Glial cell line-derived neurotrophic factor in the rat pituitary gland

The presence of glial cell line-derived neurotrophic factor (GDNF) is descr ibed within specific regions of the adult rat pituitary gland. Immune stain ing methods revealed a small number of GDNF-immunopositive cells in the ant erior lobe, and in areas of the neural lobe, while no immunoreactive endocr ine cells were observed in the intermediate lobe. In the neural lobe, immun ofluorescence methods were also used to demonstrate that GDNF and glial fib rillary acidic protein (GFAP) are colocalized in the glial cells (pituicyte s) of the neural lobe. GDNF was not co-localized with neurofilament (NF) in nerve fibers of the neural lobe, suggesting that it is not present in axon al fibers. Measurements of GDNF content in separated anterior and neurointe rmediate lobes were also performed, using an enzyme-linked immunoassay (ELI SA). Values for GDNF were slightly higher in the neurointermediate lobe tha n those obtained for the anterior lobe. The presence of GDNF in areas of th e pituitary is discussed in the context of its possible function to support and maintain hypothalamic innervation, as well as a potential autocrine fa ctor within endocrine cells. (C) 2000 Elsevier Science Inc.