Glial cell line-derived neurotrophic factor (GDNF) and its receptors GFR alpha-1 and GFR alpha-2 in the human testis

Glial cell line-derived neurotrophic factor (GDNF) and its receptors GFR al pha -1 and GFR alpha -2 were found in the human testis during fetal develop ment (15-34 weeks of gestation) and in adult men (51-86 years of age) by me ans of RT-PCR, immunohistochemistry and Western blot techniques. Gene expre ssion of GDNF could be established in the human testis and immunoreactivity (IR) for GDNF was detectable in Leydig cells, Sertoli cells, some spermato cytes and round spermatids as well as in smooth muscle cells of the wall of arterioles and small arteries. In the adult human testis, Sertoli and Leyd ig cells showed GFR alpha -1-IR, whereas GFR alpha -2-IR was located exclus ively in Leydig cells. Different to man, in the rat GDNF-IR in Sertoli cell s was detectable only until postnatal day 10, providing evidence for specie s related variability in the expression of GDNF. These findings suggest a c ritical role for GDNF during the differentiation of testicular structures a nd provide evidence for an additional important function in the adult human and rodent testis.