title: Expression of genes implicated in oxidative stress in the cochlea of newborn rats.
abstract: Oxidative stress is an important mechanism inducing ototoxicity-, age- and noise-induced hearing loss. To better understand this phenomenon, we examined cochlear tissues for the expression of following genes involved directly or indirectly in the oxidative stress response: glyceraldehyde-3-phosphate dehydrogenase (Gapdh); solute carrier family-2 (facilitated glucose transporter), member-1 (Slc2a1); heme oxygenase-1 (Hmox1); heme oxygenase-2 (Hmox2); inducible nitric oxide synthase-2 (Nos2); transferrin (Tf); transferrin receptor (Tfrc); glutathione S-transferase A3 (Gsta3) and metallothionein-1a (Mt1a). Cochlear tissues were dissected from the p3-p5 Wistar rats, divided into the organ of Corti (OC), modiolus (MOD) and stria vascularis together with spiral ligament (SV + SL) and processed immediately or cultured under normoxic conditions or a short-term, mild hypoxia followed by re-oxygenation. After 24 h, explants were collected and total RNA isolated, transcribed and amplified in the real time RT-PCR. We found all genes listed above expressed in the freshly isolated cochlear tissues. In the OC and MOD, Slc2a1, Tf, and Mt1a were expressed on a lower level than in the SV + SL. In the OC, Hmox1 was expressed on a lower level than in the MOD and SV + SL. Hypoxic and normoxic cultures increased the transcript number of Gapdh, Slc2a1 and Hmox1 in all cochlear tissues. The expression of Nos2, Tf, Gsta3 and Mt1a increased in a tissue-specific manner. In the SV + SL, Mt1a expression decreased after normoxic and hypoxic conditions. Taken together, using real time RT-PCR, our results imply that oxidative stress may be an important component of cochlear injury during the developing period. In spite of the immaturity of the tissue, a differential response of antioxidant enzymes/proteins with respect to the pathway, the expression levels and regions was observed.
authors: Molecular Biology Research Laboratory, Department of Otorhinolaryngology CCM, Charité-Universitätsmedizin Berlin, Berlin, Germany. birgit.mazurek@charite.de
authors: Birgit
authors: B
authors: Mazurek
authors: Nyamaa
authors: N
authors: Amarjargal
authors: Heidemarie
authors: H
authors: Haupt
authors: Julia
authors: J
authors: Fuchs
authors: Heidi
authors: H
authors: Olze
authors: Astrid
authors: A
authors: Machulik
authors: Johann
authors: J
authors: Gross
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D015687:Cell Hypoxia; D002470:Cell Survival; D003051:Cochlea / Q000378:metabolism* / Q000473:pathology; D005786:Gene Expression Regulation; D018384:Oxidative Stress / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D046509:Tissue Culture Techniques
chemical_list: D012333:RNA, Messenger