Abstract-This paper describes the distribution of aromatic L-amino acid decarboxylase (AADC) activities in fourteen tissues (eight peripheral tissues and six brain regions) of semicarbazide (SC)-treated rats, using both L DOPA and L-5-hydroxytryptophan (L-5-HTP) as substrates. The distri bution of pyridoxal phosphate (PLP) was also measured in control and SC-treated rats. SC-treatment decreased the PLP concentration in all tissues (about 50-60% of control). AADC activities towards L-DOPA and L-5-HTP as substrates were also decreased significantly in almost all tissues of SC-treated rats. After the addition of exogenous PLP in vitro, AADC activities were recovered only partially in most tissues, but the recovery patterns were not parallel between L-DOPA and L-5-HTP as substrates. L-DOPA decarboxylase activity was more sensitive to PLP-deficiency than L-5-HTP decarboxylase activity in the same tissues. Serum AADC activities were decreased drastically using both L-DOPA and L-5-HTP as substrates . No serum AADC activity was detected in SC-treated rats using L-DOPA as substrate, but low activity was detected in the same sample using L-5-HTP as the substrate; both activities recovered completely after in vitro addition of 10 W PLP in the incubation mixtures.
Ubiquitin and ubiquitin-protein conjugates in PC12h cells were detected with in vitro [125I]ubiquitination, and quantified by immunoblotting. These levels were altered by nerve growth factor (NGF), which promotes neuronal differentiation. (i) Levels of high molecular weight (HMW) ubiquitin-protein conjugates ranging from 40 to 1,000 kDa were increased by 2 days of NGF treatment, and remained high up to 10 days of NGF treatment. (ii) Ubiquitin and a 23-kDa conjugate tended to be decreased from days 2 to 10 of NGF treatment. 10-Day culture with 10 nM staurosporine, n protein kinase inhibitor, that blocks NGF-induced neurite outgrowth suppressed the NGF-induced increases in levels of HMW conjugates. Cyclic AMP and forskolin, both of which promote neurite outgrowth, mimicked the NGF-induced changes in ubiquitin and HMW conjugates, but phorbol ester and epidermal growth factor had little effect. These findings suggest that changes in ubiquitin-protein conjugates are closely coupled with neuronal differentiation.
Summary[3H] Pyridoxamine was orally administered to mice in physiological amounts, and the distribution of isotope between the six recognized forms of vitamin B6 and pyridoxac acid was determined at different times in the intestine, liver, blood, and brain. After 7min about 50% of the radioactivity in pyridoxamine had been absorbed by the intestine and transported to the blood and other organs. Labeled pyridox al phosphate was found in the intestine and liver. Labeled pyridoxamine could not be detected in the peripheral blood, but substantial amounts of labeled pyridoxal and pyridoxal phosphate were found in the blood. However, when a large amount (40-140nmol) was given, a significant amount of labeled pyridoxamine was found in the blood, together with labeled pyridoxal and pyridoxal phosphate. These results suggest that the intestine and/or liver play a major role in completely converting physio logical amounts of pyridoxamine to circulating pyridoxal, which is then taken up and phosphorylated by other organs.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.