Maternal protein restriction that does not have an influence on the birthweight of the offspring induces morphological changes in kidneys reminiscent of phenotypes exhibited by intrauterine growth retardation rats.

Severe restriction of maternal protein intake to 6-8% protein diet results in intrauterine growth retardation (IUGR), low birthweight and high risk of metabolic syndrome in the adult life of the offspring. However, little information is available on the effects of maternal protein restriction on offspring under the conditions that does not have an influence on their birthweight of the offspring,. In the present study, pregnant rats were kept on a diet consisting of either 9% (low-protein, Lp rats) or 18% (normal-protein, Np rats) protein by weight/volume/etc. After birth, both Lp and Np rats were kept on a diet containing 18% protein. Neonatal body weight was significantly lower in Lp rats compared to Np rats from 4 days to 5 weeks after birth. While glomerular number per unit volume (1 mm(3) ) of the kidney (Nv) was comparable between Lp and Np rats 4 weeks after birth, the Nv was significantly decreased in Lp rats at 20 weeks after birth. Four and 20 weeks after birth, glomerular sclerosis index, interstitial fibrosis score, and ratio of ED1-positive cell ratio were all significantly higher in Lp compared to Np rats. Transforming growth factor-β1-positive cells were observed in the distal tubules in the kidney of 4- and 20-week-old Lp rats kidneys, but not in those of age-matched Np rats. Altogether, these findings revealed that maternal protein restriction that does not have an influence on the birthweight of the offspring, induces similar changes as those seen in the kidneys of IUGR neonates.