Pseudomonas species ATCC 11299a synthesizes tyrosine via an inducible phenylalanine hydroxylase when grown on phenylalanine or tyrosine as a carbon source (G. Guroff and T. Ito, Biochim. Biophys. Acta 77:159, 1963; J. Biol. Chem. 240:1175, 1965). A second pathway to tyrosine synthesis involving transamination between glutamic acid or phenylalanine and p-hydroxyphenylpyruvic acid has been detect...

Objective(s): The effects of low dose amphetamine on oxidative stress and rotenone-induced neurotoxicity and liver injury were examined in vivo in a mice model of Parkinson’s disease. Materials and Methods: Male mice were treated with rotenone (1.5 mg/kg, every other day for two weeks, subcutaneously). Mice received either the vehicle or...

The phosphorylation and activation of tyrosine hydroxylase was examined in PC12 cells following depolarization with KCl or treatment with nerve growth factor. Both treatments activate tyrosine hydroxylase (TH) and increase enzyme phosphorylation. Site-specific analysis of the tryptic phosphopeptides of TH isolated from [32P]phosphate-labeled PC12 cells demonstrated that the major phosphorylated...

The administration of 6-hydroxydopamine into the cerebroventricles of the rat produced a rapid and permanent decrease of norepinephrine in hippocampus due to an apparent degeneration of central catecholaminergic nerve terminals. The decrease in norepinephrine levels was accompanied by a decrease in the activity of the rate-limiting biosynthetic enzyme, tyrosine hydroxylase. However, the decreas...

This chapter describes the aromatic L‐amino acids tryptophan and tyrosine and the effects on tyrosine metabolism of phenylalanine. Tryptophan and phenylalanine are essential amino acids and must ultimately be derived from dietary proteins; tyrosine is obtained both from dietary proteins and from the hydroxylation of phenylalanine by phenylalanine hydroxylase (PAH). The proportions of dietary tr...

Objective(s): Widely used Titanium dioxide nanoparticles (TiO2) enter into the body and cause various organ damages. Therefore, we aimed to study the effect of TiO2 on the substantia nigra of midbrain. Materials and Methods: 40 male BALB/c mice were randomly divided into five groups: three groups received TiO2 at doses of 10, 25, and 50 ...

A recently described new form of hyperphenylalaninemia is characterized by the excretion of 7-substituted isomers of biopterin and neopterin and 7-oxo-biopterin in the urine of patients. It has been shown that the 7-substituted isomers of biopterin and neopterin derive from L-tetrahydrobiopterin and D-tetrahydroneopterin and are formed during hydroxylation of phenylalanine to tyrosine with rat ...

Alterations of tyrosine hydroxylase activity in various regions of brain from rats postnatally exposed to lead were tested. Three groups of animals were prepared; (1) Rats exposed to lead at a low dose (0.05% lead acetate, PbAc); (2) Rats exposed to lead at a high dose (0.2% PbAc); (3) Age-matched normal control rats. At 2, 4, 6, and 8 weeks of age, weight of brain and body, and concentrations ...

We sought to determine the long-term changes produced by neonatal sex hormone administration on the functioning of midbrain dopaminergic neurons in adult male rats. Sprague-Dawley rats were injected subcutaneously at postnatal day 1 and were assigned to the following experimental groups: TP (testosterone propionate of 1.0 mg/50 μL); DHT (dihydrotestosterone of 1.0 mg/50 μL); EV (estradiol valer...