Cadmium toxicity related to cysteine metabolism and glutathione levels in frog Rana ridibunda tissues

The level of glutathione and sulfane sulfur and sulfurtransferases activity in adult frogs Rana ridibunda were investigated after the exposure to 40 mg or 80 mg CdCl(2) L(-1) for 96 h or 240 h. Cd accumulation in the liver, kidneys and testes was confirmed, and the highest Cd level was found in the testes. In the liver, the exposure to Cd resulted in an increase of GSH level and the activity of rhodanese, while the activity of 3-mercaptopyruvate sulfurtransferase and cystathionase decreased. The kidneys and brain showed the elevated level of GSH and the activity of all investigated sulfurtransferases, as well as sulfane sulfur especially in brain. In such tissues as the testes, muscles and heart, the level of GSH and the activity of 3-mercaptopyruvate sulfurtransferase were significantly diminished. The increased level of sulfane sulfur was determined in the testes and muscles and the increased activity of rhodanese in the testes and the heart. These findings suggest the possible role of sulfane sulfur and/or sulfurtransferases in the antioxidation processes, which can be generated in cells by cadmium.     

Physiological significance of catalase and glutathione peroxidases,and in vivo peroxidation,in selected tissues of the toadDiscoglossus pictus (Amphibia) during acclimation to normobaric hyperoxia

1. Various parameters related to oxidative stress were measured in adult Discoglossus pictus acclimated for 15 days to either normoxia or hyperoxia (PO2 = 710 mmHg). 2. Total weight of the toads and total and relative wet weight of liver, kidneys, lungs and heart were not changed by hyperoxic acclimation. 3. In vivo tissue peroxidation increased in lung, decreased in skeletal muscle, and was not changed in liver, kidney, heart and skin after hyperoxic exposure. 4. Hyperoxic acclimation increased catalase activities in the lung, liver, kidney and heart but not in skeletal muscle and skin. 5. Liver showed higher GSH-peroxidase activity with cumene-OOH than with H2O2 as substrate, whereas lung, skeletal muscle and skin presented similar GSH-peroxidase activities with both substrates. 6. GSH-peroxidase activities did not change between hyperoxic and normoxic animals in liver, lung, skeletal muscle and skin. 7. These results show that catalase, not GSH-peroxidase, is the principal H2O2 detoxifying enzyme involved in the adaptation of D. pictus to hyperoxia.     

Effect of aminotriazole on the activity of catalase and glucose-6-phosphate dehydrogenase in tissues of two frog species--Rana ridibunda and Rana esculenta

Changes of the activity of catalase and glucose-6-phosphate dehydrogenase (G6PDH) during 48 hrs after intraperitoneal injection of 1.0, 0.5 and 0.1 mg aminotriazole per gram of body weight of two frog species as well as catalase inhibition by aminotriazole in vitro were investigated. Both aminotriazole concentration and species affiliation affected the catalase inhibition. The sensitivity of catalase from different tissues was decreased in the order: liver--kidney--lung--muscle--brain. The constant of half inhibition of lung catalase was significantly lower than that of liver and kidney catalase. The activity of G6PDH of AMT-treated frogs R. esculenta was higher comparing to control group. Possible ways of compensation of antioxidant defense under catalase inhibition are discussed.     

A study on cholesterol content in some tissues of the Saudi frog: Rana ridibunda.

1. Cholesterol content of selected tissues in the Saudi frog Rana ridibunda was determined. 2. Total cholesterol content was higher in tissues involved in water loss, ranging from 12.22 +/- 0.28 to 40.3 +/- 0.79 mg/g. 3. In tissues not involved in water loss, total cholesterol content ranged from 2.42 +/- 0.18 to 19.30 +/- 0.39 mg/g.     

Effect of light negative hydroaeroions on electromagnetic coupling of frog Rana ridibunda auricle

It is shown that negative hydroaeroions cause a decrease of the systole strength of freshly prepared auricle and activation of the tired auricle; a decrease of the amplitude and length of the heart trabecula action potentials due to depression of slow input Ca2+ current; shift of the threshold of activation of fast input Na+ current to low potentials; partly elimination of the rise of the auricle systole strength under novodrine. The latter effects were not observed under atropine and indomethacin.     

