Original Article
Copyright ©2011 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Jun 28, 2011; 17(24): 2933-2940
Published online Jun 28, 2011. doi: 10.3748/wjg.v17.i24.2933
α-fetoprotein involvement during glucocorticoid-induced precocious maturation in rat colon
Min Chen, Peng Sun, Xiao-Yan Liu, Dan Dong, Jun Du, Luo Gu, Ying-Bin Ge
Min Chen, Lian Yun Gang Higher Vocational Technical College of Traditional Chinese Medicine, Lianyungang 222006, Jiangsu Province, China
Peng Sun, Dan Dong, Jun Du, Luo Gu, Ying-Bin Ge, Department of Physiology, Nanjing Medical University, Nanjing 210029, Jiangsu Province, China
Xiao-Yan Liu, The Laboratory Center for Basic Medical Sciences, Nanjing Medical University, Nanjing 210029, Jiangsu Province, China
Author contributions: Chen M and Sun P performed the animal experiment, RT-PCR and immunofluorescent staining and wrote the paper; Liu XY performed part of RT-PCR and immunofluorescent staining; Dong D and Du J carried out Western blotting and statistical analysis; Ge YB contributed to the the paper writing and experimental design; Gu L and Ge YB contributed equally to this work.
Correspondence to: Ying-Bin Ge, MD, PhD, Department of Physiology, Nanjing Medical University, Nanjing 210029, Jiangsu Province, China. ybge@njmu.edu.cn
Telephone: +86-25-86862022 Fax: +86-25-86862022
Received: July 1, 2010
Revised: February 15, 2011
Accepted: February 22, 2011
Published online: June 28, 2011
Abstract

AIM: To investigate the role of α-fetoprotein (AFP), a cancer-associated fetal glycoprotein, in glucocorticoid-induced precocious maturation in rat colon.

METHODS: Colons from suckling Sprague-Dawley rats were used in this study. Corticosterone acetate at a dose of 100 μg/g body weight was given to normal pups on days 7, 9 and 11 after birth to induce hypercorticoidism. Control animals were injected with identical volumes of normal saline. Some rats receiving corticosterone 7 d after birth were also treated with mifepristone (RU38486), a glucocorticoid cytoplasm receptor antagonist to investigate the effects of glucocorticoids (GCs). The morphological changes of the crypt depth and villous height of the villous zone in colon were observed as indices of colon maturation. Expression levels of AFP in colons were detected by reverse transcriptase polymerase chain reaction and Western blotting. To identify the cellular localization of AFP in developing rat colons, double-immunofluorescent staining was performed using antibodies to specific mesenchymal cell marker and AFP.

RESULTS: Corticosterone increased the crypt depth and villous height in the colon of 8- and 10-d-old rats with hypercorticoidism compared with that in the control animals (120% in 8-d-old rats and 118% in 10-d-old rats in villous height, P = 0.021; 145% in 8-d-old rats and 124% in 10-d-old rats in crypt depth, P = 0.017). These increases were accompanied by an increase of AFP expression in both mRNA and protein (2.5-folds in 8-d-old and 2.5-folds in 10-d-old rats higher than in control animals, P = 0.035; 1.8-folds in 8-d-old and 1.3-folds in 10-d-old rats higher than in control animals, P = 0.023). Increased crypt depth and villous height and increased expression of AFP in the colon of rats with hypercorticoidism were blocked by mifepristone. Both had positive staining for AFP or vimentin, and overlapped in mesenchymal cells at each tested colon.

CONCLUSION: GCs promote the development of rat colon. AFP appears to be involved, in part, in mediating the effects of GCs in the developmental colon.

Keywords: Glucocorticoids, α-fetoprotein, Precocious maturation, Colon, Rat