Male Swiss-Webster Mice Research Articles

Regulation of Phase II Enzymes by Genistein and Daidzein in Male and Female Swiss Webster Mice

The consumption of soy and soy isoflavones has been associated with a decreased risk of certain cancers. A factor contributing to this dietary chemoprevention is the activity of phase I and II biotransformation enzymes. This study evaluated the hypothesis that dietary soy isoflavones will increase hepatic and extrahepatic quinone reductase (QR), UDP-glucuronosyltransferase (UGT), and glutathione S-transferase (GST) phase II enzyme activities, under short-term feeding and basal (non-pharmacologic-induced) conditions. Male and female Swiss Webster mice were fed for 1, 3, 5, or 7 days of one of four treatments: control (casein AIN-93G) or control supplemented with flavone (positive control), genistein, or daidzein aglycones at 1,500 mg/kg of diet. QR activity was increased by daidzein in the liver, by both isoflavones in the kidney and small intestine, and by genistein in the heart. Genistein and daidzein slightly decreased UGT activities in some tissues. Liver GST activity was decreased by genistein in females. In contrast, genistein and daidzein increased kidney GST activity. In general, the greatest effects of isoflavones on phase II enzymes were observed in liver and kidney tissues, occurring at day 3, and peaking at day 5. Sex effects in the liver and kidney included females exhibiting higher QR activities and males exhibiting higher UGT and GST activities. In conclusion, individual soy isoflavones modulate phase II enzymes in mice under short-term feeding and basal conditions. This study provides insights into the actions of isolated isoflavones in mice.

Early weaning impairs body composition in male mice

This study aimed to evaluate the effect of early weaning on body composition and on parameters related to nutritional status in mice. The experimental group consisted of male Swiss Webster mice that were weaned early (at postnatal day fourteen) and fed an appropriate diet for growing rodents until postnatal day twenty-one (EW group). The control group consisted of male mice breastfed until postnatal day twenty-one (CON group). All animals were sacrificed on the twenty-first day of life. The EW group showed a decrease in liver and muscle protein content and concentration, brain protein concentration, brain DNA content and concentration, as well as liver and muscle protein/RNA ratio (p<0.05). Concerning body composition, the EW mice showed increased moisture content, increased moisture and lipid percentage, and a smaller percentage and content of protein and ash in the carcass (p<0.05). These results indicate that early weaning impairs body composition and parameters related to nutritional status, which may be explained by retarded chemical maturation processes. This data may contribute to the overall understanding of the influence of breastfeeding versus feeding with artificial milk on body composition and on nutritional status.

Imaging Vascular Endothelial Growth Factor (VEGF) Receptors in Turpentine-Induced Sterile Thigh Abscesses with Radiolabeled Single-Chain VEGF

Angiogenesis plays a central role in the pathogenesis of chronic inflammatory disorders. Vascular endothelial growth factor (VEGF) and its receptors are the most important regulators of angiogenesis. We wished to determine whether labeled forms of single-chain VEGF (scVEGF) could be used to image VEGF receptors in a well-characterized model of sterile soft-tissue inflammation induced by intramuscular injection of turpentine. Anesthetized adult male Swiss-Webster mice received a 20-microL intramuscular injection of turpentine into the right thigh. At 4, 7, or 10 d later, groups of 3-5 mice were injected via the tail vein with 50 microg of either scVEGF that had been site specifically labeled with Cy5.5 (scVEGF/Cy) or inactivated scVEGF/Cy (inVEGF/Cy) and then examined by fluorescence imaging. At 3, 4, 6, 7, 9, 10, or 12 d, additional groups of 3-5 mice were injected via the tail vein with 74-111 MBq of (99m)Tc-scVEGF (or (99m)Tc-inVEGF) and then examined by SPECT imaging. On days 3 through 10, both forms of scVEGF (scVEGF/Cy and (99m)Tc-scVEGF) showed significantly higher uptake (P < 0.05) in the right (abscessed) thigh than in the contralateral thigh (and higher uptake than the inactivated tracer). Peak uptake occurred on day 7 (3.67 +/- 1.79 [ratio of uptake in abscessed thigh to uptake in normal thigh, mean +/- SD] and 0.72 +/- 0.01 for scVEGF/Cy and inVEGF/Cy, respectively, and 3.49 +/- 1.22 and 1.04 +/- 0.41 for (99m)Tc-scVEGF and (99m)Tc-inVEGF, respectively) and slowly decreased thereafter. Autoradiography revealed peak tracer uptake in the thick irregular angiogenic rim of the abscess cavity on day 9 (5.83 x 10(-7) +/- 9.22 x 10(-8) and 5.85 x 10(-8) +/- 5.95 x 10(-8) percentage injected dose per pixel for (99m)Tc-scVEGF and (99m)Tc-inVEGF, respectively); in comparison, a thin circumscribed rim of uptake was seen with (99m)Tc-inVEGF. Immunostaining revealed that VEGFR-2 (VEGF receptor) colocalized with CD31 (endothelial cell marker) at all time points in the abscess rim, whereas F4/80 (macrophage) immunostaining reached a maximum at day 7 and decreased by day 10. The uptake of scVEGF in turpentine-induced abscesses was specific and directly related to VEGFR-2 expression in the neovasculature of the angiogenic rim. Peak tracer uptake coincided with maximum macrophage infiltration, suggesting that scVEGF imaging may be useful for the detection, localization, and monitoring of chronic inflammation in bone, joints, or soft tissues.

