Interaction between arginine vasopressin and angiotensin II receptors in the central regulation of sodium balance

We speculated that the influence of lateral preoptic area (LPO) in sodium balance, involves arginine8-vasopressin (AVP) and angiotensin (ANG II) on Na+ uptake in LPO. Therefore, the present study investigated the effects of central administration of specific AVP and ANG II antagonists (d(CH2)5-Tyr (Me)-AVP (AAVP) and [Adamanteanacetyl1, 0-ET-d-Tyr2, Val4, Aminobutyryl6, Arg(8,9)]-AVP (ATAVP) antagonists of V1 and V2 receptors of AVP. Also the effects of losartan and CGP42112A (selective ligands of the AT1 and AT2 angiotensin receptors, respectively), was investigated on Na+ uptake and renal fluid and electrolyte excretion. After an acclimatization period of 7 days, the animals were maintained under tribromoethanol (200 mg/kg body weight, intraperitonial) anesthesia and placed in a Kopf stereotaxic instrument. Stainless guide cannula was implanted into the LPO. AAVP and ATAVP injected into the LPO prior to AVP produced a reduction in the NaCl intake. Both the AT1 and AT2 ligands administered into the LPO elicited a decrease in the NaCl intake induced by AVP injected into the LPO. AVP injection into the LPO increased sodium renal excretion, but this was reduced by prior AAVP administration. The ATAVP produced a decreased in the natriuretic effect of AVP. The losartan injected into LPO previous to AVP decreased the sodium excretion and the CGP 421122A also decreased the natriuretic effect of AVP. The AVP produced an antidiuresis effect that was inhibited by prior administration into LPO of the ATAVP. The AAVP produced no change in the antidiuretic effect of AVP. These results suggest that LPO are implicated in sodium balance that is mediated by V1, V2, AT1 and AT2 receptors.     

Effect of long-term injection of high doses of potassium iodide on iodine metabolism in rat thyroid gland

Concentration of thyroid hormones in the serum of the rats after 14-day injections of potassium iodide (1, 3, 10, 100, and 500 physiological daily doses) did not differ from the control values. Excessive administration of potassium iodide increased the total iodide content in the rat thyroid tissue by 60–121% (35–108% and 94–128% for the protein-bound and free iodide, respectively), indicating the activation of the uptake and organification of iodide. The long-term injection of both low and high doses of potassium iodide increased the activity of catalase by 8–18% and SOD by 33–50% and enhanced the level of toxic LPO products reacting with thiobarbituric acid by 15–38%. It is suggested that reactive oxygen species and the excessive iodination of proteins (particularly thyroglobulin) induced by the long-term administration of high doses of potassium iodide can play an important role in the development of thyroid dysfunctions and autoimmune diseases.     

Neuroprotection by α-Lipoic Acid in Streptozotocin-Induced Diabetes

Glial cells provide structural and metabolic support for neurons, and these cells become reactive to any insult to the central nervous system. The streptozotocin (STZ) rat model was used to study glial reactivity and the prevention of gliosis by alpha-lipoic acid (alpha-LA) administration. The expression of glial fibrillary acidic protein (GFAP), S100B protein, and neuron specific enolase (NSE) was determined as well as lipid peroxidation (LPO) and glutathione (GSH) levels in some brain tissues. Western blot analyses showed GFAP, S100B, and NSE levels significantly increased under STZ-induced diabetes in brain, and LPO level increased as well. Administration of alpha-LA reduced the expression both of glial and neuronal markers. In addition, alpha-LA significantly prevented the increase in LPO levels found in diabetic rats. GSH levels were increased by the administration of alpha-LA. This study suggests that alpha-LA prevents neural injury by inhibiting oxidative stress and suppressing reactive gliosis.     

