Proceedings of The Physiological Society
University of Manchester (2010) Proc Physiol Soc 19, PC250
Expression and distribution of urotensin II and its receptor in the developing rat kidney
A. West1, E. Forty1, N. Ashton1
1. Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom.
The vasoactive peptide urotensin II (UII) is associated with cardiovascular and renal disease in man. Recently we have shown that endogenous UII acts on the renal tubule to influence sodium and potassium transport in the adult rat . Protein and mRNA expression of UII and its receptor (UT) are prominent in the renal medulla in the adult . As the ability to reabsorb sodium and water develops in utero and continues in the first few weeks post-natally, the aim of this preliminary study was to investigate the expression and distribution of UII and UT protein during renal development in the rat. Metanephroi from Sprague-Dawley rats at embryonic stage 16 (E16), 19 (E19) or 21 (E21), and kidneys from postnatal day 1 (PN1), 7 (PN7), 10 (PN10) or 4 weeks of age were removed and fixed for wax embedding. Sections of paraffin-embedded kidney 5μm thick were immunostained with either polyclonal rabbit anti-flounder UII antibody  (1:200 dilution) or polyclonal rabbit anti-rat UT antibody (1:100 dilution, Santa Cruz Biotechnology) and developed with 3,3-diaminobenzidine. Negative controls omitting primary antibody were included. Immunostaining of UII peptide is faint, diffuse and ubiquitous in metanephroi at E16, with little change in distribution or intensity of expression through to E19 and E21. By PN1 UII immunostaining in the cortex and nephrogenic zones has reduced in intensity, with positive staining concentrating in the collecting system. The intensity of the diffuse UII staining increases by PN7 and PN10, peaking at 4 week of age with prominent expression within collecting tubules of the medulla and papilla. UT expression first appears at E19 with highly intense and specific staining in the future collecting system (Figure 1). UT protein is localised to the cytoplasm within cells, however, UT is not present in every cell within a collecting tubule (Figure 1). This pattern of UT immunolocalisation continues at E21, but is restricted to fewer cells. UT expression is greatly reduced by PN1, however, when present in collecting tubules UT is located in every cell in a diffuse but punctate pattern. This UT distribution continues into PN7 and PN10 and by 4 weeks of age UT expression has extended from the papilla to the inner and outer medullary collecting system. These data show that UII peptide is expressed ubiquitously in the kidney from early in development, in contrast with UT expression which first appears at E19 and is limited to the collecting tubules. UT expression peaks at E19, decreasing in intensity with age, suggesting a role for the receptor in nephrogenesis. In conclusion results indicate that UII system is expressed in the kidney during pre- and post-natal development, suggesting that this peptide system may have a role in the development of urine concentrating ability.
Where applicable, experiments conform with Society ethical requirements