Lipid fluidity and composition of the erythrocyte membrane from healthy dogs and Labrador retrievers with hereditary muscular dystrophy

Anaemia in Ruminants Caused by Plant Consumption

Plant toxicology has affected animals throughout evolution. Plants have adapted themselves to the environment. This adaptation has led to the development of defensive strategies to avoid being consumed. Plants have several chemical compounds, which can cause deleterious effects on people or animals that consume them, causing a wide variety of clinical signs. Plants from various latitudes, both cultivated for human and animal feeding or decorative purpose and even wild growth plants are able to generate anaemia in ruminants. Coumarins or ptaquiloside predispose bleeding and haemorrhages, causing a haemorrhagic disease in affected animals. In this group, some important fodder plants, such sweet clover (Genus Melilotus spp.), or other weeds distributed worldwide, such as bracken fern (Pteridium aquilinum) of giant fennel (Ferula communis), are included. On the other hand, sulfur-containing chemicals (e.g., n-propyl disulfate and S-propyl cysteine sulfoxides (SMCOs)) may cause severe direct damage to the erythrocyte and their membrane, leading to their destruction and causing haemolytic anaemia in the animal. This review presents the most frequent intoxication by plants causing anaemia in ruminants. Toxic compounds, clinical signs, diagnosis and possible treatments are also presented.

The Erythrocyte Membrane Lipidome of Healthy Dogs: Creating a Benchmark of Fatty Acid Distribution and Interval Values

Molecular-based approaches are rapidly developing in medicine for the evaluation of physiological and pathological conditions and discovery of new biomarkers in prevention and therapy. Fatty acid diversity and roles in health and disease in humans are topical subjects of lipidomics. In particular, membrane fatty acid-based lipidomics provides molecular data of relevance in the study of human chronic diseases, connecting metabolic, and nutritional aspects to health conditions. In veterinary medicine, membrane lipidomics, and fatty acid profiles have not been developed yet in nutritional approaches to health and in disease conditions. Using a protocol widely tested in human profiling, in the present study erythrocyte membrane lipidome was examined in 68 clinically healthy dogs, with different ages, sex, and sizes. In particular, a cluster composed of 10 fatty acids, present in membrane glycerophospholipids and representative of structural and functional properties of cell membrane, was chosen, and quantitatively analyzed. The interval values and distribution for each fatty acid of the cluster were determined, providing the first panel describing the healthy dog lipidomic membrane profile, with interesting correlation to bodyweight increases. This molecular information can be advantageously developed as benchmark in veterinary medicine for the evaluation of metabolic and nutritional status in healthy and diseased dogs.

Effect of treatment with cadmium on structure-function relationships in rat liver mitochondria: studies on oxidative energy metabolism and lipid/phospholipids profiles

Effects of treatment with a single intraperitoneal injection of cadmium (Cd) on oxidative energy metabolism and lipid/phospholipid profiles of rat liver mitochondria were examined at the end of 1 week and 1 month. Following Cd treatment the body weight increased only in the 1 month group, whereas the liver weight increased in both groups. State 3 and 4 respiration rates in general decreased significantly, with the maximum effect being seen with succinate. The 1 week Cd group showed decreased respiratory activity with glutamate, pyruvate + malate, and succinate as the substrates. In the 1 month Cd-treated group respiration rates recovered with glutamate and pyruvate + malate but not with succinate. All cytochrome contents decreased in the 1 week Cd-treated group but recovered in the 1 month group. ATPase activity registered an increase in both Cd-treated groups. Dehydrogenase activities increased in the 1 week group but decreased in the 1 month Cd-treated group. The mitochondrial cholesterol content increased in the 1 week Cd-treated group. In the 1 week Cd-treated group the lysophospholipid (Lyso), sphingomyelin (SPM), and diphosphatidylglycerol (DPG) components increased. By contrast, the phosphatidylethanolamine (PE) component decreased. In the 1 month Cd-treated group the phosphatidylinositol, phosphatidylserine, and DPG components increased, whereas the Lyso, SPM, and phosphatidylcholine components decreased. The results demonstrate that single-dose Cd treatment can have adverse effects on liver mitochondrial oxidative energy metabolism and lipid/phosphopholipid profiles, which in turn can affect membrane structure-function relationships.

Effect of alloxan-diabetes and subsequent treatment with insulin on lipid/phospholipid composition of rat brain microsomes and mitochondria

