Objective To investigate the expressions of hypothalamic arginine vasopressin (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 testify the effects of AM given 0 5?g/kg daily on NS Hypothalamic AVP mRNA expression 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 mRNA of glyceraldehyde 3 phosphate dehydrogenase from the same sample Results All rats receiving adriamycin presented typical nephrosis No obvious difference in plasma osmolality was detected among NS, NS+AM, and normal control (NC) rats Hypothalamic AVP mRNA expression was higher in NS rats than NC (53 59±5 49 vs 25 72±1 96, P <0 01) AM completely reversed this up regulated expression (21 88±1 25) In both cortex and medulla of the kidney, nephrotic rat had increased AVP V 2 expressions by 169% and 55%, respectively, compared with normal control rat The increment of expression 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 induced nephrotic rats AM exerts its therapeutical effects on nephrosis partially through this mechanism Objective To investigate the expressions of hypothalamic arginine vasopressin (AVP) mRNA, and AVP dependent aquaporin 2 (AQP 2) mRNA in rats with adriamycin-induced nephrotic syndrome Effects of Chinese Herb Astragalus membranaceus (AM) 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 testify the effects of AM given 0 5? G / kg daily on NS Hypothalamic AVP mRNA expression 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 mRNA of glyceraldehyde 3 phosphate dehydrogenase from the same sample Results All rats receiving adriamycin presented typical nephrosis No obvious difference in plasma osmolality was detected among NS, NS + AM, and normal control (NC) rats Hypothalamic AVP mRNA expression was higher in NS rats than NC (53 59 ± 5 49 vs 25 72 ± 1 96, P <0.01) kidney, nephrotic rat had increased AVP V 2 expressions by 169% and 55%, respectively, compared with normal control rat The increment of expression of AQP 2? mRNA was consistent with that of V 2 receptor in NS rat AM could partially but 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-induced nephrotic rats AM exerts its therapeutical effects on nephrosis partially through this mechanism