GDNF and NGF family members and receptors in human fetal and adult spinal cord and dorsal root ganglia

We describe the expression of mRNA encoding ligands and receptors of member s of the GDNF family and members of the neurotrophin family in the adult hu man Spinal cord and dorsal root ganglia (DRG). Fetal human spinal cord and ganglia were investigated for the presence of ligands and receptors of the neurotrophin family. Tissues were collected from human organ donors and aft er routine elective abortions. Messenger RNA was found encoding RET, GFR al pha -1, BDNF, trkB, and trkC in the adult human spinal cord and BDNF, NT-3, p75, trkB, and trkC in the fetal human spinal cord. The percentage of adul t human DRG cells expressing p75, trkA, trkB, or trkC was 57, 46, 29, and 2 4%, respectively, and that of DRG cells expressing RET, GFR alpha -1, GFR a lpha -2, or GFR alpha -3 was 79, 20, 51, and 32%, respectively. GFR alpha - 2 was expressed selectively in small, GFR alpha -3 principally in small and GFR alpha -1 and RET in both large and small adult human DRG neurons. p75 and trkB were expressed by a wide range of DRG neurons while trkA was expre ssed in most small diameter and trkC primarily in large DRG neurons. Fetal DRG cells were positive for the same probes as adult DRG cells except for N T-3, which was only found in fetal DRG cells. Messenger RNA species only ex pressed at detectable levels in fetal but not adult spinal cord tissues inc luded GDNF, GFR alpha -2, NT-3, and p75. Notably, GFR alpha -2, which is ex pressed in the adult rat spinal cord, was not found in the adult human spin al cord. J. Comp. Neurol. 440:204-217, 2001. (C) 2001 Wiley-Liss, Inc.