Developmental changes in AT1 and AT2 receptor-protein expression in rats

Area of Science:

• Physiology
• Endocrinology
• Developmental Biology

Background:

• Angiotensin type-1 receptors (AT1R) are crucial for sympathetic regulation and cardiovascular activity.
• The functional role of angiotensin type-2 receptors (AT2R) remains poorly understood.
• Previous research indicated an imbalance of AT1R and AT2R in chronic heart failure, contributing to sympatho-excitation.

Purpose of the Study:

• To investigate the developmental expression patterns of AT1R and AT2R in rat brainstem, kidney, and liver.
• To challenge the prevailing dogma regarding AT2R expression during fetal and adult life.

Main Methods:

• Western blot analysis was used to quantify AT1R and AT2R protein levels.
• Expression was measured in male and female rats at different life stages: fetal, neonatal, adult, and aged.

Main Results:

• Contrary to existing dogma, AT2R protein expression was significantly lower in fetal and neonatal rats compared to adults in the brainstem.
• AT1R protein expression was significantly higher in fetal and neonatal rats than in adults in the brainstem.
• Kidney AT2R expression increased with age, while AT1R expression was highest in fetuses.
• Liver AT2R was higher in fetuses and neonates than adults, with AT1R higher in fetuses than neonates.

Conclusions:

• The study findings contradict the established view of higher fetal AT2R expression.
• These results suggest a potentially significant functional role for AT2R in adult animals.
• The findings also imply an important role for AT1R in fetal development and physiology.