Cereal ingestion and catecholamine excretion

doi:10.1016/0026-0495(74)90101-2

Metabolism

Volume 23, Issue 1, January 1974, Pages 33-41

https://doi.org/10.1016/0026-0495(74)90101-2 Get rights and content

Abstract

We have identified a group of cereal foodstuffs that contain an enzyme, presumably a tyrosinase, which converts dietary tyrosine to dihydroxyphenylalanine (DOPA). Nabisco Wheat Thins and Kretchmer's Wheat Germ are good sources of this enzyme. Urinary catecholamines and their metabolites were measured in subjects ingesting either a cereal-rich diet or a control diet containing milk or eggs as their only protein source. Consumption of the cereal diet was associated with a fourfold increase in the excretion of conjugated dopamine (DA), and a two-fold increase in conjugated dihydroxyphenylacetic acid (DOPAC). Homovanillic acid (HVA) excretion was not significantly influenced by diet. These findings suggest that DOPA is synthesized in the human gastrointestinal tract following the consumption of a cereal-containing diet. Cereal ingestion is thus a potential source of error in clinical studies of catecholamine metabolism.

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The effect of dietary precursors on the excretion of amines and their metabolites in the rat
1985, Biochemical medicine
The influence of diet on the excretion of catecholamines, some of their metabolites, and pHPG, an octopamine metabolite, was examined. Two groups of rats were fed either a cereal-containing standard laboratory Purina rat chow or a cereal-free casein diet. Use of the standard chow resulted in significant increases in the urinary values for total MHPG, pHPG, DHPE, MHPE, and free and total DOPAC by the seventh day in comparison to the casein diet. No changes were noted in the excretion of free and total NE, DA, and HVA. The data indicate that it is necessary to place the animals on the casein diet several days before determining the excretion of the aforementioned metabolites.
Free and conjugated catecholamines in digestive tissues of rats
1985, Life Sciences
Using a radioenzymatic technique, the highest concentrations of free catecholamines were found in the duodenum, and the lowest in the liver of untreated rats. When compared to the antrum, the concentration of free dopamine was higher, and that of norepinephrine lower in the fundus. As far as conjugated catecholamines are concerned, the tissue concentrations of both sulfo- and glucurono-conjugates were usually low, and often non detectable, with an exception: the concentration of glucurono-conjugated dopamine was very high in the duodenum, ileum, and liver of untreated rats.
Effects of intraventricular injections of 6-hydroxydopamine on amine metabolites in rat brain and urine
1985, Biochemical Pharmacology
The effects in rats of intraventricular injections of 6-hydroxydopamine (6-OHDA) on the urinary excretion 1–3 weeks later of 3-methoxy-4-hydroxyphenethylene glycol (MHPG), 3,4-dihydroxyphenethanol (DHPE), 3-methoxy-4-hydroxyphenethanol (MHPE), p-hydroxyphenylglycol (pHPG), homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid (DOPAC) were examined. The excretion of MHPG was decreased to 63 and 71% of control on days 7 and 14, respectively, but had returned to control levels by day 23, even though the brain levels were decreased by 87%. Free and total HVA excretion was reduced on both days 7 and 23, but free and total DOPAC was reduced only on day 7. Based on these data, it can be estimated that about 39% of the free and 46% of the total HVA in urine originates in the CNS. The excretion of conjugated HVA was decreased by 70–80%, but this decrease does not support the notion that the conjugated form of HVA is derived principally from the brain and thus serves as a better marker of brain dopamine metabolism, since the level of this metabolite in the brain was not correspondingly decreased but was instead increased. Urinary DOPAC levels were generally more variable and derived to a greater extent from the periphery; therefore, DOPAC appears to be less suitable than HVA as a marker of brain dopamine. The results also indicate that as much as 35% of the urinary MHPG may originate in the CNS, although compensatory changes in catecholamine metabolism in either the brain or in the periphery may have somewhat influenced this estimate. The results also suggest that at least as much pHPG as MHPG in urine derives from the CNS. The data are consistent with the idea that the neutral dopamine metabolites largely derive from the brain, but the relatively small depletion in their brain levels produced by 6-OHDA prevented the exact proportion being determined accurately.
Effect of dietary proteins and carbohydrates on urinary and sympathoadrenal catecholamines
1985, Neurochemistry International
We previously observed that administration of tyrosine to rats or humans elevated urinary dopamine, norepinephrine and epinephrine levels. The present studies examine the effects on these urinary catecholamines of varying the ratio of protein to carbohydrate in the diets.
