Abstract:

Objective   o observe variations of the brain-derived neurotrophic factor (bdnf) and c-fos and their proteins induced by auditory deprivation and intracochlear electrical stimulation in the auditory cortex, inferior colliculus and cochlear nucleus in infant rats. Methods   Sixty-six SD infant rats were randomly divided into 6 groups：the 4-week group(group A1), the 6-week group (group B1)with injection of ototoxic drug and their homologus control group(group A2，B2), the 3-week group(group C), and the 5-week group(group D)with injection of ototoxic drug with intracochlear electrical stimulation for one week. Each group consisted of 11 rats. Gentamicin sulphate (350mg/kg body weight) and frusemide (200mg/kg body weight) were subcutaneously injected in the skin folds on the lateral abdominal side and the dorsal neck area. Expressions of mRNAs and proteins encoded by bdnf and c-fos were detected by real-time PCR and immunohistological staining. Results   Real-time PCR and immunohistochemistry revealed that expressions of mRNAs and proteins encoded by bdnf and c-fos significantly increased in group A1 as compared to group A2, and decreased as compared to group C (P＜0.05), in the auditory cortex, inferior colliculus and cochlear nucleus. However, expressions of them significantly decreased in the group B1 as compared to group B2 and group D (P＜0.05). Conclusion   Auditory deprivation results in expressions of mRNAs and proteins encoded by bdnf and c-fos increas in early stage and decreasing in the later stage in auditory cortex, inferior colliculus and cochlear nucleus. Intracochlear electrical stimulation makes expression of them increase in rats with auditory deprivation. The dynamic variations of bdnf and c-fos and their proteins reflected the plasticity in neurons of the auditory pathway．

Key words: Auditory plasticity; Brainderived neurotrophic factor; c-fos; Electrical stimulation; Sensorineural hearing loss