Location and regulation of rat angiotensinogen messenger RNA

The presence of angiotensinogen messenger RNA (mRNA) was detected in rat vascular and adipose tissue. Angiotensinogen mRNA in rat aorta was localized in the adventitia and surrounding adipose tissue, and not in the vascular smooth muscle. Freshly dispersed and cultured endothelial and aortic smooth muscle cells did not contain detectable amounts of angiotensinogen mRNA. In addition to periaortic adipose tissue, angiotensinogen mRNA was present in other fat depots of both brown and white types. To examine regulation of angiotensinogen gene expression, Sprague-Dawley rats were treated with angiotensin converting enzyme inhibitor or underwent bilateral nephrectomy. Relative levels of angiotensinogen mRNA in brown adipose tissues increased dramatically by 48 hours after bilateral nephrectomy. However, only one source of brown adipose tissue showed increased angiotensinogen mRNA levels after animals were treated for 5 days with converting enzyme inhibitor. In addition, angiotensinogen was released into the medium from incubated adipose tissues with levels increasing over a 2-hour period. These results demonstrate that angiotensinogen is synthesized by adipose tissue in the rat and may play a role in the function of this tissue.