Protective Effect of Fish Oil on Changes in the Activities of Membrane-Bound ATPases and Mineral Status in Experimentally Induced Myocardial Infarction in Wistar Rats

The present study evaluated the protective effect of fish oil in isoproterenol-induced myocardial infarction in rats. The results of the present study indicate that the IPH administration decreases the activities of membrane-bound ATPases compared to control animals. Fish oil pretreatment brought about significant increase in the activity of these membrane-bound ATPases in IPH (isoproterenol hydrochloride)-treated animals. Significant increase in serum potassium level with concomitant decrease in the values of sodium, magnesium, and calcium were observed in IPH-treated rats compared to control rats, fish oil pretreatment reversed these changes to near normal. Significant elevation of sodium and calcium levels with concomitant decrease in the levels of potassium and magnesium were observed in the myocardial tissue of IPH-administered rats compared to control rats, fish oil pretreatment followed by IPH administration brought these levels to near normal. The levels of lipid peroxidation (LPO) in both serum and tissue were increased in IPH-treated rats compared with control rats, whereas pretreatment with fish oil in IPH-treated rats maintained near-normal LPO levels. The results of the present study reveals that the pretreatment of fish maintains the activities of membrane-bound ATPases and the mineral levels at near normal by the inhibition of lipid peroxidation     

Comparative-physiological study of leukocyte participation in initiation of lipid peroxidation during nitrite intoxication in rats and muskrats

The study is carried out on Wistar white rats non-adapted to oxygen deficit and on semiaquatic rodents muskrats adapted to periodic arrest of respiration during diving under conditions of Nembutal narcosis. It has been revealed that 1 h after a subcutaneous injection of sodium nitrite (3 mg/100 g body mass), intensification of lipid peroxidation (LPO) in the muskrat brain is absent, the activity of the antioxidant enzyme catalase increasing 16 times (p < 0.01) as compared with control injected with equivalent saline volume. In heart and liver, there was a statistically significant decrease of the content of LPO products active in the test with 2-thiobarbituric acid; in the femoral muscle tissue, the LPO intensity did not change. In rats, unlike muskrats, after injection of sodium nitrite, an increase of LPO is recorded in brain, while a decrease of the LPO product content in the femoral muscle; in liver the LPO intensity did not change. In muskrats, the sodium nitrite administration led to a decrease of the leukocyte spontaneous mobility, of lymphocyte cytokine-producing activity, and of neutrophil bactericidal activity (by the content of cationic proteins in neutrophilic phagocytes), whereas in rats the leukocyte mobility did not change, only the blood neutrophil bactericidal activity decreased. The ability of neutrophils to produce the superoxide anion during the nitrite intoxication did not change both in rats and in muskrats. The obtained data allow concluding that under conditions of Nembutal narcosis the leukocyte functional activity on the background of nitrite intoxication is suppressed to the greater degree in the muskrats genotypically adapted to oxygen deficit than in immunocompetent cells of the rodents not adapted to hypoxia.     

Orally Administered Lactoperoxidase Increases Expression of the FK506 Binding Protein 5 Gene in Epithelial Cells of the Small Intestine of Mice: A DNA Microarray Study

Lactoperoxidase (LPO) is a component of milk and other external secretions. To study the influence of ingested LPO on the digestive tract, we performed DNA microarray analysis of the small intestine of mice administered LPO. LPO administration upregulated 78 genes, including genes involved in metabolism, immunity, apoptosis, and the cell cycle, and downregulated nine genes, including immunity-related genes. The most upregulated gene was FK506 binding protein 5 (FKBP5), a glucocorticoid regulating immunophilin. The upregulation of this gene was confirmed by quantitative RT-PCR in other samples. In situ hybridization revealed that expression of the FKBP5 gene in the crypt epithelial cells of the small intestine was enhanced by LPO. These results suggest that ingested LPO modulates gene expression in the small intestine and especially increases FKBP5 gene expression in the epithelial cells of the intestine.     

