At 24 and 48 h, the LGC were fixed for assessment of DNA fragmentation via an in situ immunofluorescence technique. 24 h, compared with controls. The effect of TCDD on E2 was abolished with the addition of A4. TCDD treatment did not alter progesterone accumulation. Apoptosis increased at 24 h with 3.1 microM TCDD, with no apparent effect at 3.1 nM. By 48 h, however, TCDD increased apoptosis in a dose-dependent manner.
Several dioxins are extremely stable compounds and persist for years in the environment.
Exposure to dioxins occurs mainly via the ingestion of contaminated food. The lipophilic character of dioxins prevents their excretion in the urine and causes their accumulation in body fat. The mechanisms of dioxin action are similar to those of a hormone. Dioxins bind to a specific intracellular receptor and the complex acts as a transcription factor that induces the production of a great number of proteins. The carcinogenicity of dioxins is well documented in animal models and has been described in humans after professional and accidental exposures.