Aim: 

Angiotensin II (Ang II), an effector of renin-angiotensin system (RAS), is effective as a vasoconstrictor and also as a proliferative and hypertrophic agent. Others and we have shown that adipose tissue possesses a biologically active local RAS. The locally produced Ang II may be implicated in the regulation of adipocyte growth and differentiation. This study was aimed to assess the components of local RAS and some markers of insulin sensitivity in adipose tissue in rats at different age (9-, 12-, 20- and 26-weeks).

Methods: 

Circulated levels of hormones in serum were determined by radioimmunoassay. Gene expression of adipokines and RAS components in adipose tissue were evaluated by RT-PCR. AT1 receptor protein was determined by immunoblot.

Results: 

Hypertrophic adipose tissue contains large insulin resistant adipocytes. Our results show that fat tissue enlargement due to maturation of the rats is associated with an increase in AT1 receptor gene expression and protein, and with a decrease of angiotensin-converting enzyme and angiotensinogen gene expression. At the same time, leptin expression increased significantly in adult rats. On the contrary, PPARg and GLUT4 were significantly reduced whilst adiponectin was not changed in the studied age intervals.

Conclusion: 

Our results suggest a complex pattern of RAS involvement in adipose tissue enlargement with probably an inhibitory role of AT1 receptors on adipocyte differentiation leading to tissue hypertrophy and insulin resistance.

Supported by grant VEGA 2/ 5090/ 25.