Abstract:

Objective:It has been known thatglial line-cell derived neurotrophic factor (GDNF) has the nutritional and protective effect in motor neurons. In this experiment, we investigated the character of GDNF mRNA expression in a facial nerve-striking model; combinedwith other scholarscexperimental results; and analyzedwhat role GDNF plays in the regeneration process of injured motor nerves.Methods:We established a strikingmodel in rabbitfacial nerveswith a striking gunwith the striking velocity of 10m/s and the total striking energy of 715J. Thenwe detected the GDNFmRNAexpression in facial neurons and axonswithin situhybridiza- tion on days 3, 7, 14 and 21 after striking. We counted the expression numbers of facial neurons and, compared with normal fa- cial neurons and peripheral facial nerves.Results:We detected GDNF mRNA expression in the facial neurons from day 3 to day 21 after the facial nerve injured by striking. The peak of GDNF mRNA expression appeared on the 7th day, and then the expres- sion number of facial neurons decreased gradually. Ahigh level expressionwas also detected on day 21. GDNFmRNA expression was not detected neither in Schwann cells nor in normal facial neurons from the 3rd day to the 21st day.Conclusion:GDNF is a kind of neurotrophic growing factor (NGF) that could be activated by injury. The characterofGDNFmRNAexpressionwas accor- dant to the process of nerve regeneration. These results showed thatGDNF plays a very important role in the regeneration of injured motor nerves.

Key words: glialline-cellderivedneurotrophicfactor, mRNA, facialnerve, striking, insituhybridization