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PubMed1977

delta-Aminolevulinic acid: influences on synaptic GABA receptor binding may explain CNS symptoms of porphyria.

Symptoms of acute porphyria have been attributed to effects of delta-aminolevulinic acid (ALA). We report that ALA selectively competes for the binding of tritiated gamma-aminobutyric acid ([3H]GABA) associated with synaptic GABA receptors in central nervous system membranes. Concentrations of ALA that inhibit GABA receptor binding are consistent with levels of ALA thought to exist in the central nervous system of porphyric patients. Some of the symptoms of acute porphyria resemble those elicited by muscimol, a potent GABA agonist drug. Barbiturates, which exacerbate porphyric symptoms, are potent facilitators of the synaptic actions of GABA. The results suggest that some symptoms of acute porphyria might be attributable to a mimicking by ALA of GABA at its central nervous system receptor sites.

Aminolevulinic Acid↗
PubMed1983

Inhibition of Na+, K+-ATPase activity by delta-aminolevulinic acid.

delta-Aminolaevulinic acid (ALA) has been shown to be toxic to cultured neurons and glia at concentrations as low as 10 microM. In an attempt to elucidate the mechanism of toxicity, the effects of ALA on membrane ATPase activity were investigated. Exposure of neuron cultures to 1 mM ALA for 7 days caused a substantial decrease in both Na+, K+-ATPase and Mg2+-ATPase activities. At lower concentrations, ALA affected only the Na+, K+-component. ALA appeared to act directly, inhibiting Na+, K+-ATPase activity in rat brain cortex membrane preparations at 10 microM. Although this effect was slight, it may well represent the mechanism of action of ALA, since ouabain, a potent inhibitor of Na+, K+-ATPase activity, proved to be more toxic to cultured neurons than ALA. Furthermore, cardiac glycoside overdosage causes neurological disturbances which are very similar to those observed in the acute attack of porphyria.

Adenosine Triphosphatases↗
PubMed1986

Porphyrin synthesis in primary nervous tissue cultures from 10(-3) M delta-aminolaevulinic acid in the presence of melatonin and neuropeptides.

Of the primary neuronal tissue cultures (glia cell, neuronal cells, mixed and retina cultures), the neuronal cells of (cells + medium) display the highest total porphyrin production from 10(-3) M delta-aminolaevulinic acid (ALA). In the presence of 10(-3)-10(-6) M melatonin, the quantity of total porphyrins produced by the neuronal cultures decreases in inverse proportion to the concentration. Oxytocin, lysine-vasopressin, CCK-8 sulphate ester and des-Tyr-gamma-endorphin in concentrations of 10(-5) and 10(-6) M block the porphyrin synthesis of the glia cells and display different effects on that of the neuronal cells. They enhance the total porphyrin synthesis of the cell cultures, with the exception of 10(-5) M des-Tyr-gamma-endorphin, which exerts an inhibitory effect on the glia cells.

Aminolevulinic Acid↗
PubMed1988

Inhibition of porphyrin biosynthesis by exogenous 5-aminolevulinic acid in an aerobic photosynthetic bacterium, Erythrobacter sp. OCh 114.

Exogenously administered 5-aminolevulinic acid (ALA) inhibited the formation of bacteriochlorophyll a (Bchl a) in a dose-dependent manner in the aerobic photosynthetic bacterium, Erythrobacter sp. strain OCh 114, under dark growth conditions. The ALA concentration required for half-inhibition after 24-h growth was estimated to be about 3.0 mM. Porphyrin and Bchl precursors were not found in either the cells or the growth medium. The same inhibition was also observed with cytochrome c formation. When ALA was incubated with intact cells, a large amount of ALA was converted to an unknown metabolite. The pH optimum of the conversion was 7.8. The metabolite did not react with Ehrlich's reagent, but did so with ninhydrin, giving a yellow color. Based on analyses by several techniques including mass spectrometry, ir spectrometry, and paper electrophoresis, it was identified as 4-hydroxy-5-aminovaleric acid (HAVA). Authentic HAVA prepared from ALA was a competitive inhibitor of the enzyme, porphobilinogen synthase of Erythrobacter. The Ki value for authentic HAVA was calculated to be 2.4 mM from a Dixon plot and the HAVA concentration required for half-inhibition was 17 mM. It is concluded that in Erythrobacter cells, exogenous ALA is converted to the metabolite, HAVA, which is responsible for the inhibition of porphobilinogen synthase as well as that of Bchl a and cytochrome formation.

Aminolevulinic Acid↗