; Endolymphatic Sac; Gadolinium; Guinea Pigs; Magnetic Resonance Imaging; Meniere Disease; Prospective Studies; Vasoconstrictor Agents; Vasopressins

To investigate the relationship between the plasma antidiuretic hormone (p-ADH) level, electrocochleogram (ECoG), and the glycerol test in patients with endolymphatic hydrops (ELH).. 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.. 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.. 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.

Topics: Audiometry, Evoked Response; Chi-Square Distribution; Endolymphatic Hydrops; Glycerol; Humans; Linear Models; Vasopressins

There are some kinds of sicknesses provoked by inadequate adaptation to physical and/or psychogenic stress in daily life. Delayed endolymphatic hydrops (DEH) is an inner ear disease like Ménière's disease (MD) characterized by episodic vertigo in the setting of preexisting unilateral deafness that especially occurs in civilized people with a stressful lifestyle. Its otopathologic finding was demonstrated to be inner ear endolymphatic hydrops through a temporal bone study in 1976, as in the case with MD in 1938. To elucidate the relationship between stress and the inner ear, we examined the plasma antidiuretic stress hormone vasopressin (pAVP) and its type 2 receptor (V2R) expression in the endolymphatic sac in patients with DEH.. A prospective molecular biological study.. Between 1998 and 2007, we enrolled 20 patients with ipsilateral DEH to examine their pAVP during remission from vertigo attacks. Plasma vasopressin was also examined in 87 patients with unilateral MD and 30 control patients with chronic otitis media. Using the real-time polymerase chain reaction method with tissue samples obtained during surgery, we examined V2R mRNA expression in the endolymphatic sac in 6 patients with ipsilateral DEH, 9 patients with unilateral MD, and 6 control patients with acoustic neuroma.. Plasma vasopressin (1.5 times versus controls; unpaired t test, p = 0.140) and V2R mRNA expression in the endolymphatic sac (35.8 times versus controls; unpaired t test, p = 0.002) were higher in patients with DEH compared with those with acoustic neuroma. There were no significant differences in pAVP or V2R expression in the endolymphatic sac between DEH and MD. Patients with DEH showed a significantly negative correlation between pAVP and V2R (Pearson test, r = -0.92, p = 0.009) as in those with MD (Pearson test, r = -0.68, p = 0.043).. Civilized people are frequently exposed to stress in their daily life, and pAVP can easily become elevated at any time. Therefore, a negative feedback system between pAVP and V2R in the endolymphatic sac may function for inner ear fluid homeostasis against stress-induced increases in pAVP. For the pathogenesis of endolymphatic hydrops resulting in vertigo attacks in patients with DEH as well as MD, pAVP may represent a matter of consequence, but V2R overexpression in the endolymphatic sac could be much more essential as a basis for these diseases.

Topics: Adult; Blotting, Western; Data Interpretation, Statistical; Endolymphatic Hydrops; Endolymphatic Sac; Female; Humans; Male; Meniere Disease; Middle Aged; Otologic Surgical Procedures; Prospective Studies; Receptors, Vasopressin; Reverse Transcriptase Polymerase Chain Reaction; RNA; Vasopressins; Vertigo

The p-ADH level in cases of juvenile unilateral profound deafness (JUPD) and the timecourse of the level were examined to investigate whether or not an increase of p-ADH is involved in the development of delayed endolymphatic hydrops (DEH) in JUPD.. In 90 consecutive patients with unilateral profound or total sensorineural deafness with the onset in early childhood, pure-tone audiometric examination and the measurement of p-ADH and plasma osmolality (p-OSM) were followed up once or twice a year as far as possible. At every testing, we performed careful history-taking about episodic vertigo/dizziness, fluctuant hearing loss, and tinnitus in order to find out whether patients had experienced these clinical signs of the development of DEH.. Means and standard deviation (S.D.) of p-ADH level and osmolality in all samples tested (n=368) were 7.3+/-7.0 pg/mL (0.7-52.0 pg/mL), and 288.6+/-4.4 mOsm/L (273-306 mOsm/L), respectively. The mean of p-ADH level was much higher than those previously reported in children and adolescents. High levels of p-ADH (over 5.0 pg/mL) were often observed in subjects between 6 and 19 years of age, but not so frequently in subjects of 20 years of age or older. Long-term follow-up of p-ADH levels revealed that DEH frequently developed in cases with persistent elevation of p-ADH.. The elevation of p-ADH is likely to promote the development of DEH in cases of JUPD, although the underlying mechanism remains to be elucidated.

