α-MSH prevents impairment in renal function and dysregulation of AQPs and Na-K-ATPase in rats with bilateral ureteral obstruction

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Abstract
The purpose of this study was to evaluate the effects of the anti-inflammatory hormone α-melanocyte-stimulating hormone (α-MSH) treatment on renal function and expression of aquaporins (AQPs) and Na-K-ATPase in the kidney in response to 24 h of bilateral ureteral obstruction (BUO) or release of BUO (BUO-R). In rats with 24-h BUO, immunoblotting revealed that downregulation of AQP2 and AQP3 was attenuated (AQP2: 38 ± 5 vs. 13 ± 4%; AQP3: 44 ± 3 vs. 19 ± 4% of sham levels; P < 0.05 ), whereas downregulation of Na-K-ATPase was prevented by α-MSH treatment (Na-K-ATPase: 94 ± 7 vs. 35 ± 5% of sham levels; P < 0.05). Immunocytochemistry confirmed the changes in AQP1 and Na-K-ATPase expression. Renal tubular cell apoptosis was confirmed in BUO kidneys, and α-MSH treatment virtually completely abolished apoptosis. Furthermore, we measured glomerular filtration rate (GFR) and effective renal plasma flow (ERPF), respectively. Forty-eight hours after BUO-R demonstrated that α-MSH treatment almost completely prevented the decrease in GFR (nontreated: 271 ± 50; α-MSH: 706 ± 85; sham: 841 ± 105 μl·min−1·100 g body wt−1, P < 0.05) and ERPF (nontreated: 1,139 ± 217; α-MSH: 2,598 ± 129; sham: 2,633 ± 457 μl·min−1·100 g body wt−1, P < 0.05). α-MSH treatment also partly prevented the downregulation of AQP1 and Na-K-ATPase expression in rats after BUO-R for 48 h. In conclusion, α-MSH treatment significantly prevents impairment in renal function and also prevents downregulation of AQP2, AQP3, and Na-K-ATPase during BUO or AQP1 and Na-K-ATPase after BUO-R, demonstrating a marked renoprotective effect of α-MSH treatment in conditions with urinary tract obstruction.