ABSTRACT
Objective To investigate whether blocking NR2B receptor can reverse the process of cytotoxicity to spiral ganglion neurons induced by sodium salicylate in guinea pig by applying ifenprodil (a NR2B antagonist) at the round window niche .Methods Sixty healthy guinea pigs provided by the experimental animal center of Guangxi medical university were randomly and evenly divided into a control group (Group I ,no treatment) ,an APL group (Group II ,60μl APL directly applied to the round window ) ,a sodium salicylate group (Group III ,60 μl APL di-rectly applied to the round window and then be given intraperitoneal sodium salicylate injection ) ,and an ifenprodil group (Group IV ,60μl of 10μmol/l ifenprodil in APL directly applied to the round window and then be given intra-peritoneal sodium salicylate injection ) .Sodium salicylate was given at 400 mg · kg -1 · d-1 for 7 days .Auditory brainstem responses (ABRs) were recorded before animal sacrifice by decapitation .The left cochlea was removed and prepared for detection of caspase -3 expression in spiral ganglion neurons via immunohistochemistry .From each group ,6 cochleae were used to test apoptosis index in spiral ganglion neurons using the TUNEL technique .Results Before salicylate administration ,the ABR threshold was less than 40 dB SPL in all animals .After salicylate ad-ministration ,the ABR threshold was 33 .33 ± 5 .17 dB SPL in Group II ,64 .17 ± 7 .36 dB SPL in Group III and 49 .17 ± 5 .85 dB SPL in Group IV ,in contrast to 31 .67 ± 5 .16 dB SPL in Group I (controls) .The caspase -3 ex-pression was not changed obviously in Group I and Group II ,but was significantly changed in Group III and Group IV (P<0 .01) .The caspase-3 expression appeared to be decreased in Group IV compared to those in Groups III (P<0 .05) ,but still increased compared to those of in Group I and II (P<0 .05) .The apoptosis index among spiral ganglion neurons in Groups III and IV increased significantly compared to those of in Group I and II (P<0 .001) .It was however ,lower in Group IV than in Group III (P<0 .01) .Conclusion Blocking NR2B receptor with specificity can reverse the process of cytotoxicity to spiral ganglion neurons induced by sodium salicylate in guinea pig .
ABSTRACT
<p><b>OBJECTIVE</b>To observe the influence of betahistine on the expression of histamine H3 receptor in the medial vestibular nucleus (MVN) following unilateral labyrinthectomy (UL).</p><p><b>METHODS</b>Fifty-six healthy guinea pigs were randomly divided into three groups:the sham-operated group (group I), the UL group[group II, and UL+betahistine (BET) group (group III)], BET was intraperitoneally injection at 2.17 mg×kg(-1)×d(-1) for 7 days. The expression of histamine H3 receptor was analyzed by immunohistochemistry at 1 day, 3 days and 7 days after UL.</p><p><b>RESULTS</b>H3 receptors were presented in the MVN and the expression of histamine H3 receptor were increased significantly in the ipsilateral MVN at 1 and 3 days after UL(P < 0.05), the change turned into the normal value at 7 days(P > 0.05). In the UL+BET group, the intensity of histamine H3 receptor was lower than that in the UL at 1 day and 3 days(4.25 ± 0.71, 3.50 ± 0.92 vs 5.75 ± 0.71, 5.50 ± 0.93, P < 0.05). However, the changes turned into the normal values at 3 and 7 days (P > 0.05).</p><p><b>CONCLUSIONS</b>The early stage of the vestibular compensation process may be associated with the change of H3 receptor expression in MVN. In the UL+BET group the histamine H3 receptor recovered quickly.</p>