Mechanisms of Impaired Glucose Tolerance and Insulin Secretion during Isoflurane Anesthesia

Volatile anesthetics impair insulin secretion and glucose utilization; however, the precise mechanism of action that underlies these effects is unknown. The authors hypothesized that isoflurane inhibits glucose-induced inhibition of adenosine triphosphate-sensitive potassium channel activity in pancreatic beta cells, which could result in impaired insulin secretion and glucose tolerance. Intravenous glucose tolerance tests were performed on 28 male Japanese White rabbits anesthetized with sodium pentobarbital. Glibenclamide (50 microg/kg + 33.5 microg x kg x h) or vehicle was administered 75 min before intravenous administration of 0.6 g/kg glucose. Half of the animals (n = 7) in the vehicle and glibenclamide groups received isoflurane at 1.0 minimum alveolar concentration 30 min before administration of glucose, and the other half received a vehicle control. Hemodynamics, blood glucose, and plasma insulin were measured. A cell-attached patch clamp configuration was used to record single channel currents in the pancreas from male Swiss-Webster mice. Isoflurane alone or a combination of isoflurane and glibenclamide inhibited the insulinogenic index to a greater extent than in the vehicle and glibenclamide groups. In the patch clamp experiments, channel activity was significantly decreased as the glucose concentration was increased from 0 to 10 mm. The subsequent application of 0.5 mm isoflurane reversed the effects of glucose on channel activity. These results show that isoflurane impairs insulin secretion and glucose utilization. The mechanism of action responsible for these effects may involve a decrease in glucose-induced inhibition of adenosine triphosphate-sensitive potassium channel activity in pancreatic beta cells.

Hypoxic Preconditioning-Induced Cerebral Ischemic Tolerance

The importance of bioactive lipid signaling under physiological and pathophysiological conditions is progressively becoming recognized. The disparate distribution of sphingosine kinase (SphK) isoform activity in normal and ischemic brain, particularly the large excess of SphK2 in cerebral microvascular endothelial cells, suggests potentially unique cell- and region-specific signaling by its product sphingosine-1-phosphate. The present study sought to test the isoform-specific role of SphK as a trigger of hypoxic preconditioning (HPC)-induced ischemic tolerance. Temporal changes in microvascular SphK activity and expression were measured after HPC. The SphK inhibitor dimethylsphingosine or sphingosine analog FTY720 was administered to adult male Swiss-Webster ND4 mice before HPC. Two days later, mice underwent a 60-minute transient middle cerebral artery occlusion and at 24 hours of reperfusion, infarct volume, neurological deficit, and hemispheric edema were measured. HPC rapidly increased microvascular SphK2 protein expression (1.7+/-0.2-fold) and activity (2.5+/-0.6-fold), peaking at 2 hours, whereas SphK1 was unchanged. SphK inhibition during HPC abrogated reductions in infarct volume, neurological deficit, and ipsilateral edema in HPC-treated mice. FTY720 given 48 hours before stroke also promoted ischemic tolerance; when combined with HPC, even greater (and dimethylsphingosine-reversible) protection was noted. These findings indicate hypoxia-sensitive increases in SphK2 activity may serve as a proximal trigger that ultimately leads to sphingosine-1-phosphate-mediated alterations in gene expression that promote the ischemia-tolerant phenotype. Thus, components of this bioactive lipid signaling pathway may be suitable therapeutic targets for protecting the neurovascular unit in stroke.

