Glial cell line-derived neurotrophic factor-like immunoreactivity in humantrigeminal ganglion and nucleus

Glial cell Line-derived neurotrophic factor (GDNF) is shown by immunohistoc hemistry in human trigeminal sensory system from 22 weeks of gestation to a dulthood. In the trigeminal ganglion, a distinct subpopulation of GDNF-posi tive neurones is observed, which amounts to about 15% at early pre-term and adult ages and peaks to around 30% at perinatal ages. Labelled neurones ar e mostly small- and medium-sized. Occasionally, Schwann and satellite cells are stained. GDNF/substance P (SP) and GDNF/calcitonin gene-related peptid e (CGRP) double stained neurones occur at all ages examined, whereas GDNF/t rkA coexistence can be observed in pre- and full-term newborns only. Centra lly, GDNF-immunostained fibers and terminal-like structures are mainly rest ricted to the spinal trigeminal nucleus, where they are codistributed with SP and CGRP. In the subnucleus caudalis, positive neurones can also be obse rved both in the superficial laminae and in the magnocellular part, with hi gher frequency in adults. These results suggest that GDNF may play a functi onal role in human trigeminal primary sensory neurones throughout life and provide indication for its possible involvement in the regulation of pain-r elated neuronal circuits in human trigeminal sensory system. (C) 1999 Elsev ier Science B.V. All rights reserved.