Protective effect of moxonidine on ischemiaireperfusion-induced acute kidney injury through α2/imidazoline I1 receptor

Enhancement of renal sympathetic nerve activity during renal ischemia and norepinephrine overflow from the kidney after reperfusion play important roles in the development of ischemic acute kidney injury. Recently, we have found that moxonidine, an alpha 2/imidazoline I-1-receptor agonist, has preventive effects on ischemic acute kidney injury by suppressing the excitation of renal sympathetic nervous system after reperfusion. In the present study, to clarify the renoprotective mechanisms of moxonidine (360 nmol/kg, iv,) against ischemic acute kidney injury, we investigated the effect of intravenous (ix.) and intracerebroventricular (i.c.v) injection of efaroxan, an alpha 2/I-1 receptor antagonist, on the moxonidine-exhibited actions. Ischemic acute kidney injury was induced by clamping the left renal artery and vein for 45 min followed by reperfusion, 2 weeks after contralateral nephrectomy. The suppressive effect of moxonidine on enhanced renal sympathetic nerve activity during renal ischemia was not observed in the rat treated with either iv. (360 nmol/kg) or i.c.v. (36 nmol/kg) of efaroxan. Furthermore, iv. injection of efaroxan eliminated the preventive effect of moxonidine on ischemiaffeperfusion-induced kidney injury and norepinephrine overflow, and i.c.v. injection of efaroxan did not completely inhibit the moxonidine's effects. These results indicate that moxonidine prevents the ischemic kidney injury by sympathoinhibitory effect probably via alpha 2/I-1 receptors in central nervous system and by suppressing the norepinephrine overflow through alpha 2/I-1 receptors on sympathetic nerve endings. 2013 Elsevier B.V. All rights reserved.