Endocrine Abstracts

An increased prevalence of acromegaly and pituitary tumors has recently been observed in high industrial density areas (Cannavò et al. J Endocrinol 2010) or after dioxin exposure (Pesatori et al. Eur J Endocrinol 2008). These data as well as vitro studies on endocrine disruptors (EDs) suggest that environmental pollutants may affect hormonal secretion and pituitary cell proliferation (Blake et al. Proc Soc Exp Biol Med 1997, Wilson et al. Endocrinology 1998, Maruyama et al. Endocr J 1999, Elango et al. Gen Comp Endocrinol 2006, Dang et al. Toxicol Sci 2007, Dang et al. J Reprod Dev 2009, Dang et al. Steroids 2009). The aim of our study was to verify the effect of endocrine disruptors on rat pituitary and human pituitary adenoma proliferative activity.

Methods: Pituitary primary cultures were incubated with 250 pM–1.25 nM phenol or bis-(2-ethylhexyl)-phthalate for 24 and 96 h. Cell viability, apoptosis and proliferation were assessed by ATP lite (Perkin Elmer, USA), MTT assay (Sigma), Caspases 3–7 (Promega), and 5-bromo-2′-deoxyuridine labeling (BrdU-labeling; Roche).

Results: In rat pituitary primary cultures, ATP cell content was reduced by phenol (100±2% vs 75.3±3.4%, P<0.0001 control vs treatment) and bis-(2-ethylhexyl)-phthalate (100±2% vs 83.2±3.1%, P<0.0001) at 24 h. After 96 h, ATP was clearly increased by phenol (100±2% vs 123.9±7%, P<0.05, control vs treatment), less by bis-(2-ethylhexyl)-phthalate (100±2% vs 111.4±13%, NS). BrdU-labeling and MTT were also increased at the latter timepoint (BrdU-labeling: 100±12% vs 136±12%, P<0.05 and 100±12% vs 137±8%, P<0.05, for phenol and bis-(2-ethylhexyl)-phthalate respectively; MTT: 100±4% vs 118±5%, P<0.05 and 100±4% vs 123±10%, P<0.05, for phenol and bis-(2-ethylhexyl)-phthalate respectively). No changes in caspase activation were observed at 24 or 96 h. In two human GH-secreting primary adenomas, ATP content was increased by 40 and 100%, respectively, after 24 h incubation with 650 pM phenol.

Conclusions: Our findings show than phenol and bis-(2-ethylhexyl)-phthalate initially reduce then increase pituitary cell energy content; further, long-term incubation with EDs is associated with increased cell proliferation. This study indicates that both normal and adenomatous pituitary cell proliferation is modulated by endocrine disruptors, thus supporting the role of pollutants in pituitary adenoma aetiology.

Disclosure: This study was funded by the Italian Ministry for Teaching, University and Research (PRIN 2010–2011 #2010TYCL9B_004).