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This Article Full Text Full Text (PDF) All Versions of this Article: 296/4/E731    most recent 90795.2008v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Cabilla, J. P. Articles by Duvilanski, B. H. Search for Related Content PubMed PubMed Citation Articles by Cabilla, J. P. Articles by Duvilanski, B. H.

Nitric oxide sensitive-guanylyl cyclase subunit expression changes during estrous cycle in anterior pituitary glands

Departamento de Química Biológica, Instituto de Química y Fisicoquímica Biológicas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina

Submitted 6 September 2008 ; accepted in final form 7 January 2009

17β-Estradiol (E₂) exerts inhibitory actions on the nitric oxide pathway in rat adult pituitary glands. Previously, we reported that in vivo E₂ acute treatment had opposite effects on soluble guanylyl cyclase (sGC) subunits, increasing ₁- and decreasing β₁-subunit protein and mRNA expression and decreasing sGC activity in immature rats. Here we studied the E₂ effect on sGC protein and mRNA expression in anterior pituitary gland from adult female rats to address whether the maturation of the hypothalamus-pituitary axis influences its effects and to corroborate whether these effects occur in physiological conditions such as during estrous cycle. E₂ administration causes the same effect on sGC as seen in immature rats, and these effects are estrogen receptor dependent. These results suggest that E₂ is the main effector of these changes. Since the sGC -subunit increases while the sGC activity decreases, we studied if other less active isoforms of the sGC -subunit are expressed. Here we show for the first time that sGC₂ and sGC₂ inhibitory (_2i) isoforms are expressed in this gland, but only sGC_2i mRNA increased after E₂ acute treatment. Finally, to test whether E₂ effects take place under a physiological condition, sGC subunit expression was monitored over estrous cycle. sGC₁, -β₁, and -_2i fluctuate along estrous cycle, and these changes are directly related with E₂ level fluctuations rather than to NO level variations. These findings show that E₂ physiologically regulates sGC expression and highlight a novel mechanism by which E₂ downregulates sGC activity in rat anterior pituitary gland.

estrogen; soluble guanylyl cyclase; inhibitory subunit