Regulation of Peroxisome Proliferator Activated Receptor‐γ in Rat Pituitary

Peroxisome proliferator activated‐receptor γ (PPARγ) is a member of the nuclear receptor superfamily and, in addition to its relation with obesity and insulin sensitivity, it has recently been localized in human and mice pituitary, indicating a functional significance of PPARγ in adenopituitary tumours. In the present study, we localized the PPARγ mRNA and protein in different cell types of rat pituitary. Moreover, using the real‐time polymerase chain reaction, we assessed the mRNA expression of PPARγ in different physiological and pathological settings known to be associated with alterations in anterior pituitary cell proliferation and/or function. Our experiments have shown that PPARγ mRNA levels were repressed by oestrogen through an oestrogen receptor‐α effect. However, PPARγ protein levels were only modified in males but not in females. On the other hand, PPARγ mRNA expression was increased in dwarf rats in comparison with Lewis rats. Finally, nutritional, thyroid status or pregnancy did not change PPARγ expression. Taken together, we provide new data regarding the regulation of pituitary PPARγ mRNA by hormonal and metabolic status.