Age-dependent redox status in the brain stem of NO-deficient hypertensive rats

Abstract Background The brain stem contains important nuclei that control cardiovascular function via the sympathetic nervous system (SNS), which is strongly influenced by nitric oxide. Its biological activity is also largely determined by oxygen free radicals. Despite many experimental studies, the role of AT1R-NAD(P)H oxidase-superoxide pathway in NO-deficiency is not yet sufficiently clarified. We determined changes in free radical signaling and antioxidant and detoxification response in the brain stem of young and adult Wistar rats during chronic administration of exogenous NO inhibitors. Methods Young (4 weeks) and adult (10 weeks) Wistar rats were treated with 7-nitroindazole (7-NI group, 10 mg/kg/day), a specific nNOS inhibitor, with NG-nitro-L-arginine-methyl ester (L-NAME group, 50 mg/kg/day), a nonspecific NOS inhibitor, and with drinking water (Control group) during 6 weeks. Systolic blood pressure was measured by non-invasive plethysmography. Expression of genes (AT1R, AT2R, p22phox, SOD and NOS isoforms, HO-1, MDR1a, housekeeper GAPDH) was identified by real-time PCR. NOS activity was detected by conversion of [3H]-L-arginine to [3H]-L-citrulline and SOD activity was measured using UV VIS spectroscopy. Results We observed a blood pressure elevation and decrease in NOS activity only after L-NAME application in both age groups. Gene expression of nNOS (youngs) and eNOS (adults) in the brain stem decreased after both inhibitors. The radical signaling pathway triggered by AT1R and p22phox was elevated in L-NAME adults, but not in young rats. Moreover, L-NAME-induced NOS inhibition increased antioxidant response, as indicated by the observed elevation of mRNA SOD3, HO-1, AT2R and MDR1a in adult rats. 7-NI did not have a significant effect on AT1R-NADPH oxidase-superoxide pathway, yet it affected antioxidant response of mRNA expression of SOD1 and stimulated total activity of SOD in young rats and mRNA expression of AT2R in adult rats. Conclusion Our results show that chronic NOS inhibition by two different NOS inhibitors has age-dependent effect on radical signaling and antioxidant/detoxificant response in Wistar rats. While 7-NI had neuroprotective effect in the brain stem of young Wistar rats, L-NAME- induced NOS inhibition evoked activation of AT1R-NAD(P)H oxidase pathway in adult Wistar rats. Triggering of the radical pathway was followed by activation of protective compensation mechanism at the gene expression level

<i>N</i>-Glycoprofiling of SLC35A2-CDG: Patient with a Novel Hemizygous Variant

Congenital disorders of glycosylation (CDG) are a group of rare inherited metabolic disorders caused by a defect in the process of protein glycosylation. In this work, we present a comprehensive glycoprofile analysis of a male patient with a novel missense variant in the SLC35A2 gene, coding a galactose transporter that translocates UDP-galactose from the cytosol to the lumen of the endoplasmic reticulum and Golgi apparatus. Isoelectric focusing of serum transferrin, which resulted in a CDG type II pattern, was followed by structural analysis of transferrin and serum N-glycans, as well as the analysis of apolipoprotein CIII O-glycans by mass spectrometry. An abnormal serum N-glycoprofile with significantly increased levels of agalactosylated (Hex3HexNAc4-5 and Hex3HexNAc5Fuc1) and monogalactosylated (Hex4HexNAc4 ± NeuAc1) N-glycans was observed. Additionally, whole exome sequencing and Sanger sequencing revealed de novo hemizygous c.461T > C (p.Leu154Pro) mutation in the SLC35A2 gene. Based on the combination of biochemical, analytical, and genomic approaches, the set of distinctive N-glycan biomarkers was characterized. Potentially, the set of identified aberrant N-glycans can be specific for other variants causing SLC35A2-CDG and can distinguish this disorder from the other CDGs or other defects in the galactose metabolism