Abstract
Degeneration of neurons, such as the inner ear spiral ganglion neurons (SGN), may be decelerated or even stopped by neurotrophic factor treatment, such as brain-derived neurotrophic factor (BDNF), as well as electrical stimulation (ES). In a clinical setting, drug treatment of the SGN could start directly during implantation of a cochlear implant, whereas electrical stimulation begins days to weeks later. The present study was conducted to determine the effects of consecutive BDNF and ES treatments on SGN density and electrical responsiveness. An electrode drug delivery device was implanted in guinea pigs 3 weeks after deafening and five experimental groups were established: two groups received intracochlear infusion of artificial perilymph (AP) or BDNF; two groups were treated with AP respectively BDNF in addition to ES (AP + ES, BDNF + ES); and one group received BDNF from the day of implantation until day 34 followed by ES (BDNF ⇨ ES). Electrically evoked auditory brainstem responses were recorded. After one month of treatment, the tissue was harvested and the SGN density was assessed. The results show that consecutive treatment with BDNF and ES was as successful as the simultaneous combined treatment in terms of enhanced SGN density compared to the untreated contralateral side but not in regard to the numbers of protected cells.
Highlights
IntroductionCochlear implant technology is the state-of-the-art therapy for patients suffering from severe to Cochlear implapnrtotfeocuhnndolsoegnysoisritnheeusrtaalthe-eoafr-itnhge-laorstst.hDeruarpinygfosur rpgaetrieynatssisluicfofenrein-bgafsreodmelseecvtreoredetodevice is inserted in rofound sensorinetuhrealinhneearrienagr.loUssp
The results show that consecutive treatment with BDNF and Electrical stimulation (ES) was as successful as the simultaneous combined treatment in terms of enh2a.n9c. eHdisStoGloNgicdael nPsriotcyedcuormespared to the untreated contralateral side but not in regard to the numbersOonf pexropteercitmedenctealllsd. ay 48, 200 mL phosphate buffered saline (PBS) followed by 200 mL of 4%
Spiral Ganglion Cell Surv1ival within Each Group py for patients suffering froAmll ssuebvjeecrtes utosed in this stu0dy were implanted in the left cochlea, and the contralateral ear served ne-based electrode devaisceinitserinnaslecrotendtroinl
Summary
Cochlear implant technology is the state-of-the-art therapy for patients suffering from severe to Cochlear implapnrtotfeocuhnndolsoegnysoisritnheeusrtaalthe-eoafr-itnhge-laorstst.hDeruarpinygfosur rpgaetrieynatssisluicfofenrein-bgafsreodmelseecvtreoredetodevice is inserted in rofound sensorinetuhrealinhneearrienagr.loUssp. Dtou2ri2ngelesuctrrgoedrey caosniltiaccotnsee-lbeacsteridcaellleyctsrtoimdeudlaetveicreesiisdiunasleprteerdipinheral neurons of the e inner ear. NPeaurtriocnuslaorlfytahtethe electrode–nerve earing nerve and ailnlotewrfaachee, athrienrge aserenspaattihoonpfhoyrstihoelodgeicaaflppartoiecnetsss.ePs aorctcicuurrlainrlgywathtihche cealenctbreomdea–nniepruvleated by optimization terface, there aroef tpheatbhiooplohgyisciaollaosgpieccatls apnrdocceosmsebsinoatcicounrorifntghiswaphpicrhoacchanwitbhethme iamnippluanlatt.eOdneboyf the most important ptimization of the pbriooblolegmicaslwahspicehchtsinadnedrcfuormthbeinr iamtiopnroovfetmheisnat pofpcroocahclheawriitmhpthlaenitmouptlcaonmt. EOins ethoefstehceondary degeneration ost important proobfltehmestawrgheitchcehllisnodfeerlefcutrrtihcaelr sitmimpurolavteiomne,ntht eosfpcioraclhgleaanrgilmiopnlnaneut roountsco(SmGeNi)s [t1h].e. Sensorineural hearing loss is primarily caused by the loss of hair cells in the organ of Corti of the inner ear. The afferent fibers of the ain Sci. 2020, 10, x; doiS: FGONR PdEeEgReRnEeVraIEteWand subsequently the SGN and their cwenwtwra.ml dpprio.cjoemct/ijoounrsnadl/ibera[i2n–s4ci]. Brain Sci. 2020, 10, 559; doi:10.3390/brainsci10080559 www.mdpi.com/journal/brainsci
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