EXPRESSION AND LOCALIZATION OF GDNF IN DEVELOPING AND ADULT ADRENAL CHROMAFFIN CELLS

Glial cell line-derived neurotrophic factor (GDNF) is a widely distrib uted member of the transforming growth factor-beta superfamily and a p otent neurotrophic molecule for several neuron populations in the peri pheral and central nervous system. We show here that adrenal medullary chromaffin cells synthesize GDNF mRNA and contain immunoreactive GDNF protein. GDNF immunoreactivity can be found as early as embryonic day 16 in chromaffin progenitor cells of the rat adrenal gland and become s more prominent with age. Most of the chromaffin cells within the adu lt rat adrenal medulla are GDNF immunoreactive, including both the nor adrenergic and adrenergic subpopulations. The functions of adrenal med ullary GDNF are still enigmatic but may include both auto/paracrine ro les and retrograde trophic support of preganglionic neurons in the spi nal cord or of sensory neurons that innervate chromaffin cells.