Increase in tetrahydrobiopterin concentration with aging in the cerebral cortex of the senescence-accelerated mouse prone 10 strain caused by abnormal regulation of tetrahydrobiopterin biosynthesis.

6R-L-Erythro-5,6,7,8-tetrahydrobiopterin (BH4) is an essential cofactor for tyrosine hydroxylase (TH) activity and is a risk factor for cognitive decline and brain atrophy. Previous studies have shown that the decline in TH activity in the cerebral cortex of senescence-accelerated mouse prone 10 (SAMP10) mice is caused, at least in part, by a decrease in Fe, ferritin, and TH phosphorylation. We determined the concentrations of BH4 and the enzymes GTP cyclohydrolase-1,6-pyruvoyltetrahydropterin synthase and sepiapterin reductase (SPR) in the de novo pathway of BH4 biosynthesis.

Humic acid induces the endothelial nitric oxide synthase phosphorylation at Ser1177 and Thr495 Via Hsp90α and Hsp90β upregulation in human umbilical vein endothelial cells.

Humic acid (HA) has been implicated as a contributory factor for blackfoot disease, which is an endemic peripheral vascular disease. We investigated the effect of HA on the regulation of endothelial nitric oxide (NO) synthase (eNOS) in human umbilical vein endothelial cells (HUVECs) to evaluate the involvement of eNOS and related factors in peripheral vascular impairment with HA exposure. Treatment of HUVECs with HA induced upregulation of eNOS.

Deficiency of catecholamine syntheses caused by downregulation of phosphorylation of tyrosine hydroxylase in the cerebral cortex of the senescence-accelerated mouse prone 10 strain with aging.

The purpose of this study was to elucidate the alteration of catecholamine metabolism and the contribution of catecholamines to the decline of learning and memory in the brain of the senescence-accelerated mouse prone 10 (SAMP10) with aging. Catecholamines and their metabolites in the cerebral cortex were measured by HPLC-ECD. The protein levels of tyrosine hydroxylase (TH) as well as TH phosphorylated at Ser19 or Ser40, dopamine-β-hydroxylase (DβH), and cAMP-dependent protein kinase (PKA) were determined by western blot analysis.