Orally administered lactoperoxidase increases expression of the FK506 binding protein 5 gene in epithelial cells of the small intestine of mice: a DNA microarray study

Lactoperoxidase (LPO) is a component of milk and other external secretions. To study the influence of ingested LPO on the digestive tract, we performed DNA microarray analysis of the small intestine of mice administered LPO. LPO administration upregulated 78 genes, including genes involved in metabolism, immunity, apoptosis, and the cell cycle, and downregulated nine genes, including immunity-related genes. The most upregulated gene was FK506 binding protein 5 (FKBP5), a glucocorticoid regulating immunophilin. The upregulation of this gene was confirmed by quantitative RT-PCR in other samples. In situ hybridization revealed that expression of the FKBP5 gene in the crypt epithelial cells of the small intestine was enhanced by LPO. These results suggest that ingested LPO modulates gene expression in the small intestine and especially increases FKBP5 gene expression in the epithelial cells of the intestine.     

Lipid peroxidation--an initial event in experimental acute renal failure

A method was developed to monitor the occurrence of lipid peroxidation (LPO) during ischemia and Na-maleate-induced acute renal failure (ARF) on male rats in vivo by measuring malondialdehyde (MDA) levels in arterial and renal venous blood and in urine. No signs of LPO could be detected under control conditions. In ischemic ARF produced by 45 min of renal artery clamping a steep increase of MDA was found in the renal venous effluent immediately after starting reperfusion. This effect was nearly abolished after 5 min of blood reflow while glomerular filtration remained at 5% of control value during a 90-min postischemic observation period. Intoxication with Na-maleate leads to enhanced LPO in combination with an impaired renal function 2 h after administration. These findings would well explain cellular damage and some aspects of renal dysfunction associated with the initiation phase of ARF.     

Protective effect of verapamil on gastric hemorrhagic ulcers in severe atherosclerotic rats

Studies concerning with pathogenesis of gastric hemorrhage and mucosal ulceration produced in atherosclerotic rats are lacking. The aim of this study is to examine the role of gastric acid back-diffusion, mast cell histamine release, lipid peroxide (LPO) generation and mucosal microvascular permeability in modulating gastric hemorrhage and ulcer in rats with atherosclerosis induced by coadministration of vitamin D2 and cholesterol. Additionally, the protective effect of verapamil on this ulcer model was evaluated. Male Wistar rats were challenged intragastrically once daily for 9 days with 1.0 ml/kg of corn oil containing vitamin D2 and cholesterol to induce atherosclerosis. Control rats received corn oil only. After gastric surgery, rat stomachs were irrigated for 3 h with either simulated gastric juice or normal saline. Gastric acid back-diffusion, mucosal LPO generation, histamine concentration, microvascular permeability, luminal hemoglobin content and ulcer areas were determined. Elevated atherosclerotic parameters, such as serum calcium, total cholesterol and low-density lipoprotein concentration were obtained in atherosclerotic rats. Severe gastric ulcers accompanied with increased ulcerogenic factors, including gastric acid back-diffusion, histamine release, LPO generation and luminal hemoglobin content were also observed in these rats. Moreover, a positive correlation of histamine to gastric hemorrhage and to ulcer was found in those atherosclerotic rats. This hemorrhagic ulcer and various ulcerogenic parameters were dose-dependently ameliorated by daily intragastric verapamil. Atherosclerosis could produce gastric hemorrhagic ulcer via aggravation of gastric acid back-diffusion, LPO generation, histamine release and microvascular permeability that could be ameliorated by verapamil in rats.     

Elevation of blood lipid peroxide (TBA-reacting substance) level in developing chick embryos after glucocorticoid administration

When 15-day-old chick embryos were administered 0.25 mumol of hydrocortisone hemisuccinate sodium (HC) the lipid peroxides (LPO) level increased after a lag time and reached about 9-fold of control level at 48 h after the treatment. Thereafter, the amount of LPO decreased to near control level by 72 h. Data obtained by using various steroids indicated that the marked elevation of LPO in blood was related to glucocorticoid effects caused by a high dose administration. The elevation of LPO level in blood was prevented by triple administration of ascorbic acid (20 mumol/egg) at 3, 10 and 20 h after HC treatment.     

