OBJECTIVETo study the effect of L-arginine (L-Arg) on Pax2 expression in the kidneys of pup rats with intrauterine growth retardation (IUGR).

METHODSPregnant rats were randomly assigned into three groups：normal, IUGR and L-Arg treated IUGR. The rats in the normal group were fed with ordinary forage (21% protein) during pregnancy. Those in the other two groups were fed with low diet forage (10% protein) during pregnancy. The L-Arg treated group was given drinking water containing L-Arg (200 mg/kg) daily during 21 days of lactation. Pax2 expression in renal tissues was measured with immunohistochemical staining and Western blot in pup rats of 7 days, 21 days, 2 months and 3 months old.

RESULTSThe immunohistochemical staining showed that Pax2 was not expressed in the pup rats from the normal group at any time point. Pax2 positive cells were found in renal glomerulus and kidney tubules of 2-months- and 3-months-old rats from the IUGR and L-Arg treated groups. And Pax2 expression in 3-months-old rats was significantly higher than that in 2-months-old rats (P<0.05). L-Arg treatment decreased significantly the Pax2 expression in 2-months- and 3-months-old rats when compared with the untreated IUGR group (P<0.05). Western blot showed that Pax2 protein was not expressed in 7-days- and 21-days-old pup rats from three groups. Pax2 protein expression in 2-months- and 3-months-old pup rats from the IUGR and L-Arg treated groups increased significantly compared with normal controls. Pax2 protein expression in the pup rats from the L-Arg treated group was significantly lower than that in the untreated IUGR pup rats (P<0.01).

CONCLUSIONSPax2 is expressed in the kidneys of IUGR rats during adulthood. L-Arg treatment can decrease the expression of Pax2.