Messenger RNA expressions of vasopressin system and aquaporin-2 in adriamycin-induced nephrotic rats and effects of astragalus membranaceus

Objective To investigate the expressions of hypothalamic arginine vasopress in (AVP) mRNA, renal AVP V-2 receptor mRNA, and AVP-dependent aquaporin-2 ( AQP(2)) mRNA in rats with adriamycin-induced nephrotic syndrome. Effects of Chinese herb Astragalus membranaceus (AM) were also tested. Methods Sprague-Dawley rats with four weeks of adriamycin-induced nephrotic syndrome (NS) were used in this study. Another group NS + AM was set to te stify the effects of AM given 0.5 g/kg daily on NS. Hypothalamic AVP mRNA e xpression was examined by dot blot method. Reverse transcription polymerase chain reaction was applied for detection of renal cortical and medullary V -2 receptor and AQP(2) mRNA. The results were normalized by of glyceraldehy de-3-phosphate dehydrogenase the same sample. AQP(2) by mRNA. mRNA. Results All rats receiving adriamycin presented typical nephrosis. No obvio us difference in plasma osmolality was detected among NS, NS + AM, and norm al control (NC) rats. Hypothalamic AVP mRNA expression was higher in NS rat s than NC (53.59 +/- 5.49 vs 25.72 +/- 1.96, P < 0.01). AM completely rever sed this up-regulated expression (21.88 +/- 1.25). In both cortex and medul la of the kidney, nephrotic rat had increased AVP V-2 expressions by 169% a nd 55%, respectively, compared with normal control rat. The increment of ex pression of AQP(2) mRNA was consistent with that of V-2 receptor in NS rat, AM could partially however significantly correct these up-regulations of V -2 and AQP(2) mRNA expressions (P < 0.01). Conclusion The up-regulated mRNA expressions of hypothalamic AVP, renal V-2 receptor and AQP(2) might play a role in edema formation in adriamycin-ind uced nephrotic rats. AM exerts its therapeutical effects on nephrosis parti ally through this mechanism.