Chronic treatment with sildenafil stimulates Leydig cell and testosterone secretion

The phosphodiesterase type 5 (PDE5) inhibitor, Sildenafil, is a novel, oral treatment approach for pulmonary hypertension. As Leydig cells present PDE5, this study was conducted to investigate the effects of the chronic treatment with Sildenafil (25 mg/kg) on male Swiss Webster mice steroidogenesis. After a 4-week long experimental design, Leydig cells were analysed by morphological and immunocytochemical procedures. Serum testosterone was assayed by radioimmunoassay. Leydig cells presented noteworthy ultrastructural alterations, such as a vesicular smooth endoplasmic reticulum, large vacuoles scattered through the cytoplasm, enlarged mitochondria with discontinue cristaes and whorle membranes with vesicles at the periphery, which are typical characteristics of an activated steroid-secreting cell. Important immunocytochemical labelling for steroidogenic acute regulatory protein, cytochrome P450 side-chain cleavage enzyme and testosterone were detected in isolated Leydig cells. In addition, Sildenafil-treated mice showed significant increased levels of total testosterone. The results obtained in the present study are consistent with the hypothesis that the accumulation of cyclic guanosine monophosphate by PDE5 inhibition could be involved in the androgen biosynthesis stimulation. Important clinical implications of hormonal disorders should be taken into account for patients with pulmonary hypertension.

Influence of light at night on murine anxiety- and depressive-like responses

Individuals are increasingly exposed to light at night. Exposure to constant light (LL) disrupts circadian rhythms of locomotor activity, body temperature, hormones, and the sleep-wake cycle in animals. Other behavioural responses to LL have been reported, but are inconsistent. The present experiment sought to determine whether LL produces changes in affective responses and whether behavioural changes are mediated by alterations in glucocorticoid concentrations. Relative to conspecifics maintained in a light/dark cycle (LD, 16:8 light/dark), male Swiss-Webster mice exposed to LL for three weeks increased depressive-like behavioural responses as evaluated by the forced swim test and sucrose anhedonia. Furthermore, providing a light escape tube reversed the effects of LL in the forced swim test. LL mice displayed reduced anxiety as evaluated by the open field and elevated-plus maze. Glucocorticoid concentrations were reduced in the LL group suggesting that the affective behavioural responses to LL are not the result of elevated corticosterone. Additionally, mice housed in LD with a clear tube displayed increased paired testes mass as compared to LL mice. Taken together, these data provide evidence that exposure to unnatural lighting can induce significant changes in affect, increasing depressive-like and decreasing anxiety-like responses.

Malaria downmodulates mRNA expression and catalytic activities of CYP1A2, 2E1 and 3A11 in mouse liver

It has been reported that malaria reduces cytochrome-P450 (CYP) content and monooxygenase activities in the mammalian host liver. The mechanism by which malaria modulates CYP activities, however, remains unclear. In this study we found that activities of ethoxy- and benzyloxy-resorufin- O-dealkylases, p-nitrophenol-hydroxylase and erythromycin- N-demethylase (mediated by CYP1A, 2B, 2E1 and 3A, respectively) were depressed, while uridine-glucuronosyl-transferase (a phase 2 enzyme) was unaltered in liver microsomes of Plasmodium berghei-infected (parasitemia > 20%) male Swiss Webster mice. Prolongation of midazolam sleeping time and a slower clearance of chlorzoxazone were also noted in infected mice. Reductions of hepatic levels of CYP1A2, 2E1 and 3A11 mRNAs indicated that malaria downregulated these CYP-mediated activities at a pre-translational level.

