Ex vivo effects of bisphenol A or zearalenone on the prepubertal rat testis.

Bisphenol A (BPA) and zearalenone (ZEA) are two widespread xenoestrogens involved in male reproductive disorders. Few studies investigated the effects of these compounds on the prepubertal testis, which is highly sensitive to endocrine disruptors such as xenoestrogens. An ex vivo approach was performed to evaluate the effects of BPA or ZEA (10-11, 10-9, 10-6 M) on the testes of 20 and 25 dpp rats. To investigate the involvement of classical nuclear ER-mediated estrogen signaling in these effects, pre-incubation with an antagonist (ICI 182.780 10-6 M) was performed. BPA and ZEA have similar effects on spermatogenesis- and steroidogenesis-related endpoints in the immature testis, but our study highlights different age-dependent patterns of sensitivity to each compound during the prepubertal period. Moreover, our results indicate that the effects of BPA are likely to be induced by nuclear ER, whereas those of ZEA appear to involve other mechanisms.

Deoxynivalenol enhances estrogen receptor alpha-induced signaling by ligand-independent transactivation.

Deoxynivalenol (DON), which is one of the prevalent mycotoxins in food and feeds, exerts adverse effects on animal and human health. These effects are mainly associated with its ribotoxic properties, although few studies suggest the involvement of other mechanisms of action. To assess the ability of DON to disrupt estrogen signaling, we conducted an in vitro study using MCF-7 and MDA-MB-231 cells. After 72h, DON reduced cell viability in both cell lines, thus highlighting its well-known cytotoxic effect. However, after 6h, DON increased the expression of estrogen-responsive genes, hence demonstrating the stimulation of estrogen signaling by this mycotoxin after a short-term exposure. This effect was partially reversed by siRNA-mediated silencing of ERα expression and by 4-hydroxytamoxifen (ERα antagonist), but neither by G36 (GPER antagonist) nor by the siRNA-mediated silencing of PPARγ2 expression. Moreover, DON exposure induced an increase in the level of ERα phosphorylation at serine 167. Furthermore, when combined with zearalenone (a naturally co-occurring mycotoxin recognized as an endocrine disruptor), DON increased the expression of estrogen-responsive genes to a greater extent than each individual compound taken separately. Taken together, our results suggest, for the first time, that DON can disrupt estrogen signaling through the ligand-independent activation of ERα.

["Sunshine at school": a network for training on sun exposure. Assessment of knowledge among 683 children]. / Le soleil à l'école: réseau d'éducation à l'exposition solaire. Evaluation des connaissances chez 683 enfants de CM1 et CM2.

INTRODUCTION: The protection of children from sun exposure appears inadequate. We assessed the knowledge of pre-teenagers, before and after they attended a training session on sun exposure. This investigation was carried out in Orléans and in 5 surrounding cities, from September 2000 to April 2002. MATERIAL AND METHODS: A didactic slide show on sun exposure and photoprotection was presented to 683 children in grade 4 and 5 by a nurse and a dermatologist during 30 informative sessions. The children filled in questionnaires at each training session and then one month later. The questionnaires contained 10 closed questions involving 32 cognitive and behavioral items. RESULTS: Forty-five percent of the children claimed that they were exposed to the sun more than one hour a day during holidays, 14 p. 100 more than 3 hours a day; 26 p. 100 declared they had never been sunburnt; 46 p. 100 said they had been less than 5 times, 15 p. 100 from 5 to 10 times and 12 p. 100 more than 10 times; 74 p. 100 of the children claimed they enjoyed getting sun-tanned; 80 p. 100 knew that sun exposure could lead to serious diseases, while 73 p. 100 realized that contracting sunburns during childhood increases the risk of subsequent skin cancers; 89 p. 100 knew of the necessity of sun-screen use prior to exposure, 94 p. 100 knew that they help to protect the skin whereas 78 p. 100 knew it must be applied on a regular basis; 77 p. 100 of the children had been informed of the importance of sun protection factor; 92 p. 100 of them were aware of the relevance of a cap and sunglasses for protection from the sun, whereas only 45 p. 100 knew of the need for a tee-shirt. DISCUSSION: Our study showed that children are generally aware of the dangers of sun exposure. This might be the result of previously initiated information and prevention campaigns on skin cancers. This study suggests the efficiency of such projects, and the lasting effects of the information received within one month. However, large numbers of children are still overexposed and subsequently suffer from traumas. The appeal of sun embellishment appears to go back to childhood, and should be taken into account from the early stages of childhood in future preventive actions. An efficient policy of education on sun exposure - including teaching tools relevant to each age--still has to be developed.