Early and late effects of alloxan-diabetes of lipid/phospholipid composition of rat brain microsomes and mitochondria were examined. In microsomes, early as well as late diabetic stages resulted in decrease in contents of total phospholipids (TPL) and increase in cholesterol (CHL). Insulin treatment restored TPL with further increase in CHL in 1 week group. In early diabetic stage there was increase in the sphingomyelin (SPM) while phosphatidylinositol (PI) and phosphatidylserine (PS) components decreased. Insulin treatment restored SPM and decreased the lysophospholipids (Lyso), PI, PS and phosphatidic acid (PA); phosphatidylethanolamine (PE) increased. In 1 month diabetic group phosphatidylcholine (PC) decreased while PI, PS and PE increased. Insulin treatment lowered the Lyso, SPM, PI, PS and PA while PC and PE increased. In mitochondria, at early stage of diabetes both CHL and TPL contents decreased; insulin treatment restored the former component. Late diabetic stage had no effect on CHL and TPL contents; insulin treatment brought about reduction in both. Diabetic state had marginal effect on phospholipid composition at both the stages. Insulin treatment had a generalized effect of lowering of PI and PS components and increasing diphosphatidylglycerol (DPG). The fluidity of microsomal membranes decreased progressively in the diabetic condition; insulin treatment fluidized the membrane at early stage. The fluidity of mitochondrial membranes increased in early diabetic stage and the effect was accentuated by insulin treatment. However, at the late stage the effects on membrane fluidity were marginal.

Picrotoxin-induced convulsions alters rat brain microsomal membrane structural properties

Cerebral microsomal membrane properties were assessed in the chronic condition of generalized seizure induced by picrotoxin (PTX) in rats. PTX-induced seizures resulted in increased lysophosphatidyl glycerol, phosphatidylcholine and phosphatidic acid components, while phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol were significantly reduced by 19-73%. The cholesterol (CHL) content increased considerably by 25% without alteration in total phospholipids content. Microsomal membrane was more fluidized in the epileptic condition. Possible consequences of microsomal membrane alterations are discussed in terms of deregulation of Ca2+ homeostasis. In conclusion, alterations in the microsomal membrane properties may have a significant influence on the cerebral function in the chronic epileptic condition.

Structural and functional alterations in mitochondrial membrane in picrotoxin-induced epileptic rat brain

Mitochondrial function is a key determinant of both excitability and viability of neurons. Present studies were carried out to decipher cerebral mitochondrial oxidative energy metabolism and membrane function in the chronic condition of generalized seizures induced by picrotoxin (PTX) in rats. PTX-induced convulsions resulted in decreased respiration rates (14-41%) with glutamate, pyruvate + malate, and succinate as substrate. The ADP phosphorylation rates were drastically reduced by 44-65%. An opposite trend was observed with ascorbate + N,N,N',N'-tetramethyl-p-phenylenediamine [corrected] (TMPD) as substrate. In general, uncoupling of the mitochondrial electron transport was observed after PTX treatment. Malate dehydrogenase (MDH) and succinate dehydrogenase (SDH) activities were decreased by 20-80%; also, there was significant reduction in cytochrome b content after PTX treatment, while the F(o)F(1) ATPase (complex V) activity increased in basal and 2,4-dinitrophenol (DNP)-stimulated condition, indicating increased membrane fragility. The substrate kinetics analysis had shown that K(m) and V(max) of the higher affinity kinetic component of ATPase increased significantly by 1.2- to 1.4-fold in epileptic condition. Temperature kinetic analysis revealed 1.2-fold increase in energies of activation with decreased transition temperature. The total phospholipid (TPL) and cholesterol (CHL) contents decreased significantly with lowering of diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE), phosphatidylinositol (PI), and phosphatidylserine (PS), while lysophospholipid (lyso), sphingomyelin (SPM), and phosphatidylcholine components were found to be elevated. Brain mitochondrial membrane was somewhat more fluidized in epileptic animals. Possible consequences of mitochondrial respiratory chain (MRC) dysfunction are discussed. In conclusion, impairment of MRC function along with structural alterations suggests novel pathophysiological mechanisms important for chronic epileptic condition.

Effect of catecholamine depletion on oxidative energy metabolism in rat liver, brain and heart mitochondria; use of reserpine

Regulation of mitochondrial functions in vivo by catecholamines was examined indirectly by depleting the catecholamines stores by reserpine treatments of the experimental animals. Reserpine treatment resulted in decreased respiratory activity in liver and brain mitochondria with the two NAD+-linked substrates: glutamate and pyruvate + malate with succinate ATP synthesis rate decreased in liver mitochondria only. With ascorbate + TMPD system, the ADP/O ratio and ADP phosphorylation rate decreased in brain mitochondria. For the heart mitochondria, state 3 respiration rates decreased for all substrates. In the liver mitochondria basal ATPase activity decreased by 51%, but in the presence of Mg2+ and/or DNP increased significantly. In the brain and heart mitochondria ATPase activities were unchanged. The energy of activation in high temperature range increased liver mitochondrial ATPase while in brain mitochondria reserpine treatment resulted in abolishment in phase transition. Total phospholipid (TPL) content of the brain mitochondria increased by 22%. For the heart mitochondria TPL content decreased by 19% and CHL content decreased by 34%. Tissue specific differential effects were observed for the mitochondrial phospholipid composition. Liver mitochondrial membranes were more fluidized in the reserpine-treated group. The epinephrine and norepinephrine contents in the adrenals decreased by 68 and 77% after reserpine treatment.