CM156, A Sigma (σ) Receptor Antagonist, Mitigates Stimulant And Neurotoxic Effects Of Methamphetamine In Mice

Methamphetamine (METH) is a psychostimulant drug of abuse, causing hyperthermia and neurotoxicity at high doses. Currently, there is no clinically proven pharmacotherapy to treat these effects. Therefore, there is a need to identify potential therapeutic targets. Radioligand binding assays showed that METH binds to sigma (σ) receptors in the brain. Antisense oligonucleotides targeting σ1 receptors antagonized the locomotor stimulant effects of METH in mice. As a potential pharmacological antagonist, CM156 was developed with high affinity and selectivity for σreceptors. CM156 antagonized the locomotor stimulant effects of METH without altering basal activity. CM156 was further tested against METH‐induced neurotoxicity, whereby male Swiss Webster mice were treated every 2 hours, a total of 4 times, with one of the following: Saline/Saline, Saline/METH (1.25‐10 mg/kg), CM156 (5‐20 mg/kg)/Saline, and CM156 (5‐20 mg/kg)/METH (5‐10 mg/kg). Body temperature was measured 1 hour after every treatment and the brains were collected for ELISA and immunohistochemical analyses one week later. CM156 significantly and dose dependently attenuated the METH‐induced hyperthermia, depletions in striatal dopamine and serotonin levels, and reductions in DAT levels, without itself causing any changes. Together, the data suggest that σreceptors represent a viable therapeutic target for mitigating METH effects.(Support: DA023205, DA013978)

Intranasal administration of mouse [D-Leu-4]OB3, a synthetic peptide amide with leptin-like activity, enhances total uptake and bioavailability in Swiss Webster mice when compared to intraperitoneal, subcutaneous, and intramuscular delivery systems

Using a synthetic peptide strategy, we localized an active domain in mouse leptin to a sequence between amino acids 106 and 140. Intraperitoneal (ip) administration of a number of synthetic peptide amides encompassed by this domain reduced body weight gain, food and water intake, blood glucose levels, and increased insulin sensitivity in genetically obese mice. In the present study, we examined the pharmacokinetics of mouse [D-Leu-4]OB3, our most potent peptide, in male Swiss Webster mice following ip, subcutaneous (sc), and intramuscular (im) injection, and after intranasal administration with Intravail®, a new class of patented transmucosal delivery enhancement agents. Total uptake (1,072,270, 1,182,498; 1,481,060; ng/ml/min), serum half-life (48.8; 34.0; 30.0 min) and relative bioavailability (1.0, 1.1; 1.4;) of mouse [D-Leu-4]OB3 were similar when the peptide was given by ip, sc, or im injection, respectively. Total uptake and relative bioavailability were enhanced following intranasal delivery (4,336,963 ng/ml/min and 4.0, respectively), and serum half-life was 41.1 min. These results indicate that intranasal delivery of mouse [D-Leu-4]OB3 with Intravail® is a more effective method of peptide administration than injection methods, and suggest that it may have potential as a novel, non-invasive approach to the treatment of obesity and its associated metabolic dysfunctions in humans.

AUMENTO DA EXPRESSÃO DE ?-CATENINA E CADERINA NO CORAÇÃO DE CAMUNDONGOS NA FASE AGUDA E CRÔNICA DA INFECÇÃO EXPERIMENTAL POR Trypanosoma cruzi

Adherens junctions proteins have also been envolved in pathological mechanism of chagasic myocardiopathy. Aimed to determine the nature of these alterations, ten Swiss Webster male mice, 25 days-old were infected with a Type III strain of Trypanosoma cruzi through intraperitoneal (IP) route with 1.0 x 104 trypomastigotes/mouse. Five infected mice were killed at 14th day (parasitemia peak) of infection (group A). Another five infected mice (group C), were killed three months after inoculation, representing the chronic phase of the infection. Ten mice were injected through IP route with sterile 0.9% sodium chloride solution and were maintained under the same general conditions of the other groups. Five mice were killed either on day 14 (group CA) and five were killed at the end of the third month (group CC), and served as uninfected controls. Adherens junctions were analyzed by total lysate of the hearts that were immunoblotted for pan-cadherin and β-catenin. Western blot analysis revealed increases of cadherins in both acute (2.1-fold ± 0.89, p= 0.048) and chronic (2.1-fold ± 0.92, p= 0.05) phase versus its respective controls. In relation to β-catenin the results showed the same pattern characterized by increases in its levels also in acute (6.8-fold ± 4.65, p= 0.047) and chronic (3.65-fold ± 1.93, p= 0.033) phase in relation to controls. Thus, these results point to the evolvement of adherens junction proteins with pathological events in hearts of mice infected with T. cruzi infection. KEY WORDS: Adherens junctions, Chagas disease, myocarditis, western blotting.

