Effects of caloric vestibular stimulation on serotoninergic system in the media vestibular nuclei of guinea pigs / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Anatomic and electrophysiological studies have revealed that the neurons located in the media vestibular nuclei (MVN) receive most of the sensory vestibular input coming from the ipsilateral labyrinth and the responses of MVN neurons to caloric stimulation directly reflect changes in primary vestibular afferent activity. The aim of this study was to clarify the intrinsic characteristics of serotonin (5-hydroxytryptamine, 5-HT) release in the MVN during the period of vertigo induced by caloric stimulation.</p><p><b>METHODS</b>We used an in vivo microdialysis technique to examine the effects of caloric stimulation on the serotoninergic system in MVN. Twenty four guinea pigs were randomly divided into the groups of irrigation of the ear canal with hot water (n = 6), ice water (n = 6) and 37 degrees C water (n = 4), and the groups of irrigation of the auricle with hot water (n = 4) and ice water (n = 4), according to different caloric vestibular stimulation. We examined the animal's caloric nystagmus with a two-channel electronystagmographic recorder (ENG), and meanwhile examine serotonin (5-hydroxytryptamine, 5-HT) level in the MVN with microdialysis technique after caloric stimulation.</p><p><b>RESULTS</b>In the caloric test the hot water (44 degrees C) irrigation of the right external auditory canal induced horizontal nystagmus towards the right side lasting about 60 seconds and the ice water irrigation of the right external auditory canal induced it towards the left side lasting for about 90 seconds. No nystagmus was induced by 37 degrees C water irrigation of the external ear canal. Therefore, it was used as a negative control stimulation to the middle ear. The MVN 5-HT levels significantly increased in the first 5-minute collecting interval and increased to 254% and 189% of the control group in the second collecting interval in response to caloric vestibular stimulation with ice water and hot water respectively. The serotonin release was not distinctly changed by the irrigation of the auricle with ice water or hot water.</p><p><b>CONCLUSIONS</b>Neither somato-sensory stimulation of the middle ear nor nonspecific cold or hot stress affects the serotonin release. The rise of 5-HT in MVN may be involved in the mechanism of vertigo induced by caloric stimulation.</p>

Expression of antisecretory factor and aquaporin 1, 2 in the rat inner ear and their interaction / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To study the interaction among aquaporin1 (AQP), aquaporin2 (AQP2) and antisecretory factor( AF) , and their expression in the rat inner ear for furthur understanding of Meniere' s disease.</p><p><b>METHODS</b>Inner ear tissue section of six healthy male Sprague-Dawley rats was performed and Envision immunochemical staining was applied to detect the expression of AF, AQP1 and AQP2 in the rat inner ear. Vestibular and cochlear tissues of twenty healthy male Sprague-Dawley rats were dissected. Coimmunoprecipitation and Western Blot were used to specifically immunoprecipitate AF protein in the vestibular and cochlear tissues with monoclonal antibodies against AQP1 and polyclonal antibodies antibodies against AQP2 to detect the above precipitate with specific antibodies against AF.</p><p><b>RESULTS</b>(1) AF was widely distributed in the inner ear, such as marginal cells of stria vascularis , five classes of spiral ligament fibrocyte , Reissner's membrane, basilar membrane, ampullar crest and so on with mild or moderate staining. In addition, round membrane was moderately or markedly stained. Positive immunostaining was found in the cochlear spiral ganglion, vestibular nerve and cochlear nerve. AQP1 was distributed in the intermediate cells in stria vascularis, type III fibrocyte of spiral ligament, basilar membrane and round membrane with moderate to marked degree of immunostaining intensity. AQP2 was mainly localized to the type II, IV, and V fibrocyte of spiral ligament, with moderate to marked degree of immunostaining intensity, round membrane was weakly stained. (2) No band was observed in the control and a single immunoreactive band of 60 000 was observed, which was equal to the molecular mass of AF.</p><p><b>CONCLUSIONS</b>(1) AF, AQP1 and AQP2 have its individual specific localization in the rat inner ear, which was close to the parts of endolymph, so regulating water of the endolymph may be possible. (2) The range of localization of AF overlapped the distribution of AQP1 and AQP2. The results showed the existence of AF protein in the immunoprecipitate using co-immunoprecipitation combined with Western Blot. It suggested that the interaction between AQP1, AQP2 and AF might be possible.</p>

Expression of adrenomedullin in the tissue with laryngeal carcinoma / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To observe the expression of adrenomedullin (AM) in the patients with laryngeal carcinoma.</p><p><b>METHODS</b>Two-step immunohistochemistry method was used to examine the expression of AM in the patients with laryngeal carcinoma. Radioimmunoassay was applied to determine the concentration of AM in the laryngeal carcinoma tissues, adjacent laryngeal mucosa of carcinoma tissues and in the plasma of patients and controls.</p><p><b>RESULTS</b>Positive stainings for AM were found in all 21 specimen examined,distributed mainly in the cytoplasm of the laryngeal carcinoma cells. Positive stainings were more stronger in the circumference than in the center of tumor tissue for the highly and moderately differentiated tumors. While the stainings were distributed homogeneously for poorly and moderately differentiated tumors. The concentration of AM in the laryngeal carcinoma tissues (n = 44) and the adjacent mucosa (n = 44) were (49.67 +/- 28.33) pg/ml and (14.71 +/- 7.17) pg/ml (x +/- s) respectively and laryngeal tumor showed much higher concentration of AM than the adjacent mucosa (u = 135.00, P < 0.01). The concentration of AM in patients with laryngeal carcinoma of T2, T3 and T4 stage were (31.52 +/- 15.22), (56.63 +/- 18.51) and (96.12 +/- 18.22) pg/ml (x + s) respectively,and there were statistically significant difference among them. In the N stage, patients with higher stages were found to express significantly higher AM concentration, but there was not statistically significant difference between NO stage and N1 stage. In the M stage,patients with M1 stage were found to express significantly higher AM concentration (u = 31.00, P < 0.01). But there was not statistically significant difference between AM plasma concentration of laryngeal carcinoma patients and that of healthy controls.</p><p><b>CONCLUSIONS</b>The results suggested that high expression of AM in tissues of laryngeal carcinoma was related with the TNM stage of laryngeal carcinoma, AM may play an important role in the development of the laryngeal neoplasma.</p>

Inhibition of salicylate on potassium channels in rat inferior colliculus neurons / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To understand what role of the transient outward potassium channels and the delayed rectifier potassium channels play in the mechanism of salicylate-induced tinnitus.</p><p><b>METHODS</b>The effects of salicylate on the transient outward potassium channels and the delayed rectifier potassium channels in freshly dissociated inferior colliculus neurons of rats were studied, using the whole-cell voltage clamp method.</p><p><b>RESULTS</b>Salicylate blocked the transient outward potassium current (I(K(A and the delayed rectifier potassium current (I(K(DR in concentration-dependent manner (0.1-1 mmol/L). The IC50 values for the blocking action of salicylate on I(K(A)) and I(K(DR)) were 2.27 and 0.80 mmol/L, respectively. At a concentration of 1 mmol/L, salicylate did not shift the activation and inactivation curves of I(K(A)), but significantly shifted the activation and inactivation curves of I(K(DR)) negatively by approximately 11 mV and 24 mV.</p><p><b>CONCLUSIONS</b>Salicylate inhibits both I(K(A)) and I(K(DR)) in rat inferior colliculus neurons but only significantly affects the activation and inactivation kinetics of I(K(DR)). Effects of I(K(A)) and I(K(DR)), especially I(K(DR)), by salicylate may play an important role in salicylate-induced tinnitus.</p>