Biomedical subjects

B Dabrowska-Bouta

Publications and source records attributed to B Dabrowska-Bouta.

8 recordsLinked to original sources

PubMed2000

Acute lead intoxication in vivo affects myelin membrane morphology and CNPase activity.

The aim of the present study was to assess the sensitivity of central nervous system myelin to acute Pb-toxicity in an animal model, that imitates lead toxicity in occupationally exposed workers, or in occasional incidents of poisoning. Our results indicated that in vivo acute lead intoxication affected both the morphology of myelin and enzymatic activity of the myelin marker, CNPase (2'3'-cyclic nucleotide 3'-phosphodiesterase). The multilayered structure of myelin sheaths was regionally disturbed, with loosely arranged membranes or ovoid-shaped swollen fragments. The activity of CNPase was diminished and Michaelis-Menten kinetics showed a decreased affinity and lower velocity of the enzyme. These data suggest that the disturbances in CNPase activity may contribute, in some extent, to the changes in myelin morphology observed in acute Pb-intoxication.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗

PubMed1999

Inhibition of dopamine transport and binding of [3H] spiperone to dopamine D2 receptor by acute Pb-toxicity in vivo.

Alterations of dopamine transport and binding of [3H] spiperone to dopamine D2 receptor following acute lead intoxication in an in vivo experimental model in adult rats imitate the acute action of Pb2+ in occupationally exposed workers or in occasional incidents of poisoning. The results show that lead-intoxication causes an increased Pb level in blood, a decrease in dopamine uptake and release in synaptosomes and affects the dopamine D2 receptor. These data show that Pb-intoxication may cause severe disturbances in the transport and receptor binding of dopamine, which is involved in the regulation of a variety of functions including locomotor activity, emotion and neuroendocrine secretion.

Acute Disease↗

PubMed1997

Lead-induced abnormalities in blood-brain barrier permeability in experimental chronic toxicity.

The aim of this paper was to determine whether prolonged drinking of lead acetate-containing water by adult rats, which imitates environmental exposure to lead (Pb), affects some morphological and biochemical properties of rat brain microvessels. We noted a significant increase of lead level in capillaries and synaptosomes obtained from brains of rats under chronic toxicity conditions. Intravenously injected horseradish peroxidase (HRP) was used to evaluate the functional state of the blood-brain barrier (BBB). The results indicate that, systematically administered at low doses, lead induces BBB dysfunction. The changes, revealed in light microscopy and confirmed by electron microscopic studies, are typical for "leaky" microvessels, reported for variety of neuropathological conditions associated with BBB damage. Enhanced pinocytotic activity of the endothelial cells and the opening of interendothelial tight junctions, together with enormous phagocytizing action of the pericytes, are the most characteristic ultrastructural features noted. The presence of specific type of perivascular cells containing droplets of lipids in the cytoplasm, together with changes in phospholipid profile in brain capillaries, suggest that altered lipid composition of membranes may, at least in part, be responsible for changes in observed membrane permeability.

Animals↗

PubMed1997

Acute lead toxicity and energy metabolism in rat brain synaptosomes.

Although the neurotoxic effects of lead (Pb) are well documented, the subcellular mechanisms of its action in the central nervous system are not fully understood. The present work examined some parameters of energy metabolism in nerve endings of the brains of adult rats exposed to Pb. We applied the model of acute Pb toxicity in vivo, imitating the acute action of lead observed in occupationally exposed workers or in occasional incidents of poisoning. The measurement of Pb levels in the synaptosomal fraction exhibited its significant accumulation under applied conditions. Oxygen consumption increased in synaptosomes from Pb-treated rats whereas the activity of cytochrome c oxidase did not change. The intrasynaptosomal levels of ATP and CrP were significantly elevated, as was the activity of creatine kinase, suggesting the activation of the CrP/CK system. On the other hand, the activity of the synaptosomal Na+,K(+)-ATP-ase decreased. We suggest that under acute Pb toxicity conditions the mobilization of CrP/CK system may take place to protect the cell against the effects of decreased Na+,K(+)-ATP-ase activity.

Animals↗

PubMed1996

Effect of acute and chronic lead exposure on the level of sulfhydryl groups in rat brain.

