title: Pituitary Aromatase P450 May Be Involved in Maintenance of the Population of Luteinizing Hormone-Positive Pituitary Cells in Mice.
abstract: As aromatase P450 is located in several pituitary cells, testosterone can be transformed into 17β-estradiol in the gland by the enzyme. The possible role of this transformation in pituitary function remains to be elucidated, but some evidence suggests a physiological and pathophysiological role for pituitary aromatase. To determine its relevance in the modulation of pituitary function, mainly associated with reproduction, luteinizing hormone (LH)-positive cells in the hypophysis of female and male aromatase knockout (ArKO) mice were studied. In all LH-positive cells, significant increases in the cellular (p < 0.01) and nuclear (p < 0.05) areas were found in the ArKO mice compared to the wild-type mice. In the ArKO mice, LH-positive cells were more abundant (p < 0.01); they were characterized by a stronger cytoplasmic reaction and the cells were more polygonal and exhibited more short, thick cytoplasmic prolongations than those in the wild-type mice. Moreover, LH-positive cells showed a greater proliferation rate in the ArKO mice compared to the wild-type mice (p < 0.01). These findings suggest that the local production of estradiol mediated by pituitary aromatase is necessary for the regulation of LH-positive gonadotropic cells, exerting an autoparacrine inhibitory regulation. These results could underlie the higher pituitary aromatase expression observed in male versus female mice. Similar effects were found in ArKO male and female mice, suggesting that in both sexes the effects of estrogens on maintenance of the LH-positive pituitary cell population could be related to the local aromatization of testosterone to estradiol inside the hypophysis. Therefore, aromatase could modulate pituitary LH-positive cells in males through local estradiol synthesis.
authors.affiliation: Department of Human Anatomy and Histology, Faculty of Medicine, University of Salamanca, Salamanca, Spain.
authors.forename: Jose
authors.initials: J
authors.lastname: Carretero
authors.forename: Francisco
authors.initials: F
authors.lastname: López
authors.forename: Leonardo
authors.initials: L
authors.lastname: Catalano-Iniesta
authors.forename: Virginia
authors.initials: V
authors.lastname: Sanchez-Robledo
authors.forename: Maria Jose
authors.initials: MJ
authors.lastname: Garcia-Barrado
authors.forename: Maria Carmen
authors.initials: MC
authors.lastname: Iglesias-Osma
authors.forename: Marta
authors.initials: M
authors.lastname: Carretero-Hernandez
authors.forename: Enrique J
authors.initials: EJ
authors.lastname: Blanco
authors.forename: Deborah Jane
authors.initials: DJ
authors.lastname: Burks
mesh_terms: D000818:Animals; D001141:Aromatase / Q000378:metabolism*; D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism; D049109:Cell Proliferation; D005260:Female; D007986:Luteinizing Hormone / Q000378:metabolism*; D008297:Male; D008810:Mice, Inbred C57BL; D008954:Models, Biological; D010902:Pituitary Gland / Q000166:cytology* / Q000201:enzymology*; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism
chemical_list: D018809:Proliferating Cell Nuclear Antigen; D007986:Luteinizing Hormone; D001141:Aromatase