Chronic oestrogen deficiency induced by ovariectomy may cause lung fibrosis through activation of the renin-angiotensin system in rats

Abstract

Context

Oestrogen deficiency is linked with pulmonary fibrosis. Additionally, it may lead to over-activation of the renin-angiotensin system (RAS), which worsens lung fibrosis.

Objective

The present study aims to investigate the role of RAS on lung fibrosis associated with oestrogen deficiency in ovariectomised rats.

Materials and methods

Serum 17_β-oestradiol (E2), arterial blood gases, plasma angiotensin II levels, lung tissue hydroxyproline content, and transforming growth factor beta 1 (TGF-β1) concentration, the mRNA expression of angiotensin type 1 receptor (AT1R), and angiotensin-converting enzyme (ACE1) were evaluated. Moreover, lung tissues were examined by histopathology and immunohistochemistry.

Results

Hydroxyproline content, TGF-β1 concentration, plasma angiotensin II, the relative mRNA expression of ACE1, and AT1R is found to increase in ovariectomised rats. The mentioned changes can be largely rescued by administration of RAS blockers.

Conclusion

Oestrogen deficiency activates RAS, which consequently increases the expression of pro-fibrotic factors and stimulates the fibrotic cascade causing lung fibrosis.

Keywords:

• Oestrogen deficiency
• lung fibrosis
• renin-angiotensin system
• TGF-β1
• losartan
• aliskiren

Acknowledgments

We gratefully thank the technical and administrative staff at the Physiology, Anatomy, and Pharmacology Departments, Faculty of Medicine, Benha University, for their assistance and support.

Disclosure statement

No potential conflict of interest was reported by the authors.