Prenatal nicotine exposure induced GDNF/c-Ret pathway repression-related fetal renal dysplasia and adult glomerulosclerosis in male offspring

Abstract

This study aimed at investigating whether prenatal nicotine exposure (PNE) could disrupt fetal kidney development and then induce glomerulosclerosis in adult offspring, and to explore its underlying mechanisms. A rat model of intrauterine growth retardation (IUGR) was established by subcutaneous injection with nicotine (1 mg kg⁻¹) to pregnant rats twice a day from gestational day (GD) 9 to GD20. Male fetuses and adult offspring were sacrificed at GD20 and postnatal week 24 (PW24) respectively, and blood and kidneys were collected for analysis. The results indicated that, in the PNE fetuses, the widths of the renal cortical zone and the nephrogenic zone were both significantly reduced. Meanwhile, some glomeruli presented a dilated Bowman's space and a shrunken glomerular tuft, accompanied by the ultrastructural changes, such as extensive fusion and effacement of podocyte foot processes as well as swollen and vacuolar degeneration of the mitochondria. Moreover, in fetal kidneys, the mRNA and protein expression of AT₁R and AT₂R were both inhibited by PNE, associated with the repression of glial cell line derived neurotrophic factor/c-Ret tyrosine kinase receptor (GDNF/c-Ret) signaling pathway-related genes and GDNF protein. In adult offspring of the PNE group, the body weight and kidney weight were decreased, whereas the levels of serum creatinine and urea nitrogen were increased or exhibited an increasing trend. The histological examinations revealed glomerular sclerosis, and q-PCR analysis indicated a marked alternation of renal AT_1aR mRNA abundance as well as the AT_1aR/AT₂R ratio. These results suggested that PNE could induce fetal renal dysplasia associated with the suppression of the GDNF/c-Ret pathway and adult glomerulosclerosis in male offspring, and the dysregulation of renal ATR might be involved in the underlying mechanisms.