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Renin mRNA is synthesized locally in rat ocular tissues
C R Brandt1, A M Pumfery, B Micales
1Department of Ophthalmology and Visual Sciences, University of Wisconsin Medical School, Madison 53706-1532.
Abstract:
Components of the Renin Angiotensin System (RAS) have been detected in ocular tissues and fluids. The source of the ocular RAS proteins is unknown but possibilities include diffusion or leakage from the systemic circulation, specific uptake from the blood, or local synthesis. We have used RT-PCR and in situ hybridization (ISH) to show that renin mRNA is present in ocular tissues from 3 strains of rats. By RT-PCR, we found 10 of 15 ciliary body samples, 13 of 16 iris samples, and 1 of 3 retina samples were positive for renin mRNA. Also, 6 of 6 brain and 7 of 8 kidney samples were positive. Using ISH, we found renin mRNA in the ciliary muscle adjacent to the sclera extending into the choroid. Tissue near the outflow channels of the anterior chamber angle also labeled. Retinal labeling was weak but present in the nerve fiber layer. Clusters of grains, possibly representing blood vessels, were also seen in the ciliary body, iris, and retina using ISH. These results suggest the presence of a local ocular RAS.
Insights
Researchers found renin messenger RNA (mRNA) in rat ocular tissues, suggesting the eye has its own local Renin Angiotensin System (RAS). This indicates potential local synthesis of RAS components within the eye.
Area of Science:
- Ocular physiology
- Molecular biology
- Endocrinology
Background:
- Components of the Renin Angiotensin System (RAS) are found in ocular tissues and fluids.
- The origin of these ocular RAS proteins remains unclear, with possibilities including systemic circulation or local synthesis.
Purpose of the Study:
- To investigate the presence and localization of renin mRNA in ocular tissues.
- To determine if the eye possesses the capacity for local Renin Angiotensin System (RAS) synthesis.
Main Methods:
- Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect renin mRNA.
- In situ hybridization (ISH) was employed to visualize the location of renin mRNA within ocular tissues.
Main Results:
- Renin mRNA was detected in ciliary body, iris, and retina samples from rats.
- ISH confirmed renin mRNA presence in the ciliary muscle, choroid, and anterior chamber angle.
- Weak retinal labeling and potential blood vessel signals were observed.
Conclusions:
- The findings strongly suggest the presence of a local Renin Angiotensin System (RAS) within the eye.
- Local synthesis of renin may contribute to ocular physiology and function.