Effect of nigrostriatal damage induced by 6-hydroxydopamine on the expression of glial cell line–derived neurotrophic factor in the striatum of the rat

Several types of brain injuries have been associated with alterations in the striatal expression of neurotrophic factors, including glial cell line–derived neurotrophic factor (GDNF). However, contradictory results on the striatal expression of GDNF have been reported in different animal models of Parkinson's disease. For this reason, we examined the effect of nigrostriatal damage on the mRNA and protein expression levels of GDNF in the striatum as a function of time following a striatal or medial forebrain bundle 6-hydroxydopamine lesion. At different time points after the administration of 6-hydroxydopamine, striatal expression levels of GDNF were analyzed with semi-quantitative Western blotting. No significant changes in GDNF expression levels were observed within the 35-day observation period, either between the denervated and the intact striatum of medial forebrain bundle and striatally lesioned rats or between the striata of lesioned animals and those of control animals. In order to reinforce these results, striata of lesioned rats, sacrificed 18 days after lesioning, were analyzed with enzyme-linked immunosorbent assay and real-time polymerase chain reaction. At this time point, both techniques confirmed the results of the Western blot analysis, detecting no changes in striatal expression of GDNF, either at the protein level, or at the mRNA level. These data show that nigrostriatal damage induced by 6-hydroxydopamine has no effect on the striatal expression of GDNF.