Topics: Adolescent; Adult; Age Factors; Aged; Audiometry, Pure-Tone; Child; Child, Preschool; Deafness; Endolymphatic Hydrops; Female; Humans; Male; Meniere Disease; Middle Aged; Neurophysins; Osmolar Concentration; Protein Precursors; Reference Values; Vasopressins

There is evidence to suggest that water homeostasis in the inner ear is regulated via the vasopressin (VP)-aquaporin 2 (AQP2) system in the same fashion as in the kidney. The VP-AQP2 system in the kidney is well known to be inhibited by lithium, resulting in polyuria due to a decrease in reabsorption of water in the collecting duct of the kidney. Therefore, lithium is also likely to inhibit the VP-AQP2 system in the inner ear, and consequently exert some influence on inner ear fluid homeostasis. In this study, we investigated the effects of lithium on AQP2 expression in the rat inner ear, and on the cochlear fluid volume in hydropic ears of guinea pigs. A quantitative PCR study revealed that lithium reduced AQP2 mRNA expression in the cochlea and endolymphatic sac. Lithium application also decreased the immunoreactivity of AQP2 in the cochlea and endolymphatic sac. In a morphological study, lithium intake significantly reduced endolymphatic hydrops dose-dependently. These results indicate that lithium acts on the VP-AQP2 system in the inner ear, consequently producing a dehydratic effect on the endolymphatic compartment.

Topics: Animals; Aquaporin 2; Dose-Response Relationship, Drug; Endolymph; Endolymphatic Hydrops; Gene Expression; Guinea Pigs; Homeostasis; Immunohistochemistry; Lithium; Microscopy, Confocal; Polymerase Chain Reaction; Rats; RNA, Messenger; Vasopressins

In the present study, two experiments were performed to investigate the influence of OPC-31260 on experimentally induced endolymphatic hydrops in guinea pigs and the regulation of aquaporin-2 (AQP2) mRNA expression in the rat inner ear. In morphological studies, the increases in the ratios of the length of Reissner's membrane (IR-L) and the cross-sectional area of the scala media (IR-S) were quantitatively assessed among normal guinea pigs (normal ears) and three groups with hydropic ears: hydropic ears with no infusion (non-infusion hydropic ears), hydropic ears with an infusion of physiological saline into the scala tympani (saline-infused hydropic ears) and hydropic ears with infusion of 0.3% OPC-31260 into the scala tympani (OPC-infused hydropic ears). IR-Ls in the experimental groups were markedly larger than in the normal ear group, but there was no significant difference among the groups of non-infusion hydropic ears, saline-infused hydropic ears and OPC-infused hydropic ears. The IR-Ss of non-infusion hydropic ears and saline-infused hydropic ears (48.8-49.3%) were statistically different from that of normal ears (6.5%) (Dunnet multiple comparison test, P<0.01). However, IR-S of the OPC-infused hydropic ears (-14.8%) was significantly smaller than those of non-infusion hydropic ears and saline-infused hydropic ears (one-way ANOVA, P<0.01). In the quantitative polymerase chain reaction study, a comparison of the ratio of AQP2 and beta-actin mRNA (MAQP2/Mbeta-actin) was made between water-injected and OPC-31260-injected rats. An intravenous injection of OPC-31260 resulted in a significant decrease in MAQP2/Mbeta-actin both in the cochlea and in the endolymphatic sac (t-test, P<0.001). These results indicate that water homeostasis in the inner ear is regulated via the vasopressin-AQP2 system, and that the vasopressin type-2 antagonist OPC-31260 is a promising drug in the treatment of Meniere's disease.

