Description:
<jats:p> We studied regulation of the AT<jats:sub>2</jats:sub> receptor by investigating the effect of bilateral nephrectomy (bNX) in Sprague–Dawley rats. The expression of aldosterone synthase (CYP11B2) and AT<jats:sub>2</jats:sub> receptor mRNA was detected by nonradioactive in situ hybridization. AT<jats:sub>2</jats:sub> receptor mRNA was detected in cells of the first two or three subcapsular cell layers of the zona glomerulosa (ZG) and in the medulla of sham-operated animals. After bNX, the number and area of distribution of AT<jats:sub>2</jats:sub> receptor-positive cells increased in the ZG. This was associated with an enlargement of the steroidogenic active ZG and with reduced proliferation rate (sham 5.9 ± 0.9%; bNX 2.4 ± 0.2%; p > 0.02). Infusion of angiotensin II (ANG II; 200 ng/kg/min SC for 56 hr) to bNX rats did not reverse the effect of nephrectomy on the distribution of AT<jats:sub>2</jats:sub> receptor expression, although mRNA levels per cell were reduced compared to NX alone. ANG II infusion decreased proliferation rate further (0.4 ± 0.07%; p > 0.001). In the adrenal medulla after bNX, decreased expression of the AT<jats:sub>2</jats:sub> receptor was associated with increased proliferation (2.6 ± 0.2% vs 6.6 ± 0.5%). These results demonstrate differential regulation of the AT<jats:sub>2</jats:sub> receptor in the adrenal gland and suggest that expression of the AT<jats:sub>2</jats:sub> receptor is involved in regulating proliferation and differentiation in the ZG and medulla. </jats:p><jats:p> (J Histochem Cytochem 49:649–656, 2001) </jats:p>