AIM： TO investigate the role of a-fetoprotein （AFP）, a cancer-associated fetal glycoprotein, in glucocorticoidinduced precocious maturation in rat colon. METHODS： Colons from suckling Sprague-Dawley rats were used...AIM： TO investigate the role of a-fetoprotein （AFP）, a cancer-associated fetal glycoprotein, in glucocorticoidinduced 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 indicesof colon maturation. Expression levels of AFP in colons were detected by reverse transcriptase polymerase chain reaction and Western blotting. To identify the cellular lo- calization of AFP in developing rat colons, double-immu- nofluorescent 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 ani- mals （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 ex- pression 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 hypercorti- coidism were blocked by mifepristone. Both had positive staining for AFP or vimentin, and overlapped in mesen- chymal 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.展开更多
文摘AIM： TO investigate the role of a-fetoprotein （AFP）, a cancer-associated fetal glycoprotein, in glucocorticoidinduced 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 indicesof colon maturation. Expression levels of AFP in colons were detected by reverse transcriptase polymerase chain reaction and Western blotting. To identify the cellular lo- calization of AFP in developing rat colons, double-immu- nofluorescent 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 ani- mals （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 ex- pression 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 hypercorti- coidism were blocked by mifepristone. Both had positive staining for AFP or vimentin, and overlapped in mesen- chymal 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.