The Effects of Lamotrigine on the Acquisition and Expression of Morphine-Induced Place Preference in Mice

The purpose of the present study is to determine the effects of the anticonvulsant drug, lamotrigine, on the acquisition and expression of morphine-induced place preference in mice. Lamotrigine prevents the release of glutamate from presynaptic neurons and inhibits action potential in postsynaptic area by inhibiting presynaptic sodium and calcium channels. Because of such properties, lamotrigine is used for reducing craving for and use of cocaine, alcohol and abused inhalant. So, to determine the effects of lamotrigine on opiates; specifically morphine, 180 male Swiss-Webster mice (20-35 g) were used in this study. Conditioned place preference, was assessed using a biased place conditioning paradigm. In a pilot study the effects of various doses of morphine (2.5, 5 and 10 mg kg(-1)), alone, or in combination with lamotrigine (1, 5 and 25 mg kg(-1)) on the place conditioning paradigm were examined. Animals were injected with the aforementioned doses of lamotrigine 60 min either prior to each morphine injections (acquisition) or prior to the start of the expression on the test day (expression). Administration of different doses of morphine (2.5, 5 and 10 mg kg(-1)) induced conditioned place preference whereas the administration of different doses of lamotrigine (1, 5 and 25 mg kg(-1)) failed to induce place preference. Acquisition and expression of morphine-induced CPP were reduced by lamotrigine at doses of 1, 5 and 25 mg kg(-1) and 5 and 25 mg kg(-1), respectively. Physiological mechanisms of action of lamotrigine and its potential therapeutic use in the treatment of drug-dependence are discussed.

Glucocorticoid‐induced bone loss in mice can be reversed by the actions of parathyroid hormone and risedronate on different pathways for bone formation and mineralization

Glucocorticoid excess decreases bone mineralization and microarchitecture and leads to reduced bone strength. Both anabolic (parathyroid hormone [PTH]) and antiresorptive agents are used to prevent and treat glucocorticoid-induced bone loss, yet these bone-active agents alter bone turnover by very different mechanisms. This study was undertaken to determine how PTH and risedronate alter bone quality following glucocorticoid excess. Five-month-old male Swiss-Webster mice were treated with the glucocorticoid prednisolone (5 mg/kg in a 60-day slow-release pellet) or placebo. From day 28 to day 56, 2 groups of glucocorticoid-treated animals received either PTH (5 microg/kg) or risedronate (5 microg/kg) 5 times per week. Bone quality and quantity were measured using x-ray tomography for the degree of bone mineralization, microfocal computed tomography for bone microarchitecture, compression testing for trabecular bone strength, and biochemistry and histomorphometry for bone turnover. In addition, real-time polymerase chain reaction (PCR) and immunohistochemistry were performed to monitor the expression of several key genes regulating Wnt signaling (bone formation) and mineralization. Compared with placebo, glucocorticoid treatment decreased trabecular bone volume (bone volume/total volume [BV/TV]) and serum osteocalcin, but increased serum CTX and osteoclast surface, with a peak at day 28. Glucocorticoids plus PTH increased BV/TV, and glucocorticoids plus risedronate restored BV/TV to placebo levels after 28 days. The average degree of bone mineralization was decreased after glucocorticoid treatment (-27%), but was restored to placebo levels after treatment with glucocorticoids plus risedronate or glucocorticoids plus PTH. On day 56, RT-PCR revealed that expression of genes that inhibit bone mineralization (Dmp1 and Phex) was increased by continuous exposure to glucocorticoids and glucocorticoids plus PTH and decreased by glucocorticoids plus risedronate, compared with placebo. Wnt signaling antagonists Dkk-1, Sost, and Wif1 were up-regulated by glucocorticoid treatment but down-regulated after glucocorticoid plus PTH treatment. Immunohistochemistry of bone sections showed that glucocorticoids increased N-terminal Dmp-1 staining while PTH treatment increased both N- and C-terminal Dmp-1 staining around osteocytes. Our findings indicate that both PTH and risedronate improve bone mass, degree of bone mineralization, and bone strength in glucocorticoid-treated mice, and that PTH increases bone formation while risedronate reverses the deterioration of bone mineralization.