Effect of oxidative processes in lipids on the formation of the biological response during combined exposure to X-rays and chemical agents

It shown that the preliminary administration of the low toxic surfactant (Tween 80) and of acetone at low doses increases the action of the acute X-rays with sublethal and lethal doses on the living organisms. The absence of the linear dependence between the biochemical changes of the lipid peroxidation (LPO) regulatory system and initial levels of parameters of this system was found. The gain of the effect of the action on the LPO intensity in tissues and the changes in the scale and direction of the interrelation between the antioxidative status parameters in murine liver under combined exposure of the damaging factors of the chemical and physical nature was found.     

Gugulu (Commiphora mukul) induces triiodothyronine production: possible involvement of lipid peroxidation.

An investigation was made to find out the importance of gugulu (Commiphora mukul) in thyroid function of mice and to reveal the possible involvement of lipid peroxidation (LPO), if any. While no marked change in the concentrations of serum thyroxine (T4) was observed, triiodoth yronine (T3) concentration and T3/T4 ratio were enhanced following the administration of gugulu extract (0.2 g/kg b. wt./d for 15 days). A concomitant decrease in LPO was also noticed in liver, the principal site of T3 generation, suggesting that gugulu induced increase in T3 concentration is LPO mediated.     

Lipid peroxidation in the synaptosomal and mitochondrial fractions of separate brain structures in hypoxia

The paper studies intensification of lipid peroxide oxidation in separate brain structures (the medulla oblongata, cerebellum, visual and sensomotor cortex), synaptosomal and mitochondrial fractions under hypoxia. It has been established that acute hypoxia increases accumulation of lipid peroxidation (LPO) products, hydroperoxide and malonyl dialdehyde. Intensification of LPO in synaptosomes and mitochondria is more pronounced as compared to the whole structures. Preliminary treatment with antioxidants (vitamin E and ionol) considerably suppressed LPO intensity under both hypoxia and hypoxia with reoxygenation. Intensification of LPO in synaptosomes and mitochondria is suggested to be the key point in structural-functional disturbances of the nervous system under hypoxia and ischemia.     

Effect of metformin on renal microsomal proteins, lipid peroxidation and antioxidant status in dexamethasone-induced type-2 diabetic mice

An SDS-PAGE analysis of renal microsomal fraction of albino mice was performed to study the involvement of proteins in dexamethasone-induced type-2 diabetes mellitus (DM) and their alterations by metformin, a widely accepted oral antidiabetic drug. In addition, changes in renal lipid peroxidation (LPO), activities of superoxide dismutase (SOD) and catalase (CAT), reduced glutathione (GSH) content, as well as renal somatic index (RSI) and daily rate of water consumption were also investigated. While dexamethasone administration (1.0 mg/kg for 21 days) expressed two renal proteins (43 kDa and 63.23 kDa), in addition to the increased fasting serum levels of glucose and insulin, renal LPO, RSI and daily rate of water consumption, a parallel decrease in renal SOD, CAT and GSH was also observed. Treatment with metformin normalized these alterations including the renal proteins and LPO, confirming its efficacy in ameliorating dexamethasone-induced type-2 DM and also the association of two proteins with type-2 DM.     

