The present study investigated whether lowering plasma
homocysteine (Hcy) with
folic acid (FA) could attenuate
hyperhomocysteinemia (HHcy)-associated glomerular damage and possible mechanisms. The HHcy animal model was established by intragastric administration with
l-methionine in rats. FA was also given intragastrically. Plasma Hcy and
creatinine and urinary
albumin were measured. Histological and ultrastructural changes were observed by light and electron microscopes. The expression of alpha-smooth muscle actin (α-SMA),
proliferating cell nuclear antigen (
PCNA) and
transforming growth factor-beta1 (TGF-β1) in the kidney was examined by immunohistochemical staining and western blot analysis. The administration of
l-methionine induced HHcy in rats. The HHcy rats developed glomerulosclerosis and
fibrosis. Plasma
creatinine concentration and urinary
albumin excretion were also significantly increased in HHcy rats. Effacement and extensively fusion of podocyte foot process was observed in HHcy rats, which was associated with decreased expression of
nephrin protein in renal cortex of HHcy rats. Supplementation with FA lowered plasma Hcy significantly. Plasma
creatinine concentration and urinary
albumin excretion were also significantly attenuated by FA. Morphologically, HHcy-associated glomerulosclerosis,
fibrosis, podocyte foot process effacement and loss of podocyte
nephrin, were significantly improved by FA. The expressions of α-SMA,
PCNA and TGF-β1 were increased in renal cortex of HHcy rats, and which were also partially reversed by FA. These data suggest that elevated plasma Hcy is an important pathogenic factor for glomerular damage. Lowering plasma Hcy by FA can inhibit TGF-β1 expression and attenuate HHcy-induced glomerular damage.