Acamprosate attenuates the handling induced convulsions during alcohol withdrawal in Swiss Webster mice

In the present study, we examined the effects of acamprosate for its ability to reduce handling induced convulsions (HICs) during alcohol withdrawal. Diazepam was used as a positive control. Swiss Webster male mice received three daily IP injections of alcohol (2.5 g/kg) or alcohol (2.5 g/kg) + methylpyrazole (4-MP) (9 mg/kg). (4-MP, being an alcohol dehydrogenase inhibitor slows down the breakdown of alcohol. 4-MP in combination with alcohol exhibits a dramatic increase in blood alcohol level compared to alcohol alone). Ten hours following the last alcohol injection, the mice were picked up by the tail and examined for their seizure susceptibility (HICs). Diazepam, a benzodiazepine known to reduce seizures during alcohol withdrawal, significantly reduced these HICs at doses of 0.25, 0.5 and 1 mg/kg ( p's < 0.001). Acamprosate, an anti-relapse compound used clinically in newly abstinent alcoholics, also reduced these HICs at doses of 100, 200 and 300 mg/kg ( p's < 0.05). This study supports the use of acamprosate during periods of alcohol withdrawal as well as during abstinence.

Nonalcoholic steatohepatitic (NASH) mice are protected from higher hepatotoxicity of acetaminophen upon induction of PPARα with clofibrate

The objective was to investigate if the hepatotoxic sensitivity in nonalcoholic steatohepatitic mice to acetaminophen (APAP) is due to downregulation of nuclear receptor PPARα via lower cell division and tissue repair. Male Swiss Webster mice fed methionine and choline deficient diet for 31 days exhibited NASH. On the 32nd day, a marginally toxic dose of APAP (360 mg/kg, ip) yielded 70% mortality in steatohepatitic mice, while all non steatohepatitic mice receiving the same dose survived. 14C-APAP covalent binding, CYP2E1 protein, and enzyme activity did not differ from the controls, obviating increased APAP bioactivation as the cause of amplified APAP hepatotoxicity. Liver injury progressed only in steatohepatitic livers between 6 and 24 h. Cell division and tissue repair assessed by 3H-thymidine incorporation and PCNA were inhibited only in the steatohepatitic mice given APAP suggesting that higher sensitivity of NASH liver to APAP-induced hepatotoxicity was due to lower tissue repair. The hypothesis that impeded liver tissue repair in steatohepatitic mice was due to downregulation of PPARα was tested. PPARα was downregulated in NASH. To investigate whether downregulation of PPARα in NASH is the critical mechanism of compromised liver tissue repair, PPARα was induced in steatohepatitic mice with clofibrate (250 mg/kg for 3 days, ip) before injecting APAP. All clofibrate pretreated steatohepatitic mice receiving APAP exhibited lower liver injury, which did not progress and the mice survived. The protection was not due to lower bioactivation of APAP but due to higher liver tissue repair. These findings suggest that inadequate PPARα expression in steatohepatitic mice sensitizes them to APAP hepatotoxicity.

