Effects of Neonatal Administration of Diethylstilbestrol on Aberrant Crypt Foci Induced by 7,12-Dimethylbenz[α]anthracene in Rats

Gastrointestinal carcinoma is affected environmental factors, however, it remains to be determined whether neonatal administration of an estrogenic endocrine disruptor, such as diethylstilbestrol (DES), affects gastrointestinal carcinogenesis. The effects of neonatally administered DES on gastrointestinal tumorigenesis induced by 7,12-dimethylbenz[α]anthracene (DMBA) were investigated in male and female rats. Male and female rats in group I were daily administered oil alone from 0-14 days after birth. Male and female rats in groups II and III were daily administered DES at 1 and 10 μg/rat, respectively. The administration periods of DES in subgroups a (IIa and IIIa), b (IIb and IIIb) and c (IIc and IIIc) were from 0-14, 0-5 and 6-14 days after birth, respectively. At 28, 42 and 56 days after birth, all male rats were given 10 mg of DMBA. At 50 days after birth, all female rats were given 10 mg of DMBA. In the digestive tracts of male rats, forestomach masses (FMs) in all groups (13-58%), small intestine masses in group IIIa (17%), and colon masses (CMs) in groups IIIa (8%) and IIIb (33%) were observed, although there were no significant changes in the incidence and number. In the digestive tracts of female rats, FMs in groups I (10%), IIa (13%), IIb (33%), IIc (25%) and IIIc (33%), CMs in groups IIa (6%) and IIIa (6%) were seen, although there were no significant changes in the incidence. Aberrant crypt foci (ACF) in the colon and rectum were seen in all male and female rats. The neonatal administration of DES in male rats increased the number of ACF while that in female rats did not. These results suggest that neonatal administration of DES may affect male colorectal carcinogenesis.