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Focal expression of insulin-like growth factor I in rat kidney collecting duct.

1988; Rockefeller University Press; Volume: 107; Issue: 2 Linguagem: Inglês

10.1083/jcb.107.2.811

1540-8140

J. D. Bortz, Peter Rotwein, D. L. DeVol, Peter J. Bechtel, V. A. Hansen, Marc R. Hammerman,

Growth Hormone and Insulin-like Growth Factors

To address the question of insulin-like growth factor (IGF) I localization and synthesis in kidney, we used two complementary experimental approaches: immunohistochemistry of fixed paraffin-embedded rat kidney sections; and measurement of IGF I mRNA in isolated components of the rat nephron, using a highly sensitive and specific solution hybridization assay. Immunostainable IGF I was localized exclusively to principal cells of cortical and medullary collecting ducts. Administration of growth hormone to hypophysectomized rats for 8 d resulted in enhanced immunohistochemical staining of IGF I within collecting ducts, but no detectable IGF I in other portions of the nephron. The abundance of IGF I mRNA was 7-12-fold higher in isolated papillary collecting ducts than in proximal tubules or glomeruli, and was enriched 10-fold compared with whole kidney. Our data demonstrate colocalization of IGF I and IGF I mRNA in the collecting duct, consistent with focal expression of the IGF I gene at this site.