Effect of Ovarian Steroids on Colonic Epithelial Cell Proliferation and Apoptosis in Rats

Abstract

The aim of this study was to investigate the effects of steroid hormones on proliferation and apoptosis in the colon crypt epithelium. The research was conducted on adult ovariectomized (Ovx) rats (Sprague Dawley). Ovx rats were injected for 15 days with 0.2 ml of sesame oil (control; C), or 17β-oestradiol (10 μg/d; E), or progesterone (2 mg/d; P), or E + P. Proliferative activity in the colon was assessed by using proliferating cell nuclear antigen (PCNA) antibody. The proliferation index (PI), the number of PCNA positive cells divided by the total number of cells counted in the crypt column multiplied by 100, was calculated. PI was lower in the hormonetreated groups, especially in group P compared to that in group C. The apoptotic index (AI), the mean number of apoptotic cells, was detected by active caspase 3 immunoreactivity per crypt in the colon. AI was lower in the colon crypt epithelium of group E than that of the other groups. However, AI in the colon crypt epithelium in groups P and E + P was higher than that of both group E and group C. In addition, the colon crypt size (the number of epithelial cells lining one side of 10 well-oriented, longitudinally cut crypts) was considerably lower in group E than that of the other groups. In conclusion, we showed that the decrease of AI in group E was balanced by progesterone; the decrease of PI in group P was also depressed by oestrogen.