Effects of Pyridine Exposure upon Structural Lipid Metabolism in Swiss Webster Mice

Pyridine is a prototypical inducer of cytochrome P450 (CYP) 2E1, an enzyme associated with cellular oxidative stress and membrane damage. To better understand the effect of this treatment on cellular lipids, the influence of pyridine exposure (100 mg/kg/day i.p. for 5 days) on fatty acids, fatty esters, and fatty alcohol ethers in brain, heart, liver, and adipose tissue from male Swiss Webster mice was investigated. Lipid levels in cholesterol esters, triglycerides, free fatty acids, cardiolipin, sphingomyelin, and glycerylphospholipids were quantified. Pyridine altered the level and composition of lipids involved in membrane structure (i.e., sphingomyelin, phosphatidylethanolamines, and plasmalogens), energy metabolism (i.e., free fatty acids), and long-chain fatty acid transport (i.e., cholesterol esters) in a tissue-specific manner. Subtle changes in cholesterol esters were observed in all tissues. Sphingomyelin in the brain and heart were depleted in monounsaturated fatty acids (1.4- and 1.5-fold, respectively), while the liver sphingomyelin concentrations increased (1.5-fold). Pyridine exposure also increased heart free fatty acids by 1.3-fold, enriched cardiac phosphatidylethanolamine in long-chain polyunsaturated fatty acids by 1.3-fold, and depleted cardiolipin-associated plasmalogens by 3.8-fold. Phosphatidylethanolamines in the brain were also enriched in both saturated fatty acids (1.2-fold) and polyunsaturated fatty acids (1.3-fold) but were depleted in plasmalogens (2.9-fold). In particular, the levels of phosphatidylethanolamine-associated arachidonic (AA) and docosahexaenoic acid (DHA) in both brain and cardiac tissues significantly decreased following pyridine exposure. Considering the hypothetical role of plasmalogens as membrane-bound reactive oxygen scavengers, the current findings suggest that the brain and heart should be the focus of future studies on the toxicity of pyridine, as well as other CYP 2E1 inducers.

Hemoglobin and albumin adducts of naphthalene-1,2-oxide, 1,2-naphthoquinone and 1,4-naphthoquinone in Swiss Webster mice

The toxicity of naphthalene in rodents has been attributed to the reactive metabolites naphthalene-1,2-oxide (NPO), 1,2-naphthoquinone (1,2-NPQ) and 1,4-naphthoquinone (1,4-NPQ). Differences in the formation of these reactive metabolites in different species can shed light on the mechanism by which naphthalene exerts its toxicity. Protein adducts allow investigators to study the disposition of reactive metabolites that cannot be measured directly. We measured cysteinyl adducts of the above metabolites in hemoglobin (Hb) and albumin (Alb) from the blood of male Swiss Webster mice dosed with 1.56–200 mg naphthalene/kg b.w. Levels of NPO adducts (designated as NPO1-Hb, NPO2-Hb, NPO1-Alb and NPO2-Alb) increased nonlinearly with the administered dose; levels of Alb adducts were higher than those of Hb adducts; levels of NPO1 adducts were higher than those of NPO2 adducts. Levels of NPQ adducts (1,2-NPQ-Alb, 1,4-NPQ-Alb, 1,2-NPQ-Hb and 1,4-NPQ-Hb) were lower than those of NPO. Although NPQ-Alb increased with doses above 12.5 mg naphthalene/kg body wt. (b.w.), levels of NPQ-Hb barely increased above the background levels within the dose range examined. The shapes of the dose response curves for total cysteinyl adducts (combined NPO and NPQ) in Hb and Alb were consistent with previous results of radiobinding experiments in naphthalene-dosed mice. Dose-specific levels of NPO-Alb remained essentially constant in mice over the dose range of 25–200 mg/kg b.w. while those of 1,2- and 1,4-NPQ-Alb diminished over this range. Comparing dose-specific levels of NPO-Alb in Swiss Webster mice with those published previously in F344 rats suggests that glutathione depletion in mice occurred at about 1/8th the administered dose previously observed in rats. This suggests that mice could be more susceptible than rats to the toxic effects of naphthalene due to more pronounced depletion of glutathione at a given dose.