Rats consumed diets containing 0, 18 or 40% protein (76, 58 and 36% carbohydrate respectively) for 8 days. The stress of consuming the protein-free food was associated with a 16% weight reduction, and with significantly lower serum, heart and brain tyrosine levels than those noted in rats eating the 18 or 40% protein diets. Absence of protein from the diet also decreased urinary levels of dopamine and DOPA but increased urinary norepinephrine and epinephrine, probably by increasing sympathoadrenal discharge; it also increased the excretion of DOPA in animals pretreated with carbidopa, a DOPA decarboxylase inhibitor. Carbidopa administration decreased urinary dopamine, norepinephrine and epinephrine as expected; however, among carbidopa-treated rats urinary norepinephrine and epinephrine concentrations were highest for animals consuming the protein-free diet, again suggesting enhanced release of stored catecholamines from sympathoadrenal cells. The changes in urinary catecholamines observed in animals eating the protein-free diet were similar to those seen in rats fasted for 5 days: dopamine levels fell sharply while norepinephrine and epinephrine increased.
These data indicate that the effects of varying dietary protein and carbohydrate contents on dopamine secretion from peripheral structures differ from its effects on structures secreting the other two catecholamines. Protein consumption increases dopamine synthesis and release probably by making more of its precursor, tyrosine, available to peripheral dopamine-producing cells; it decreases urinary norepinephrine and epinephrine compared with that seen in protein-deprived animals, probably by diminishing the firing of sympathetic neurons and adrenal chromaffin cells.
Studies on the mechanism by which tyrosine raises urinary catecholamines
1982, Biochemical Pharmacology
The source of urinary catecholamines and the mechanisms by which tyrosine administration raises these compounds were investigated in rats. Adrenalectomy blocked the tyrosine-induced rise in urinary epinephrine but not dopamine or norepinephrine. Following chemical sympathectomy with 6-hydroxydopamine (6-OHDA), the tyrosine-induced increased in urinary norepiphine was diminished, but epinephrine and dopamine responses were unaffected. Cardiac norepinephrine, which is normally unchanged following tyrosine administration, became significantly elevated in 6-OHDA-pretreated animals. At the doses used in this study, tyrosine had no effect on the uptake or metabolic clearance of circulating catecholamines. We conclude that tyrosine augments the synthesis of the three catecholamines in sympathoadrenal cells by increasing the extent to which tyrosine hydroxylase is saturated with its amino acid substrate. Moreover, the effects of tyrosine on peripheral catecholamine synthesis may be enhanced under conditions of increased sympathetic activity.
Production of urine free dopamine from DOPA; A micropuncture study
1980, Life Sciences
The contribution of free L-DOPA to urinary dopamine (D) was examined by microinjecting ³H-DOPA into either proximal tubules or the peritubular space of innervated and denervated rat kidneys. Recirculation of radioactive material was corrected for by comparison with excretion of ¹⁴C inulin included in the injectate. Urine radioactivity was characterized by HPLC. 69.4 ± 2.9% of ³H-DOPA microinjected into proximal tubules appeard in urine from the ipsilateral kidney, 14.6 ± 1.6% of the ³H was recovered as D. After microinjection into the subcapsular peritubular space 4 times as much ³H appeared in the urine from the ipsilateral as from the contralateral kidney. Tubular secretion of total ³H and ³HD was calculated by comparison with ¹⁴C inulin excretion. Chronically denervated kidneys secreted 36.0 ± 4.2% of the microinjected ³H; innervated kidneys secreted 35.0 ± 3.0%. ³H-D secretion was 14.5 ± 3.7% and 15.3 ± 2.8% of the total ³H-DOPA microinjected into denervated and innervated kidneys respectively. We estimated that 30% of the urinary free D is derived from circulating free L-DOPA.

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¹: Supported by USPHS Grants AM-14228 and NS-10459 and by USPHS Training Grant AM-05371 to Dr. Hoeldtke.

²: Robert D. Hoeldtke, M.D.: Trainee in Clinical Nutrition, Department of Nutrition and Food Science, Massachusetts Institute of Technology, Cambridge, Mass.

³: Richard J. Wurtman, M.D.: Professor of Endocrinology and Metabolism, Massachusetts Institute of Technology, Cambridge, Mass.

View full text

Cereal ingestion and catecholamine excretion

Abstract

Metabolism

Arch Biochem Biophys

Anal Biochem

J Biol Chem

Life Sci

Clin Chim Acta

J Biol Chem

Dihydroxyphenylalanine in rat food containing wheat and oats

Science

Acid hydrolysis of urinary catecholamines

J Lab Clin Med

The presence of free and conjugated 3,4-dihydroxyphenylacetic acid (dopac) in urine and blood plasma

Acta Soc Med Upsal

Measurement of conjugated catecholamines in human urine

Amer J Clin Path