Lead is known to be a potent neurotoxic agent. The interactions of lead with proteins are considered to be at least one of the mechanisms due to which lead exerts its toxicity. In the present work we demonstrate that acute and chronic models of exposure to lead affected the level of total and protein-bound SH groups in homogenates and synaptosomes obtained from rat brains. The concentrations of SH groups were lowered significantly (P < 0.05) in both types of poisoning. Different classes of cellular proteins were considered to play a role in high affinity binding of lead to these ligands.

Animals↗

PubMed1996

Is lead toxicosis a reflection of altered energy metabolism in brain synaptosomes?

The aim of the experiments presented here was to discern whether prolonged consumption of leaden water, that imitates environmental exposure, affects some energetic parameters in nerve endings of adult rat brains. Our results indicated that during chronic lead intoxication the oxidation chain of synaptic mitochondria remains intact. The oxygen consumption by synaptosomes and activity of cytochrom oxidase in synaptic and pericarionic mitochondria obtained from intoxicated rats did not change in comparison to those from the control samples. Compared with the control samples, the concentration of ATP decreased and the concentration of creatine phosphate (CrP) increased drastically in fractions obtained from Pb2+ intoxicated animals with simultaneously increased activity of creatine kinase (CK). It seems likely that, the CrP/Cr/CK system constitutes a satisfactory regulatory mechanism for chronic Pb2+ toxicity effects on energy metabolism in nerve endings of the adult rats.

Adenosine Triphosphate↗

PubMedDate not supplied

Does lead provoke the peroxidation process in rat brain synaptosomes?

Up to now there has been no information concerning the effect of lead on the peroxidation process in brain nerve endings. We have examined whether lead acetate (in chronic and acute models of toxicity in vivo and in vitro) affected the level of free radicals in synaptosomes obtained from rat brain. Simultaneously, we have checked the effect of peroxidation of Pb2+ on brain homogenates and microsomal fraction. Our results indicated that the lead level in synaptosomal fraction obtained from lead-treated rats was much higher than in controls. We did not observe induction of spontaneous and Fe(3+)-dependent peroxidation either in synaptosomes or in homogenates and brain microsomes after chronic and acute lead administration to the rats. Lead itself also did not enhance both processes when added in vitro to the control brain synaptosomes in micromolar concentrations. The lack of the lead effect on the peroxidation process in subcellular fractions of brain was rather surprising, because lead is known to be the accelerator of Fe(3+)-dependent peroxidation processes in liver. Additionally, livers from rats under the same toxicity conditions were examined. We have found that lead did not provoke spontaneous peroxidation in liver, but contrary to brain fractions, it drastically increased iron-dependent peroxidation in liver homogenates and microsomes. The lack of the effect of lead on inducing peroxidation processes in brain is probably the consequence of the brain having stronger protective mechanisms against its toxicity than the liver.

Acute Disease↗

PubMedDate not supplied

Chronic lead intoxication affects the myelin membrane status in the central nervous system of adult rats.

The aim of the experiments presented here was to discern whether prolonged consumption of leaden water, which imitates an environmental exposure, affects the structure of myelin in the central nervous system of adult rats and whether the observed morphological destruction is reflected in biophysical and/or biochemical changes. The results indicated that during chronic lead (Pb) intoxication, the Pb level of the myelin fraction increases significantly. Electron microscopy studies show that myelin in control experiments is built up of ordered layers, whereas in a Pb-intoxicated sample, this order is destroyed in large areas of all preparations. Morphological disturbances in Pb-intoxicated in vivo myelin were reflected by changes in myelin membrane fluidity measured by spectrofluorometry and electron paramagnetic resonance (EPR). Prolonged Pb toxicity also caused significant changes in the morphological structure of oligodendrocytes, an increase of phosphatidylethanolamine, and decrease of protein SH group levels. Simultaneously, we found that the protein and total phospholipid content and levels of phosphatidylinositol, sphingomyelin, phosphatidyloserine, cholesterol, and the pattern of total myelin protein obtained by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in Pb-intoxicated myelin did not change compared to control values. Also, Pb intoxication did not induce peroxidation by itself and did not accelerate peroxidation produced by iron (Fe) in brain myelin.

Animals↗