Heme oxygenase activity in rat organs during cadmium chloride administration

Heme oxygenase activity, the level of spontaneous and ascorbat-induced LPO in the liver, kidney and spleen homogenates of rats and blood serum absorption spectrum in the Soret region in different periods both after CdCl2 and prior alpha-tocopherol administration were studied. The increase in the hemolysis products content in the serum was observed in 15 min after CdCl2 injection and remained during 24 h. Heme oxygenase activity in the liver and kidney increased after 6 h and stayed at the same level 24 h after CdCl2 administration. The level of spontaneous LPO in the spleen increased after 6 h, and in the liver and kidney the level of spontaneous and ascorbat-induced LPO increased in 24 h after CdCl2 injection. The preliminary alpha-tocopherol administration did not prevent the accumulation of hemolysis products in the serum and the increase of heme oxygenase activity in the liver and kidney caused by CdCl2 administration. However, the increase in the ascorbat-induced LPO in these organs was completely blocked. The role of heme and LPO in the heme oxygenase induction by CdCl2 are discussed.     

Enhanced free radical scavenging and decreased lipid peroxidation in the rat fetal brain after treatment with ethyl docosahexaenoate

In order to explore possible mechanisms to explain previously observed decreases in fetal brain lipid peroxidation (LPO) following intraamniotic administration of ethyl docosahexaenoate (Et-DHA) to near term fetuses, the hydroxyl radical trapping capacity of Et-DHA treated fetal brain preparations was compared to control ethyl oleate injected fetuses by electron spin resonance using 5,5'-dimethyl-1-pyrroline N-oxide (DMPO) probe. Lipid extracts from control brains showed little hydroxyl radical scavenging activity, whereas those from the Et-DHA injected animals exhibited an almost 70% decrease in the amount of DMPO-OH adducts. A marked decrease (58%) in LPO formation was noticed in the Et-DHA treated animals compared to controls. The Et-DHA treatment related trapping capacity resided in the phospholipid fraction of the lipid extract, which was enriched in both docosahexaenoic acid and aminophospholipid contents. The decreased LPO production, as well as increased production of prostaglandin E(2) and nitric oxide by the fetal brain following Et-DHA administration, could be mimicked by a synthetic quinone possessing both hydroxyl radical producing and LPO propagation inhibiting properties. The data are consistent with the possibility that the neuroprotective effect of Et-DHA might be due to possible free radical scavenging ability of the brain tissue and interference with LPO propagation.     

Anticancer potential of rhamnocitrin 4′-β-d-galactopyranoside against N-diethylnitrosamine-induced hepatocellular carcinoma in rats

The hepatoprotective activity of flavonoid rhamnocitrin 4′-β-d-galactopyranoside (RGP) obtained from leaves of Astragalus hamosus L. against N-diethylnitrosamine (DENA)-induced hepatic cancer in Wistar albino rats was evaluated. Hepatic cancer in rats was induced by single-dose intraperitoneal administration of DENA (200 mg/kg). Induction of hepatic cancer was confirmed after 7 days of DENA administration by measurement of elevated level of serum α-feto protein (AFP). Administration of DENA in a single dose lofted the levels of serum biochemical parameters like alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, total bilirubin, total protein and AFP. Antioxidant enzymes like superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and lipid per oxidation (LPO) were annealed significantly by administration of RGP in a dose-dependant manner. The histopathological examination of rat liver section was found to reinforce the biochemical observations significantly. It was observed that a substantial and dose-dependent reversal of DENA-diminished activity of antioxidant enzymes like SOD, CAT, GPx, GST and the reduced DENA-elevated level of LPO with a marked change. Any elevation in the levels of serum markers along with suppression of free radical formation by scavenging the hydroxyl radicals is significantly prevented by RGP. It also modulates the levels of LPO and perceptibly increases the endogenous antioxidant enzymes level in DENA-induced hepatocellular carcinogenesis. The findings suggest that RGP prevents hepatocellular carcinoma by suppressing the marked increase in the levels of serum marker enzymes, and suppresses the free radical by scavenging hydroxyl radicals.     

