Neurotensin is localized to paracrine cells in the urinary bladder of the turtle, Chrysemys picta

Abstract

Urinary bladder from the painted turtle, Chrysemys picta, contains a substantial population of endocrine/paracrine cells scattered through the mucosal epithelium which immunostains using antisera directed toward mammalian neurotensin (NT). Radioimmunoassay of 0.1 N HCl extracts of Chrysemys bladder indicated an immunoreactive NT (iNT) concentration of 161 ± 39 pmol/g tissue ( n = 9), an amount lower but comparable in magnitude to that found in mucosal scrapings of the intestine (926 ± 125 pmol/g, n = 9). Bladder and intestinal iNT were indistinguishable during chromatography on Sephadex G-25 and HPLC on μ-Bondapak C 18 where they eluted at the same position as avian NT. Similar results were obtained by immunocytochemistry and radioimmunoassay of urinary bladders from Pseudemys scripta scripta, P. scripta elegans, and P. floridana, three emydid species closely related to C. picta, but not from Sternotherus odoratus and Trionyx spinifer asper, representatives of the families Kinosternidae and Trionychidae, respectively, although positive results were obtained with intestinal preparations from these species. NT cells were not seen in urinary bladder from Rana pipiens, Bufo marinus, Necturus maculosus, or Anolis carolinensis. Thus, the presence of NT-containing cells in urinary bladder is not common among subavian vertebrates and may even be restricted to the Emydidae family of chelonians.