Submitted on May 9, 2005
Accepted on January 26, 2006
Localized Accumulation of Angiotensin II and Production of Angiotensin-(1-7) in Rat Luteal Cells, and Effects on Steroidogenesis
John R Pepperell1*, Gabor Nemeth2, Yuji Yamada2, Frederick Naftolin2, and Maricruz Merino3
1 Department of Obstetrics and Gynecology, Yale University Medical School, New Haven, CT, USA; Department of Pathology, Brown University Medical School, Providence, RI, USA
2 Department of Obstetrics and Gynecology, Yale University Medical School, New Haven, CT, USA
3 Department of Pediatrics, Brown University Medical School, Providence, RI, USA
* To whom correspondence should be addressed. E-mail: jpeppere{at}wihri.org.
These studies aim to investigate subcellular distribution of angiotensin II (Ang II) in rat luteal cells, identify other bioactive angiotensin peptides, and investigate a role for angiotensin peptides in luteal steroidogenesis. Confocal microscopy showed Ang II distributed within the cytoplasm, and nuclei of luteal cells. HPLC analysis showed peaks that eluted with the same retention times as Ang-(1-7), Ang II and Ang III. Their relative concentrations were: Ang II 
Ang-(1-7) >> Ang III, and accumulation was modulated by quinapril, an inhibitor of the angiotensin converting enzyme (ACE), Z-proprolinal (ZPP) an inhibitor of prolyl endopeptidase (PEP), and parachloromercurylsulfonic acid (PCMS) a sulfhydryl protease inhibitor. Phenylmethylsulfonyl fluoride (PMSF) a serine protease inhibitor did not affect peptide accumulation.
Quinapril, ZPP, PCMS, PMSF, losartan, the angiotensin receptor type 1 (AT1), and PD123319, the AT2, receptor antagonists were used in progesterone production studies. ZPP significantly reduced LH-dependent progesterone production (p < 0.05). Quinapril plus ZPP had a greater inhibitory effect on LH-stimulated progesterone than either inhibitor alone, but this was not reversed by exogenous Ang II or Ang-(1-7). Both PCMS and PMSF acutely blocked LH-stimulated progesterone, and PCMS blocked LH-sensitive cyclic AMP accumulation. Losartan inhibited progesterone production in permeabilized, but not intact luteal cells that was reversed by Ang II. PD123319 had no significant effect on luteal progesterone production in either intact or permeabilized cells. These data suggest that steroidogenesis may be modulated by angiotensin peptides that act in part through intracellular AT1 receptors.
