An age- and blood pressure-associated increase in methylglyoxal (MG) and MG-induced advanced glycation endproducts (AGEs), including N(epsilon)-carboxyethyl-lysine (CEL) and N(epsilon)-carboxymethyl-lysine (CML), in the kidney of spontaneously hypertensive rats (SHR) has been shown. In the present study, gender-related changes in AGEs and nitric oxide synthase were investigated in Sprague-Dawley (SD) and stroke-prone SHR (SHRsp) rats. Immunohistochemical analyses were conducted on kidneys from 24-week-old male and female SD rats as well as SHRsp. The systolic blood pressure of SHRsp was significantly higher than that of SD rats. Male SD rats had more intense kidney staining for CEL than female SD rats. Both male and female SHRsp had more marked CEL and CML staining localized to kidney tubules, as opposed to SD rats. Female rats showed more staining in glomerular vessels than male rats in both SD and SHRsp. Nuclei containing nuclear factor-kappaB (NF-kappaB) p65 and activated macrophages were seen in the kidney from SHRsp, not so much in SD rats, localized to renal tubules in male and glomerular vessels in female SHRsp. A higher protein level of NF-kappaB p65 was found in SHRsp than in SD rats. SD rats had more intense kidney neuronal nitric oxide synthase staining than SHRsp. The intensity of inducible nitric oxide synthase staining was significantly higher in SHRsp than in SD rats, with no gender differences in either strain. SHRsp and male rats exhibited higher AGEs and oxidative stress than SD and female rats, respectively. These differences might partly account for the development of hypertension in SHRsp and the higher vulnerability of male animals to renal pathology.

Valproic acid (VPA) has been shown to cause neural tube defects in humans and mice, but its mechanism of action has not been elucidated. We hypothesize that alterations in embryonic antioxidant status and Hoxa2 gene expression play an important role in VPA-induced teratogenesis. A whole embryo culture system was applied to explore the effects of VPA on total glutathione, on glutathione in its oxidized (GSSG) and reduced (GSH) forms [GSSG/GSH ratio] and on Hoxa2 expression in cultured CD-1 mouse embryos during their critical period of organogenesis. Our results show that VPA can (1) induce embryo malformations including neural tube defects, abnormal flexion, yolk sac circulation defects, somite defects, and craniofacial deformities such as fusion of the first and second arches, and (2) alter glutathione homeostasis of embryos through an increase in embryonic GSSG/GSH ratio and a decrease in total GSH content in embryos. Western blot analysis and quantitative real-time RT-PCR show that VPA can inhibit Hoxa2 expression in cultured embryos at both the protein and mRNA level, respectively. The presence of ascorbic acid in the culture media was effective in protecting embryos against oxidative stress induced by VPA and prevented VPA-induced inhibition of Hoxa2 gene expression. Hoxa2 null mutant embryos do not exhibit altered glutathione homeostasis, indicating that inhibition of Hoxa2 is downstream of VPA-induced oxidative stress. These results are first to suggest VPA may, in part, exert its teratogenicity through alteration of the embryonic antioxidant status and inhibition of Hoxa2 gene expression and that ascorbic acid can protect embryos from VPA-induced oxidative stress.

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