Topics: Analysis of Variance; Animals; Antidiuretic Hormone Receptor Antagonists; Aquaporin 2; Aquaporins; Benzazepines; Endolymphatic Hydrops; Endolymphatic Sac; Gene Expression Regulation; Guinea Pigs; Male; Osmotic Pressure; Rats; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Vasopressins

Topics: Animals; Aquaporin 2; Aquaporin 6; Aquaporins; Endolymphatic Hydrops; Humans; Meniere Disease; Receptors, Vasopressin; Vasopressins

Recently, many lines of evidence have supported the possibilities that vasopressin (VP) is closely linked to the formation of endolymphatic hydrops in Meniere's disease. In the present study, it was examined whether or not the chronic administration of VP might induce endolymphatic hydrops. For this purpose, histological studies and VP radioimmunoassay were independently performed in 20 and 40 guinea pigs, respectively. The degree of hydrops was quantitatively assessed by the increase ratio (IR) of the scala media area in the mid-modiolar sections of the cochlea. The IR was defined by the following equation: 100x(A-B)/B (A: the cross-sectional area of the bulging scala media; B: the no-bulging scala media, enclosed by an idealized straight Reissner's membrane). VP was administered at the rates of 200 microU/kg/min, 400 microU/kg/min and 1000 microU/kg/min for 1 week via the osmotic mini-pump. The IR of the total of the apical, second, third and basal turns (means+/-S.D.s) were 4.4+/-0.7, 10.4+/-1.8, 17.4+/-7.9 (n=10 ears, each) in respective doses of VP. Comparing with that of the control animals (5.2+/-1.7, n=10 ears), the area increased significantly in the VP dosage of 400 and 1000 microU/kg/min (Bonferroni's method, P<0.05). Plasma VP concentrations produced by the VP administration in these dosages were 2.2+/-0.4, 3.5+/-0.8 and 14.0+/-3.9 (n=10, each) pg/ml. Although 3.5 pg/ml is the upper limit of plasma VP concentration in normal human subjects, 14.0 pg/ml was almost the same concentration as those observed in the acute phase of Meniere's disease (Takeda et al., 1995). Therefore, the formation of endolymphatic hydrops in cases of Meniere's disease might be caused by high concentrations of plasma VP.

Topics: Analysis of Variance; Animals; Arginine Vasopressin; Cochlea; Cochlear Duct; Dose-Response Relationship, Drug; Endolymphatic Hydrops; Guinea Pigs; Vasopressins

Plasma antidiuretic hormone (p-ADH) concentrations were determined with a radioimmunoassay, using a reversed-phase C18 silica column, in 300 patients with vertigo, dizziness and/or deafness; 119 of them had a diagnosis of Menière's disease. The p-ADH level was significantly elevated in patients with Meniere's disease and others with endolymphatic hydrops, e.g. cochlear Menière's disease or delayed hydrops. By contrast, the p-ADH level was not so high in cases without the endolymphatic hydrops. The increase in the p-ADH level was closely linked to vertigo attacks, the glycerol test results and an enhanced negative summating potential (-SP) in electrocochleogram (ECochG). These results lead to the assumption that disorders of ADH-dependent hormonal control in the inner ear may constitute the possible mechanism underlying vertiginous attacks and deafness in patients with endolymphatic hydrops.

Topics: Cochlea; Deafness; Dizziness; Edema; Electrophysiology; Endolymphatic Hydrops; Glycerol; Heating; Humans; Meniere Disease; Vasopressins; Vertigo

Clinical studies have shown that plasma vasopressin level is significantly elevated in patients with Meniere's disease. Other reports indicated that histamine induced a very quick and high elevation of vasopressin level and caused nystagmus in experimentally produced endolymphatic hydrops. We became interested in further investigating the details of this relationship by studying the effect of experimental endolymphatic hydrops and histamine upon plasma vasopressin level in the guinea pig. The results are as follows: 1) Histamine increased the plasma vasopressin level in normal guinea pigs. 2) There was no statistically significant difference in the plasma vasopressin level between the hydrops model and normal guinea pigs. 3) Histamine increased the plasma vasopressin level more in the hydrops model group than in normals. 4) Plasma vasopressin level was elevated in the vertiginous model caused by inner ear anesthesia. Our results support those of clinical investigators who reported that the plasma vasopressin level was elevated more in the Meniere's disease group than any other equilibrium disorder group. It is possible that vasopressin is in someway involved in the development of endolymphatic hydrops.

Topics: Animals; Endolymphatic Hydrops; Guinea Pigs; Histamine; Osmolar Concentration; Vasopressins