Preventive Effects of a Natural Anti-Inflammatory Agent, Astragaloside IV, on Ischemic Acute Kidney Injury in Rats

Abstract

This study investigated the anti-inflammatory effects of astragaloside IV(AS-IV) on ischemia/reperfusion (IR) induced acute kidney injury (AKI) in rats. Experimental model of ischemic AKI was induced in rats by bilateral renal artery clamp for 45 min followed by reperfusion of 12 h and 24 h, respectively. AS-IV was orally administered once a day to rats at 10 and 20 mg·kg(-1)·d(-1) for 7 days prior to ischemia. AS-IV pretreatment significantly decreased serum urea, creatinine, and cystatin C levels at 12 h and 24 h of reperfusion in AKI rats. AS-IV pretreatment also ameliorated tubular damage and suppressed the phosphorylation of p65 subunit of NF- κ B in AKI rats. Moreover, NF- κ B and MPO activity as well as serum and tissue levels of TNF- α , MCP-1, and ICAM-1 were elevated in AKI rats. All of these abnormalities were prevented by AS-IV. Furthermore, AS-IV downregulated the mRNA expression of NF- κ B, TNF- α , MCP-1, and ICAM-1 in AKI rats. These results suggest that AS-IV might be developed as a novel therapeutic approach to prevent ischemic AKI through inhibition of NF- κ B mediated inflammatory genes expression.

Figure 1

Astragaloside IV(AS-IV) improved renal dysfunction in rats with ischemic AKI. Serum creatinine (a), BUN (c), and cystatin C (e) in sham, vehicle-, or AS-IV-pretreated rats at 12 h of reperfusion. Serum creatinine (b), BUN (d), and cystatin C (f) in sham, vehicle-, or AS-IV-pretreated rats at 24 h of reperfusion. Sham, sham-operated rats treated with normal saline; Veh, ischemia-reperfusion (IR) rats pretreated with carboxymethyl cellulose vehicle alone served as control; AL, IR rats pretreated with AS-IV (10 mg·kg⁻¹·d⁻¹); AH, IR rats pretreated with AS-IV (20 mg·kg⁻¹·d⁻¹). Results are expressed as mean ± SD (n = 8). *P < 0.05 versus Sham group; ^# P < 0.05 versus Veh group.

Figure 2

AS-IV significantly ameliorated histological damage in rats with ischemic AKI. Representative hematoxylin and eosin (HE-) stained kidney sections from sham, vehicle-, or AS-IV-pretreated rats at 12 h and 24 h of reperfusion. Histopathologic scoring of tubular injury in kidneys at 12 h and 24 h of reperfusion. Results are expressed as mean ± SD. *P < 0.05 versus Sham group; ^# P < 0.05 versus Veh group.

Figure 3

AS-IV decreased renal MPO activity and inhibited the activity and mRNA expression of NF-κB in rats with ischemic AKI. Renal MPO activity (a), NF-κB activity (b), and mRNA expression (c) in sham, vehicle-, or AS-IV-pretreated rats at 12 h of reperfusion. Renal MPO activity (d), NF-κB activity (e), and mRNA expression (f) in sham, vehicle-, or AS-IV-pretreated rats at 24 h of reperfusion. Results are expressed as mean ± SD. *P < 0.05 versus Sham group; ^# P < 0.05 versus Veh group.

Figure 4

AS-IV suppressed the phosphorylation of p65 subunit of NF-κB in rats with ischemic AKI. Representative Western blot of phosphorylated and total NF-κB in sham, vehicle-, or AS-IV-pretreated rats at 4 h, 12 h, and 24 h of reperfusion. Lamin A was used as a loading control. Results are expressed as mean ± SD. *P < 0.05 versus Sham group; ^# P < 0.05 versus Veh group.

Figure 5

AS-IV decreased the serum levels of TNF-α, MCP-1, and ICAM-1 in rats with ischemic AKI. Serum levels of TNF-α (a), MCP-1 (b), and ICAM-1 (c) in sham, vehicle-, or AS-IV-pretreated rats at 12 h of reperfusion. Serum levels of TNF-α (d), MCP-1 (e), and ICAM-1 (f) in sham, vehicle-, or AS-IV-pretreated rats at 24 h of reperfusion. Results are expressed as mean ± SD (n = 8). *P < 0.05 versus Sham group; ^# P < 0.05 versus Veh group.

Figure 6

AS-IV reduced the protein content of MCP-1, ICAM-1, and TNF-α in rats with ischemic AKI. The protein content of TNF-α (a), MCP-1 (b), and ICAM-1 (c) in renal tissues from sham, vehicle-, or AS-IV-pretreated rats at 12 h of reperfusion. The protein content of TNF-α (d), MCP-1 (e), and ICAM-1 (f) in renal tissues from sham, vehicle-, or AS-IV-pretreated rats at 24 h of reperfusion. Results are expressed as mean ± SD (n = 8). *P < 0.05 versus Sham group; ^# P < 0.05 versus Veh group.

Figure 7

AS-IV downregulated the mRNA expression of TNF-α, MCP-1, and ICAM-1 in rats with ischemic AKI. Representative real-time PCR of TNF-α (a), MCP-1 (b), and ICAM-1 (c) in renal tissues from sham, vehicle-, or AS-IV-pretreated rats at 12 h of reperfusion. Representative real-time PCR of TNF-α (d), MCP-1 (e), and ICAM-1 (f) in renal tissues from sham, vehicle-, or AS-IV-pretreated rats at 24 h of reperfusion. Results are expressed as mean ± SD. *P < 0.05 versus Sham group; ^# P < 0.05 versus Veh group.