Abstract
Purpose: :
The systemic renin-angiotensin system (RAS) plays an important role in the endocrine regulation of blood pressure and of salt and water balance. Besides the systemic RAS, there are reports that many peripheral tissues are capable of generating RAS components. This so called tissue RAS is regulated by physiological and pathological conditions. For example, the local pancreatic RAS is involved in physiological regulation of pancreatic function, as well as being implicated in the pathogenesis of pancreatic disease including diabetes, pancreatitis and pancreatic cancer. The lacrimal gland is an exocrine organ and the pathogenesis of fibrosis and inflammation leads to the dry eye syndrome.We hypothesized that local RAS is present in the lacrimal gland, which may play roles in the physiological function and pathogenesis of lacrimal gland disease.We investigated the expression and localization of RAS components including renin, angiotensin converting enzyme (ACE), angiotensin II, angiotensin II type 1 receptor ( AT1R) and angiotensin II type 2 receptor (AT2R) in mouse lacrimal gland tissue.
Methods: :
Lacrimal gland and cultured lacrimal gland fibroblasts from 8 week-old BALB/c (H-2d) mice were used. Reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry was used to establish the presence and localization of RAS components in normal mouse lacrimal gland.
Results: :
mRNA coding for angiotensinogen, renin, ACE, and both AT1R and AT2R was demonstrated in normal lacrimal gland tissue and cultured lacrimal gland fibroblast. Renin and ACE were identified in blood vessels and myoepithelial cells around the duct and acini. Angiotensin II, AT1R and AT2R were shown in duct and interstitial fibroblast. AT1R and AT2R were also localized in blood vessels. All the cultured lacrimal gland fibroblasts expressed angiotensin II, AT1R and AT2R.
Conclusions: :
The results suggest that a tissue specific RAS is present in lacrimal gland and resident fibroblasts. A local RAS in lacrimal gland may link to tissue function of lacrimal gland; tear secretion and local blood flow. In addition, the activated RAS in fibroblasts may be involved in pathogenic process of fibrosis in lacrimal gland.
Keywords: lacrimal gland • pathology: experimental • gene/expression