[In vitro neurite outgrowth induced by BDNF and GDNF in combination with dexamethasone on cultured spiral ganglion cells].
BACKGROUND
The efficacy of cochlear implant performance depends, among many other factors, on the number of excitable spiral ganglion cells (SGCs) and the nerve-electrode interface. In earlier animal studies it has been demonstrated that neurotrophic factors are effective to improve SGC survival after experimentally induced deafness. With regard to their anti-inflammatoric and anti-proliferative effects, glucocorticoids (e. g. dexamethasone) are potentially interesting therapeutic agents to reduce connective tissue formation around the inserted electrode. The biological effects of a combined intervention of neurotrophic factors with steroids on SGCs are unknown. Therefore the objective of the study was to investigate possible trophic or even toxic effects of brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF) and dexamethasone on neurite outgrowth of cultivated SGCs.


METHODS
By using dissociated postnatal spiral ganglion cells (p3-5) for cultivation in the present study, the influence of the mentioned factors in various concentrations and combinations on neurite outgrowth of SGCs was analysed.


RESULTS
Our results indicate significant trophic effects for BDNF (50 ng/ml) and a combination of BDNF with dexamethasone (100 ng/ml) on SGC neurite outgrowth. In contrast, single application of GDNF or dexamethasone in different concentrations caused no significant changes on neurite outgrowth when compared to the control condition.


CONCLUSIONS
Neurite outgrowth induced by neurotrophic factors could not be observed to be reduced when dexamethasone is given at the same time. Therefore the demonstrated results provide a basis for further animal studies in this field of research.
Stöver
T
T
Hals-Nasen-Ohrenklinik der Medizinischen Hochschule Hannover. Stoever.Timo@MH-Hannover.de
Scheper
V
V
Diensthuber
M
M
Lenarz
T
T
Wefstaedt
P
P
D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000008:administration & dosage / Q000494:pharmacology*; D003907:Dexamethasone / Q000008:administration & dosage / Q000494:pharmacology*; D004338:Drug Combinations; D051100:Glial Cell Line-Derived Neurotrophic Factor / Q000008:administration & dosage / Q000494:pharmacology*; D005938:Glucocorticoids / Q000008:administration & dosage / Q000494:pharmacology*; D016501:Neurites / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012106:Research; D013136:Spiral Ganglion / Q000166:cytology* / Q000187:drug effects*; D013997:Time Factors
D019208:Brain-Derived Neurotrophic Factor; D004338:Drug Combinations; D051100:Glial Cell Line-Derived Neurotrophic Factor; D005938:Glucocorticoids; D003907:Dexamethasone