Glycolytic adjustments in tissues of frog Rana ridibunda and land snail Helix lucorum during seasonal hibernation

The present work aimed to contribute to the understanding of the adaptation of the glycolytic pathway in tissues of frog Rana ridibunda and land snail species Helix lucorum during seasonal hibernation. Moreover responses of glycolytic enzymes from cold acclimated R. ridibunda and H. lucorum were studied as well. The drop in Po₂ in the blood of hibernated frogs and land snails indicated lower oxygen consumption and a decrease in their metabolic rate. The activities of glycolytic enzymes indicated that hibernation had a differential effect on the glycolyis in the two species studied and also in the tissues of the same species. The activity of l-LDH decreased significantly in the skeletal muscle and heart of hibernated R. ridibunda indicating a low glycolytic potential. Similar biochemical responses were observed in the same tissues during cold acclimation. The continuous increase in the activities of glycolytic enzymes studied, except for HK, might indicate a compensation for the impacts of low temperature on the enzymatic activities. In contrast to R. ridibunda, the activities of the enzymes increased and remained at higher levels than those of the prehibernation controls indicating maintenance of glycolytic potential in the tissues of hibernating land snails.     

Characterization of the cDNA encoding proopiomelanocortin in the frog Rana ridibunda

In the amphibian pars intermedia, secretion of proopiomelanocortin (POMC)-derived peptides is controlled by multiple factors including classical neurotransmitters and neuropeptides. To pursue questions concerning the regulation of POMC gene expression in Rana ridibunda, we have isolated and characterized a full-length cDNA for frog POMC. A cDNA clone isolated from a frog pituitary library contains an open-reading frame of 780-bp that predicts a 260 amino acid POMC protein. The structure of frog POMC demonstrates considerable amino acid sequence similarity with POMC from other species. In particular, the sequence of alpha-melanotropin (alpha-MSH) is identical in frog and all mammalian species studied so far, while adrenocorticotropin (ACTH) and beta-endorphin exhibit 79% and 84% homology with their human counterpart. Frog POMC contains only one potential asparagine-linked N-glycosylation signal (Asn-Ser-Thr) within the gamma-MSH domain. The alpha-MSH sequence is C-terminally flanked by the Gly-Lys-Lys amidation signal while the joining peptide is not amidate.     

Effect of erythropoietin on membrane lipid peroxidation, superoxide dismutase, catalase, and glutathione peroxidase of rat RBC

Starved animals having low levels of erythropoietin in blood showed increased MDA, fluorescent pigments, and met-Hb values whereas the hemoglobin concentration decreased significantly on starvation. In vivo and in vitro studies with Ep reversed the effects of starvation and brought these values close to normal. The activities of the enzymes (SOD, catalase, GSH-PX, GR G6PD, and 6PGD) which protect the RBC membrane directly or indirectly from peroxidative threat, decreased on starvation and restored to normal levels after Ep treatment.     

Lipid peroxidation, superoxide dismutase and catalase activities in brain tumor tissues

Free radical-mediated damages may play an important role in cancerogenesis. To investigate their relevance in the cancer process, malonyl dialdehyde (MDA) level, superoxide dismutase (SOD), and catalase (CAT) activities were determined in the normal brain tissue and brain tumor tissue. When compared with the normal brain tissue, we have detected: (i) significantly lower MDA concentration in brain tumor tissue (1.63 nmol/mg Pr vs 2.04 nmol/mg Pr; p = 0.03); (ii) SOD activity in brain tumor tissue was significantly lower (3.15 U/mg Pr vs 4.97 U/mg Pr; p = 0.0002); and (iii) CAT activity in brain tumor tissue was 106.3% higher than that in controls.     

Effect of inhibitory amino acid antagonists on postsynaptic potentials of motoneurons of the frog Rana ridibunda

