MITOTIC ACTIVITY OF LYMPHOCYTES IN PREPUBERTAL RATS EXPOSED TO LOW DOSES OF DDT

Low-dose developmental exposure to DDT results in inhibited mitotic activity of thymic lymphocytes in prepubertal rats. Decreased number of proliferating cells in deeper layers of the cortex and in the medulla, not subcapsular lymphoblasts, contributes to lowered proliferation rate.

Immunohistochemical study of the effects of heavy metals on the intestinal mucosa in prepubertal rats

Introduction. Numerous studies of pathological effects of heavy metals were mostly carried out on adult experimental animals. The aim of this work was to evaluate the markers of proliferation and apoptosis in the mucosa of the small intestine in Wistar prepubertal rats under isolated and combined exposure to cadmium and lead at subtoxic doses. Materials and methods. We used immunohistochemistry to study Ki67 and p53 expression in the mucosa of the small intestine in 40 male Wistar prepubertal rats aged 4 weeks, the animals having been exposed to isolated or combined per os subtoxic cadmium and/or lead doses for 21 days. Results. In paraffin sections, we observed a significant increase in Ki67 expression in the epithelium of the small intestine in the group of combined exposure to heavy metals compared to Ki67 expression in the control group and other groups with isolated exposure to cadmium or lead. p53 expression in the epithelium of the small intestinal crypts and villi grew in the experimental groups compared to that in the control group, the highest indices being in the combined exposure group. The number of epithelial goblet cells significantly decreased in all experimental groups compared to that in the control group, the smallest number of goblet cells being observed in isolated exposure to lead compared to that in all other groups. Conclusion. Heavy toxic metals cadmium and lead induced the proliferative activity of epithelial cells in the small intestinal mucosa combined with an increased p53 expression and reduced number of epithelial goblet cells. Keywords: small intestinal mucosa, prepubertal rats, cadmium, lead, proliferation, apoptosis, immunohis-tochemistry