Angiotensins II and IV stimulate the rat adrenocortical cell proliferation acting via different receptors

Abstract

Objective: The effects of angiotensins II (Ang II) and IV (Ang IV,3-8 fragment of angiotensin II) on the adrenocortical cell proliferation have been investigated in the rat.

Methods: The male adult Wistar rats were injected subcutaneously with saline, captopril or captopril together with either Ang II or Ang IV. A part of animals received additionally losartan - an antagonist of AT1 subtype of angiotensin receptors. Bromodeoxyuridine (BrDU) incorporation into cell nuclei was used as the index of cell proliferation.

Results: It was found that both Ang II and Ang IV increased the BrDU labeling in the adrenal cortex of captopril-pretreated rats. This effect involved mainly the zona glomerulosa cells. The proliferogenic effect of Ang II was blocked by AT1 receptor antagonist losartan. In contrast, losartan did not block the effect of Ang IV.

Conclusion: Both Ang II and Ang IV stimulate the adrenocortical cell proliferation in the rat, but they act via different receptors - AT1 in the case of Ang II and non-AT1 (probably AT4) in the case of Ang IV.