Nitric oxide synthases and tubal ectopic pregnancies induced by Chlamydia infection: Basic and clinical insights

Ruijin Shao, Sean X. Zhang, Birgitta Weijdegård, Shien Zou, Emil Egecioglu, Anders Norström, Mats Brännström, Håkan Billig

Research output: Contribution to journalReview articlepeer-review

17 Scopus citations


Human ectopic pregnancy (EP) remains a common cause of pregnancy-related first trimester death. Nitric oxide (NO) is synthesized from L-arginine by three NO synthases (NOS) in different tissues, including the Fallopian tube. Studies of knockout mouse models have improved our understanding of the function of NOS isoforms in reproduction, but their roles and specific mechanisms in infection-induced tubal dysfunction have not been fully elucidated. Here, we provide an overview of the expression, regulation and possible function of NOS isoforms in the Fallopian tube, highlighting the effects of infection-induced changes in the tubal cellular microenvironment (imbalance of NO production) on tubal dysfunction and the potential involvement of NOS isoforms in tubal EP after Chlamydia trachomatis genital infection. The non-equivalent regulation of tubal NOS isoforms during the menstrual cycle suggests that endogenous ovarian steroid hormones regulate NOS in an isoform-specific manner. The current literature suggests that infection with C. trachomatis induces an inflammatory response that eventually leads to tubal epithelial destruction and functional impairment, caused by a high NO output mediated by inducible NOS (iNOS). Therefore, tissue-specific therapeutic approaches to suppress iNOS expression may help to prevent ectopic implantation in patients with prior C. trachomatis infection of the Fallopian tube.

Original languageEnglish (US)
Article numbergaq063
Pages (from-to)907-915
Number of pages9
JournalMolecular Human Reproduction
Issue number12
StatePublished - Dec 2010
Externally publishedYes


  • Chlamydia trachomatis
  • Nitric oxide
  • Nitric oxide synthase isoforms
  • Tubal ectopic pregnancy

ASJC Scopus subject areas

  • Reproductive Medicine
  • Embryology
  • Molecular Biology
  • Genetics
  • Obstetrics and Gynecology
  • Developmental Biology
  • Cell Biology


Dive into the research topics of 'Nitric oxide synthases and tubal ectopic pregnancies induced by Chlamydia infection: Basic and clinical insights'. Together they form a unique fingerprint.

Cite this