Artikel
The Ginkgo biloba special extract EGb 761® inhibits auditory impairment and the overexpression of glutamate receptors in the auditory brainstem of Lewis rats repeatedly exposed to emotional stress
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Autoren
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Agnieszka Szczepek
- Charité, Berlin, Germany
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Uta Reich
- Charité, Berlin
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Heidi Olze
- Charité, Berlin
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Birgit Mazurek
- Charité, Berlin
| Veröffentlicht: | 30. März 2016 |
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Gliederung
Text
Recently, we have demonstrated that stress induces auditory hypersensitivity and changes gene expression in the auditory pathway of Wistar rats. Here, we studied the effect of stress on auditory performance of Lewis rats, a rat strain with a dysfunctional HPA-axis. In addition, we analysed the influence of EGb 761® on stress-induced changes. Over the whole experiment, female 4 wk old Lewis rats were fed with EGb 761®-containing chow (50 mg/kg bw body weight/d) or regular diet. After 1 week the animals were either not subjected to stress (ctrl), or stressed for 24h, which was repeated seven d later. Immediately, 3h, 6h, 24h, 1 wk and 2 wk after 2nd stress the auditory brainstem responses (ABR) were recorded. A subgroup of animals was sacrificed immediately, 3 h or 1wk after stress, the inferior colliculus was dissected and used for qPCR for genes involved in apoptosis, neural plasticity and stress response.
Lewis rats on control diet did not develop auditory hypersensitivity after repeated stress. By contrast, 1d and 1wk after 2nd stress, ABR thresholds increased. In general, EGb 761® did not affect hearing of ctrl rats. EGb 761® treated rats developed auditory hypersensitivity 3h and 6h after stress. The stress-induced hearing impairment was not seen in the EGb 761® group, and the gene expression response was also different from the control group. The most prevalent differences were in the expression of AMPA receptors (Gria2, Gria3) which were upregulated in the stressed control group and downregulated in the stressed EGb 761® group. In addition, Hif1α was upregulated in the EGb 761® group. The EGb 761®-mediated upregulation of Hif1 might improve microvascularisation, and down-regulation of AMPA-receptor genes might protect against excitotoxicity.
Supported by: Dr. Willmar Schwabe GmbH & Co. KG
Der Erstautor weist auf folgenden Interessenkonflikt hin: This presentation is a part of research performed under contract between the Charité and Dr. Willmar Schwabe GmbH & Co. KG.