Annona squamosa seed extract in the regulation of hyperthyroidism and lipid-peroxidation in mice: Possible involvement of quercetin

Annona squamosa (Custard apple) seeds are generally thrown away as waste materials. The extract of these seeds was evaluated for its possible ameliorative effect in the regulation of hyperthyroidism in mouse model. Serum triiodothyronine (T₃), thyroxine (T₄) concentrations, hepatic glucose-6-phospatase (G-6-Pase) and 5′-mono-deiodinase (5′DI) activity were considered as the end parameters of thyroid function. Simultaneously hepatic lipid peroxidation (LPO), superoxide dismutase (SOD) and catalase (CAT) activities were investigated to observe its hepatotoxic effect, if any.

L-T₄ administration (0.5 mg/kg/d for 12 days, i.p.) increased the levels of serum T₃ and T₄, activity of hepatic G-6-Pase, 5′DI and LPO with a parallel decrease in SOD and CAT activities. However, simultaneous administration of the Annona seed extract (200 mg/kg) or quercetin (10 mg/kg) to T₄-induced hyperthyroid animals for 10 days, reversed all these effects indicating their potential in the regulation of hyperthyroidism. Further, the seed extract did not increase, but decreased the hepatic LPO suggesting its safe and antiperoxidative nature. Quercetin also decreased hepatic LPO. When relative efficacy was compared with that of propyl thiouracil (PTU), a standard antithyroidic drug, experimental seed extract appeared to be more effective. Phytochemical analyses including HPLC revealed the presence of quercetin in the seed extract and the results on the effects of quercetin suggested the involvement of this phytochemical in the mediation of antithyroidal activity of Annona squamosa seed extract.     

Effect of Bilirubin on Lipid Peroxidation, Sphingomyelinase Activity, and Apoptosis Induced by Sphingosine and UV Irradiation

The effect of bilirubin (BR) on sphingomyelin cycle activity, lipid peroxidation (LPO), and apoptosis induced by sphingosine and UV irradiation has been studied in vivo. Neutral Mg²⁺-dependent sphingomyelinase (SMase) activity and LPO level were monitored in heart, kidney, and liver of mice after administration of BR. BR inhibited both LPO and SMase activities in heart and kidney. BR induced a mild increase in LPO level and moderate increase in lipid contents in liver, consistent with the functional role of liver in both BR and lipid metabolism. BR injected to mice causes simultaneous and unidirectional alterations in both LPO level and SMase activity with a significant (p < 0.05) positive linear correlation between these two parameters. Sphingosine administration results in increased lipid peroxidation in murine liver. Data on DNA fragmentation indicate that exogenous BR may effectively protect thymus cells against sphingosine- and UV-mediated apoptosis. These results have revealed a biochemical association between oxidative stress and BR on one hand and the sphingomyelin cycle and apoptotic cell death on the other hand. Our data show that BR as an antioxidant, due to its effect on the sphingomyelin cycle, can protect membrane lipids against peroxidation and cells against apoptosis induced by various factors.     

Inhibition of DNA repair synthesis in the rat by in vivo exposure to psychotropic drugs and reversal of the effect by co-administration with alpha-tocopherol

Changes in unscheduled DNA synthesis (UDS) in lymphocytes and lipid peroxidation (LPO) in the rat brain regions cortex, hippocampus and hypothalamus were studied after 12 months of treatment with the neuroleptic fluphenazine (5 mg/kg b.w.), lithium (0.05% in drinking water), alpha-tocopherol (alpha-TP, 0.01% in drinking water) and the anticholinergic drug 7-methoxytacrine (0.1 and 1.0 g/kg in the diet). Fluphenazine and lithium suppressed UDS and increased LPO in cortex and hypothalamus. 7-Methoxy-tacrine at the lower dose stimulated UDS, at the higher dose it suppressed UDS after 6 months of exposure. Simultaneous administration of alpha-TP with fluphenazine suppressed the increase in LPO and the decrease in UDS produced by the neuroleptic alone. alpha-TP plasma levels were increased in groups administered alpha-TP as well as the levels in the hippocampus. Results indicate that the damage of biomembranes and the DNA repair enzymatic system as a consequence of fluphenazine action may be eliminated by the simultaneous administration of alpha-TP.