Decreased lipid fluidity of the erythrocyte membrane in dogs with leishmaniasis-associated anaemia

In both man and the dog, anaemia resulting from natural leishmaniasis is often severe and mainly associated with a shortened life span of erythrocytes. Lipid fluidity of erythrocyte membranes from 17 dogs with anaemia caused by visceral leishmaniasis was investigated by means of fluorescence polarization. Results were compared with those from three groups of control animals (10 healthy dogs, seven dogs with visceral leishmaniasis but no anaemia, and 10 dogs with anaemia unrelated to leishmaniasis). Fluorescence polarization values recorded for animals with leishmaniasis-associated anaemia were elevated-indicating reduced erythrocyte membrane fluidity-and significantly higher than in the control groups. Mechanical sequestration by the spleen due to increased cell rigidity, or alterations in receptor/ligand erythrocyte cytoadherence mechanisms, or both, may result from decreased membrane fluidity and hence contribute to the anaemia of Leishmania -infected dogs.

Effect of aluminium-induced Alzheimer like condition on oxidative energy metabolism in rat liver, brain and heart mitochondria

Prolonged exposure of rats to aluminium (Al) can result in an Alzheimer-like condition. To get better insights into the biochemical defects underlying AD, senility and ageing we exposed rats for long durations (90-100 days) to soluble salt of aluminium (AlCl3) and checked its influence on mitochondrial respiratory activity in the liver, brain and heart. In the liver and brain mitochondria the ADP/O ratio was impaired with NAD+ linked substrates. State three respiration decreased with glutamate in the liver. For succinate, the ADP/O ratio decreased in the liver mitochondria while state three and four respiration decreased in the brain mitochondria. In both the tissues respiration rates decreased with ascorbate + TMPD as the substrate. In the heart mitochondria ADP/O ratios with NAD+ linked substrates decreased, while respiration rates increased with all the substrates except for ascorbate + TMPD. Temperature kinetics data showed different effects on ATPase in the mitochondria from the three tissues. Data on lipid/phospholipid profiles suggested that the observed changes in energy metabolism were not mediated via lipid changes. Long-term exposure to Al resulted in approximately 100% increase in Al content of liver and brain mitochondria but in the heart there was phenomenal 11-fold increase, indicating thereby that the effects of Al exposure were indirect rather than direct due to Al accumulation.

Paracetamol hepatotoxicity and microsomal function

The effect of paracetamol-induced hepatotoxicity in rats (650 mg/kg) on microsomal function was examined. Paracetamol treatment resulted in lowered Na(+),K(+)-ATPase activity in the microsomes with decrease in V(max) of the low affinity high V(max) component II. However, the temperature kinetics was not influenced significantly. The total phospholipid and cholesterol contents as well as lipid peroxidation in the microsomes were unchanged. However, content of acidic phospholipids: phosphatidylserine and phosphatidylinositol decreased by 50% with a reciprocal increase in the sphingomyelin content; the lysophosphoglyceride content increased by 12-fold. The microsomal membrane appeared to be more fluidized following paracetamol treatment. Paracetamol treatment also resulted in a significant reduction in the sulfhydryl groups content.

Thyroid hormones alter Arrhenius kinetics of succinate-2,6-dichloroindophenol reductase, and the lipid composition and membrane fluidity of rat liver mitochondria

Thyroid-status-dependent changes in lipid/phospholipid profiles in rat liver mitochondria were examined and attempts were made to correlate the observed changes with kinetic parameters of succinate-2,6-dichloroindophenol reductase (SDR) and membrane fluidity. Thyroidectomy caused substantial decrease in the total phospholipid and cholesterol contents; the proportion of all phospholipid components was also decreased significantly (50-100% decrease). The energy of activation, E1, for SDR decreased with a concomitant increase in the membrane fluidity. Treatment with physiologic doses or replacement doses of L-thyroxine resulted in partial restoration of lipid/phospholipid components. However, the SDR activity decreased with a simultaneous elevation in the phase-transition temperature and significant decreases in E1 and E2. Treatment with L-thyroxine restored membrane fluidity to almost euthyroid values. Regression analysis suggested a role for phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol microdomains in modulating the SDR activity. Membrane fluidity was strongly correlated with total phospholipid, cholesterol, diphosphatidylglycerol and phosphatidyl-inositol, and the ratio of cholesterol/total phospholipid (mol/mol).

Thyroid hormone treatment alters phospholipid composition and membrane fluidity of rat brain mitochondria

We examined effects of graded doses of thyroid hormones 3,3', 5-tri-iodo-L-thyronine (T3) and L-thyroxine (T4) on the lipid composition of rat brain mitochondria. Neither hormone significantly affected the mitochondrial cholesterol or total phospholipid content, but did increase phosphatidylethanolamine (PE) at the expense of phosphatidylserine (PS), phosphatidylinositol (PI) and phosphatidylcholine (PC). The phosphatidic acid (PA) content was also elevated, suggesting enhanced phospholipid turnover. Changes in sphingomyelin (SPM) and diphosphatidylglycerol (DPG) were minimal. Mitochondrial membrane fluidity also increased after thyroid-hormone treatment, and the increase was closely correlated with PC/PE and SPM/PE molar ratios.