Effects of er-long-zuo-ci-wan on the spontaneous activities of auditory central nucleus in rat model of tinnitus induced by salicylate acid / 中国应用生理学杂志

<p><b>AIM</b>Observe the effects of er-long-zuo-ci-wan (EIZCW, a compound of Chinese Traditional Medicine) on the spontaneous discharge of external cortex of inferior colliculus (ICx) and secondary auditory cortex (AII) of chronic tinnitus model rats induced by salicylate acid, to explore the neural mechanisms underlying ELZCW preventing tinnitus.</p><p><b>METHODS</b>30 adult SD rats were involved and divided into three groups, normal control group, chronic tinnitus model group and ELZCW prevention group. Extracellular recording techniques and stereotaxic method were used. The spontaneous spikes were recorded and analyzed from ICx and all in different group rats. The average rate of spontaneous discharge and the interspike interval histogram of spontaneous activities were used as indexes.</p><p><b>RESULTS</b>(1) Compared with normal control group, the average rate of spontaneous discharge recorded from the ICx in the chronic tinnitus model group increased significantly (4.57 +/- 0.54 Hz vs. 3.14 +/- 0.40 Hz, P < 0.05). Furthermore analysis showed that the discharge rate of short spike interval from the ICx in the chronic tinnitus model group increased than that of the normal group (0-40 ms: 58% vs. 40%; 0-4 ms: 9% vs. 5%). And there was an increasing tendency of the average rate of spontaneous discharge recorded from the AII in the chronic tinnitus model group compared with that in the normal group. (2) Compared with the chronic tinnitus model group, the average rate of spontaneous discharge recorded from the ICx and AII in the ELZCW prevention group significantly decreased than that in the chronic tinnitus model group (ICx: 2.41 +/- 0.21 Hz vs. 4.57 +/- 0.54 Hz, P < 0.01. AII: 2.24 +/- 0.24 Hz vs. 4.57 +/- 0.54 Hz , P < 0.01). And the discharge rate of short spike interval from the ICx and AII in the chronic tinnitus model group decreased than that in the normal control group (ICx: 0-40 ms 50% vs. 58%, 0-4 ms 4% vs. 9%. All: 0-22 ms: 24% vs. 31%, 0-8 ms 19% vs. 16%).</p><p><b>CONCLUSION</b>If the increasing of the spontaneous activities of ICx and AII in chronic tinnitus rats means tinnitus, the use of ELZCW could decrease this kind of changes.</p>

Establishing a simple method for detecting tinnitus of rats by using behavioral response of conditioned escape / 中国应用生理学杂志

<p><b>AIM</b>To create a simple behavioral procedure for detecting tinnitus of rats.</p><p><b>METHODS</b>A procedure based on a Pavlovian-conditioned suppression paradigm was set referencing Jastreboff's way to detect tinnitus behaviorally in conscious animals. Rats received acquisition training through Pavlovian conditioning to associate the conditioned stimulus (noise offset) with the unavoidable unconditioned stimulus (foot-shock). The manifestation here is escape reaction. An extinction procedure followed, during which the subject was exposed to the conditioned stimulus, but shock is no longer given. The manifestations of the rats in different group during the extinction processes were observed. Tinnitus was induced by salicylate (SA) injection to validate the method.</p><p><b>RESULTS</b>The escaped rate of SA group is lower than that of the control. It indicated that the SA rats escaped seldom when there was a sound off, because the rats might perceive the salicylate-induced auditory sensation as a substitute for the background noise that had acquired a safety value during training.</p><p><b>CONCLUSION</b>The behavioral procedure could be used to detect tinnitus of rats induced by salicylate.</p>