title: Exposure to phosphodiesterase type 5 inhibitors stimulates aromatase expression in human adipocytes in vitro.
abstract: BACKGROUND
  Prolonged tadalafil administration in men with erectile dysfunction is associated with increased testosterone (T): estradiol (E(2)) ratio mainly related to reduction of E(2) levels.
  
  
  OBJECTIVE
  To investigate the presence of phosphodiesterase type 5 (PDE5) isoenzyme in primary human visceral adipocytes and whether different PDE5 inhibitors (PDE5i) could directly modulate aromatase (ARO) expression in differentiated human visceral adipocytes in culture.
  
  
  METHODS
  PDE5 mRNA and protein expression in primary human visceral adipocytes as well as mRNA and protein expression of ARO, with functional activity after selective PDE5 blockade by tadalafil and sildenafil.
  
  
  METHODS
  Purified primary human visceral pre-adipocytes were differentiated ex vivo and were exposed to tadalafil or sildenafil (1 µM) for different intervals of time (6-12-24-96 hours). ARO mRNA content and expression were measured by Western Blot and quantitative reverse transcription-polymerase chain reaction (qRT-PCR), respectively. T and E(2) in supernatants were measured by ELISA also in the presence of letrozole.
  
  
  RESULTS
  Differentiated adipocytes were found to express detectable levels of PDE5 transcripts. Acute exposure (6 hours) to both PDE5i tadalafil and sildenafil increased ARO mRNA expression by 4.7- and 2.8-fold, respectively (P < 0.001). ARO mRNA and protein levels were increased by the treatment with PDE5i in a time- and dose-dependent manner. Such effect was mimicked by 8-bromo-cGMP but was lost after 24 and 96 hours; differently, the PDE3B specific inhibitor milrinone (1 µM), displayed no effect. Accordingly, long-term exposure (24 and 96 hours) to PDE5i caused a significant increase in E(2) concentrations in the supernatant (1.7 and 2 fold, respectively; P < 0.001), with a parallel reduction of T (15% and 30%, respectively; P < 0.001). Such effect was reversed by the co-incubation with the specific ARO-inhibitor letrozole.
  
  
  CONCLUSIONS
  Our results demonstrate that PDE5 is expressed in human visceral adipocytes and that acute exposure to PDE5i selectively stimulates ARO expression, which is related to a specific PDE5 blockade. We speculate that modulation of ARO activity by PDE5i could be one of the mechanisms responsible, at least in part, for the beneficial effects of PDE5i on endothelial and metabolic functions.
authors.affiliation: Department of Experimental Medicine, Section of Medical Pathophysiology-Sapienza University of Rome, Rome, Italy. antonio.aversa@uniroma1.it
authors.forename: Antonio
authors.initials: A
authors.lastname: Aversa
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Caprio
authors.forename: Antonella
authors.initials: A
authors.lastname: Antelmi
authors.forename: Andrea
authors.initials: A
authors.lastname: Armani
authors.forename: Marina
authors.initials: M
authors.lastname: Brama
authors.forename: Emanuela A
authors.initials: EA
authors.lastname: Greco
authors.forename: Davide
authors.initials: D
authors.lastname: Francomano
authors.forename: Matilde
authors.initials: M
authors.lastname: Calanchini
authors.forename: Giovanni
authors.initials: G
authors.lastname: Spera
authors.forename: Luigi
authors.initials: L
authors.lastname: Di Luigi
authors.forename: Giuseppe M C
authors.initials: GM
authors.lastname: Rosano
authors.forename: Andrea
authors.initials: A
authors.lastname: Lenzi
authors.forename: Silvia
authors.initials: S
authors.lastname: Migliaccio
authors.forename: Andrea
authors.initials: A
authors.lastname: Fabbri
mesh_terms: D017667:Adipocytes / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D001141:Aromatase / Q000096:biosynthesis*; D015153:Blotting, Western; D002243:Carbolines / Q000494:pharmacology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D058986:Phosphodiesterase 5 Inhibitors / Q000494:pharmacology*; D010879:Piperazines / Q000494:pharmacology; D011687:Purines / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000068677:Sildenafil Citrate; D013450:Sulfones / Q000494:pharmacology; D000068581:Tadalafil
chemical_list: D002243:Carbolines; D058986:Phosphodiesterase 5 Inhibitors; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D000068581:Tadalafil; D000068677:Sildenafil Citrate; D001141:Aromatase