On preparations of the isolated spinal cord of the frog Rana ridibunda at intracellular recording from lumbar motoneurons, it is shown that response to the 10 mM GABA application decreased selectively by 40.7 ± 23.7% (n = 6) as a result of the spinal cord treatment with bicuculline (100–150 μM), while response to the Gly application decreased selectively by 50.7 ± 17.8% (n = 10) after the spinal cord treatment with strychnine (5–10 μM). Both strychnine and bicuculline produced potentiation of EPSP by amplitude and duration as well as paroxysmal depolarizational shifts (PDS). Strychnine produced more effectively the potentiation, while bicuculline—PDS. The inhibitory Gly effect decreased significantly the DR and RF EPSP (a decrease of amplitude and duration) as a result of the spinal cord treatment with strychnine (5–10 μM), but not with bicuculline. The inhibitory GABA effect on the DR and RF EPSP decreased as a result of the spinal cord treatment with bicuculline only in a half of the studied motoneurons and to the lesser degree than the inhibitory Gly effect on the same EPSP at the strychnine treatment. Based of the obtained data, it is suggested that the inhibitory effects on the excitatory inputs of the motoneuron in the frog are expressed weaker than in mammals and are related predominantly to the GABA and Gly effects on receptors of interneurons. It is suggested that GABA specifically acts mostly on GABA_A receptors, whereas Gly—on Gly receptors, although there is some part of cross-inhibition. Original Russian Text ? G. G. Kurchavyi, N. I. Kalinina, and N. P. Vesselkin, 2006, published in Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, 2006, Vol. 42, No. 5, pp. 463–471. The present work is a continuation of the work [1].     

Amplitude of miniature potentials of motor neurons in the frog Rana ridibunda

Miniature synaptic potentials have been recorded from motoneurones of the isolated spinal cord of the frog Rana ridibunda. In normal Ringer's solution, their frequency varied from 5 to 50/sec, whereas their amplitude reached 2-5 mV. Only 50-300 microV (rarely 0.5-1.5 mV) potentials persisted when TTX was added to Ringer's solution and/or Ca was replaced by Mn. However, in Ca-free solution, TTX in combination with Mn did not decrease the amplitude of miniature potentials, provided the initial values varied within 50-300 microV. Noise fluctuations did not exceed 40-50 microV, and the ratio of the number of miniature potentials of 50 microV to the number of 50 microV noise potentials was about 10:1. The observed miniature potentials with an amplitude of 50-100 microV coincide with the quantal units calculated by other authors from statistical analysis of the unitary EPSPs evoked by primary afferents or by ventrolateral tract fibers.     

In vitro and in vivo studies of potential biomarkers of lead and uranium contamination: lipid peroxidation, acetylcholinesterase, catalase and glutathione peroxidase activities in three non-mammalian species

The aim of this work was to assess the relationships between lead (Pb) and uranium (U) exposure, lipid peroxidation and some enzyme activities in a mollusc (Cohicula sp.), an earthworm (Eisenia fetida) and a fish (Brachydanio redo). A comparative shrdy was perfotmed both in vibo and in vivo on whole organism postmitochondrial fractions and four potential biomarken were analyted: a marker of neurotoxicity (acetylcholinesterase activity, AChE, EC 3.1.1.7), a marker of oxidative sbss (malondialdehyde (MDA) level), and two markers of hydroperoxide detoxication: catalase (EC 1.11.1.6) and glutathione pemxidase (GPx, EC 1.11.1.9) activities. Our results have shown that the MDA contents were not signilicantty changed by exposures to lead either in vitro or in vivo. During uranium exposure, the MDA content was increased in vitro (particularly in fish samples) whereas this metal failed to sthnulate Spid peroxidation in vivo. With some exceptions, in vitro and in vivo exposures to lead and uranium showed that the AChE, catalase and GPx acbirites were decreased in the three species. These exceptions indicated that different mechanisms occurred in the different species. In conclusion, it was shown that S9 fractions of whole organisms could be useful for environmental contamination biomonitoring. Moreover, it was shown that AChE activities wen modulated by metals in viva and cannot be considered as specific bomarken of organophosphorus or carbaw pedcide exposure. Acetylcholinesterase and catalase activieies cwld be used to survey lead and uranium contamination.     

Correlative links between superoxide dismutase, catalase and glutathione peroxidase activities in mouse liver

Qualitative and quantitative differences in correlative and regressive links between superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase were assessed in the mice liver by two- and three-dimensional statistical methods. Paired linear correlation analysis indicated SOD-CAT tandem as the correlatively acting enzymatic pair. Three-dimensional analysis revealed uniform response surfaces which exhibited higher activities at disproportional values of the other two and lower activities at proportional activities of the other two enzymes. The direct effect of the enzymes on each other was positive [table: see text] while the effect of their product was always negative.