Evidence for increased GDNF signaling in aged sensory and motor neurons

SEVERAL lines of evidence suggest that attenuated neurotrophin signaling ma y account for some of the aging-related phenotypic changes observed in moto r and sensory neurons. Glial-derived neurotrophic factor (GDNF) signals thr ough the GFR alpha-1-RET receptor complex and has trophic effects on both p rimary sensory neurons and, in particular, motoneurons. In this study we pr ovide evidence using RT-PCR that GDNF, but not neurturin, is strongly up-re gulated in target muscles (800%) and to a lesser extent also in peripheral supportive tissues. Results here, and in an earlier study, show that the up -regulation of GDNF in target and supportive tissues parallels an increased neuronal expression of the cognate receptors. Increased GDNF signaling may explain some of the phenotypic characteristics of aging sensory and motone urons. NeuroReport 10:1529-1535 (C) 1999 Lippincott Williams & Wilkins.