Objectives: Intestinal crypt fission peaks during infancy. In human and experimental familial polyposis coli, increased crypt fission is due to activation of Wnt/β-catenin signalling, but the molecular basis of crypt fission during intestinal growth has not been examined. The aim of this project was to investigate whether crypt fission and intestinal growth are affected by experimental blockade of the Wnt/β-catenin signalling pathway.
Methods: Hooded Wistar rats were given either the Wnt inhibitor, dickkopf (30 and 100 ng), daily or vehicle control intraperitoneally from days 11 to 15 and were killed at day 16. Intestinal morphometry was used to measure villous area, crypt area, percentage of crypt fission, and crypt mitotic count. Intestinal stem cells were assessed by expression of real time-polymerase chain reaction for Lgr5 (a stem cell marker), and the number of β-catenin–expressing crypts by immunostaining was determined after 100-ng dickkopf treatment.
Results: Dickkopf at 30 and 100 ng/day reduced villous area to 71% (P = 0.013) and 29% (P < 0.0001), crypt area to 42% (P = 0.0026) and 30% (P = 0.0067), and crypt fission to 51% (P = 0.006) and 29% (P < 0.0001), respectively, of control values. Mitotic count per crypt did not change. Lgr5 RNA expression and the number of β-catenin–expressing crypts decreased in dickkopf-treated animals.
Conclusions: We conclude that intestinal crypt fission during infancy is mediated by Wnt signalling. It is possible that local treatment with Wnt agonists could be used to increase intestinal growth.
*School of Animal and Veterinary Sciences, Roseworthy Campus, University of Adelaide
‡Department of Gastroenterology and Hepatology, The Queen Elizabeth Hospital, Woodville South
§Discipline of Medicine, School of Medicine, University of Adelaide
||Women's and Children's Health Research Institute, North Adelaide, South Australia, Australia.
Address correspondence and reprint requests to Ms Jane K. Fauser, University of Adelaide, School of Animal and Veterinary Sciences, Roseworthy Campus, 5371 South Australia, Australia (e-mail: email@example.com).
Received 5 August, 2011
Accepted 14 December, 2011
The present study was supported by the National Health and Medical Research Council of Australia 508024 project grant to I.A.P. and A.G.C. Parts of this work were submitted by J.K.F. as a thesis in support for a PhD to the University of Adelaide. G.S.H. was supported by the Sally Birch Cancer Council Australia Senior Research Fellowship in Cancer Control.
The authors report no conflicts of interest.