| Cells of all living organisms have a mechanism that enables them to survive environmental stressors. That mechanism, the heat -shock response, is characterized by an increase in the synthesis of a family of proteins called heat - shock or heat - stress proteins. The heat - shock protein ( HSP)70, has been the most widely studied because it is highly stress inducible and its sequence is highly conserved from bacteria to humans. During the heat - shock response, HSP70 assists in the folding and reassembly of denatured proteins, protecting the cell from an otherwise damaging stress, HSP70 also plays an integral role in certain biochemical events of normal cells, and, because of its antigenicity, HSP70 may have a role in the immune response.It is well known that the aminoglycosidic antibiotics ( AmAn) have the side-effects of nephrotoxicity and Ototoxicity. And the AmAn often give rise to nephric function decline, balance maladjustment. Even though, they are still widely used worldwide, especially in the developing countries. As they have many advantages, such as stable nature, wide anti - bacterial spectrum, strong antiseptic ability, easy to use and reasonable prices. The Ototoxicity of the AmAn is mainly due to its accumulation in inner ear and then damages the inner ear hair cells. It is reported that different kinds of damages and/or different cells can endure different degrees of gentamicin(GM) , and the transcription and the translation of HSP in different cells also defers obviously. Till now the effects of GM on the cochlea, the transcriptional expression and the translation of HSP in various cells is unknown and need to be studied further.In the past, it was usually regarded that injuried hair cell has no ability to repair. Recent studies showed hair cells of cochlea and vestibulum in birds and the hair cells of vestibulum in mammalian can be repaired to some degree after injury. Then whether injuried hair cells of cochlea have the ability to repair needs to study.Previous observation from our laboratory has shown that activity of NOS in the cochlea was inhibited after tetramethylpyrazine (TMP) -treatment, suggesting that TMP attenuated high amounts of NO in GM ototoxic guinea pig cochlea. It is not clear that whether the resistant effect and regeneration of TMP on ototox-icity of GM.Therefore, in the present study, by using auditory brain - stem response (ABR) test, HSP70 immunohistochemical staining and HSP70mRNA in situ hybridization staining, and scanning electron microscopy staining, observation expression of HSP70, HSPVOmRNA and regeneration of hair cells in GM ototox-icity guinea pig cochlea were observed, also we investigate whether TMP can effectively protect against GM ototoxicity and regenerate hair cells in GM ototoxici-ty guinea pig cochlea.MaterialsThe study was conducted on healthy albino guinea pigs of either sex (initially weighing 200 ~ 300g, with normal Preyer' s reflexes). GM sulfate was purchased from Shenyang No. 1 Pharmaceutical Factory. TMP injection was purchased from Qiqiha - er Pharmaceutical Factory. 25% glutaraldehyde: Sigma. HSP I - Ab, SABC ready - to - use kit, In situ hybridization kit for HSP, DAB are purchased from Boston Corp, Wuhan.Methods1. Experimental groups and preparation of AmAn ototoxicity model Animals were assigned to four groups: (1) GM alone, received 100mg/kgdaily by intraabdominal injections. (2) TMP + GM, received lOOmg/kg daily GM and 140mg/kg TMP daily at the same time by intra ?abdominal injections. (3) TMP alone, received 140mg/kg daily by intra -abdominal injections. (4) saline - injected controls. Duration of treatment was 10 days. Body weights were monitored daily, and the administered dose was adjusted accordingly.2. ABR testABR thresholds were recorded for each animal prior to the beginning of the study, and 1,3,7 14 and 30 days after the treatment of all kinds of drugs. Animals were anesthetized with 1% sodium pentobarbital 40mg/kg intra - abdominal injections. ABR thresholds were recorded using cl...
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