The rewarding effect of aggression is reduced by nucleus accumbens dopamine receptor antagonism in mice

Dopamine (DA) receptors within the nucleus accumbens (NAc) are implicated in the rewarding properties of stimuli. Aggressive behavior can be reinforcing but the involvement of NAc DA in the reinforcing effects of aggression has yet to be demonstrated. To microinject DA receptor antagonists into the NAc to dissociate their effects on reinforcement from their effects on aggressive behavior and general movement. Male Swiss Webster mice were implanted with guide cannulae aimed for the NAc and tested for aggressive behavior in a resident-intruder procedure. Aggressive mice were then conditioned on a variable-ratio 5 (VR-5) schedule with presentation of the intruder as the reinforcing event. The D1- and D2-like receptor antagonists SCH-23390 and sulpiride were microinfused (12-50 ng) before the mice responded on the VR-5 schedule and attacked the intruder. Open-field activity was also determined following the highest doses of these drugs. SCH-23390 and sulpiride dose-dependently reduced VR responding but did not affect open-field activity. The 50-ng SCH-23390 dose suppressed response rates by 40% and biting behaviors by 10%; other aggressive behaviors were not affected. The 25 and 50 ng sulpiride doses almost completely inhibited VR responding; the 50-ng dose suppressed biting by 50%. These results suggest that both D1- and D2-like receptors in the ventral striatum are involved in the rewarding properties of aggression, but that D1-like receptors may be related to the motivation to earn reinforcement as opposed to aggressive behavior.

Antiplatelet aggregation of garlic (Alliun sativum L.) water extract, turmeric (Curcuma domestica Val.) ethanolic extract and its combination to Swiss Webster male mice

Antiplatelet aggregation effect of garlic (Allium sativum L.) water extract, turmeric (Curcuma domestica Val.) ethanolic extract and its combination to Swiss Webster mice has been investigated. The test substances given orally during the period of 28 days. Antiplatelet aggregation effect was tested by measuring bleeding time, coagulation time, and decreasing plasma absorbance to observe platelet aggregation activity before and after addition of ADP as platelet aggregation inducer. Based on the inhibition of plasma abdorbance decrease, turmeric extract at a dose of 100 mg/kg body weight, garlic extract at a dose of 100 mg/kg body weight, combination of turmeric at a dose of 100 mg/kg body weight and garlic extract at a dose of 100 mg/kg body weight as well as combination of turmeric at a dose of 50 mg/kg body weight and garlic extract at a dose of 50 mg/kg body weight showed the effect of platelet aggregation inhibition of 73.67 ± 10.30% (p=0.021); 74.67 ± 25.04% (p=0.018); 77.43 ± 8.09% (p=0.018); and 57.00 ± 23.87% (p=0.047) respectively. The test substances above respectively increased bleeding time of 473.08 ± 56.12% (p<0.000); 427.53 ± 66.89% (p<0.000); 515.73 ± 114.47% (p= 0.001); 481.73 ± 116.51% (p=0.001). Increasing coagulation time only showed by combination of turmeric and garlic extract at a dose of each 100 mg/kg body weight and also of each 50 mg/kg body weight with percentage of 46.67 ± 21.89% (p=0.014) and 40.84 ± 25.80% (p=0.018). Key words : Antiplatelet aggregation, turmeric, garlic, ADP.

Nitric oxide reverses prednisolone-induced inactivation of muscle satellite cells

Long-term corticosteroid therapy causes myopathy and can inhibit regeneration of skeletal muscle. Therefore, we hypothesized that corticosteroid exposure reduces satellite cell activity in skeletal myofibers. Male Swiss-Webster mice were injected daily for 8 weeks with prednisolone (GC) or vehicle (control). Single myofibers were isolated from the gastrocnemius, centrifuged to mechanically activate satellite cells, and maintained in culture for 48 h. Both constitutive nitric oxide synthase (NOS) isoforms were reduced in muscle by GC treatment (nNOS: -30%, eNOS: -34%). Fewer myogenic (myoD+) cells emanated from GC myofibers compared to control (-61%, P < 0.05). Supplementation of culture media with the nitric oxide donor, diethylenetriamine NONOate (DETA-NO; 5-50 microM), caused a dose-dependent increase in the number of myoD+ cells arising from both control and GC myofibers (P < 0.05), and 10 and 50 microM DETA-NO eliminated the GC-induced deficit in myogenic cells (P > 0.05). Therefore, supplementation of GC myofibers with DETA-NO restores satellite cell activity to control levels. Nitric oxide production could be an important therapeutic target for the prevention of corticosteroid myopathy.