Ethanol inhibits δ-aminolevulinate dehydratase and glutathione peroxidase activities in mice liver: Protective effects of ebselen and N-acetylcysteine

Changes in sulfhydryl status have been shown to be involved with the ethanol-induced hepatotoxicity. In addition, evidence shows the importance of replenishing thiols in patients with alcoholic liver disease. This study was undertaken to examine the possible beneficial effects of the individual and simultaneous treatments with two antioxidant drugs (N-acetylcysteine and ebselen) against ethanol-induced changes in thiol status, as well as on the activities of δ-aminolevulinate dehydratase (δ-ALA-D) and glutathione peroxidase (GPx) in mice liver. Daily ethanol administrations (3 g ethanol/kg, by gavage) decreased liver nonprotein thiols (NPSH) concentration after 30 days of treatment and N-acetylcysteine (300 mg/kg once a day, i.p.) or ebselen (5 mg/kg once a day, subcutaneously) treatment restored this variable to control levels. However, additive beneficial effects concerning NPSH levels were not observed after the simultaneous administration with both drugs. While liver GPx and δ-ALA-D activities were inhibited by ethanol exposure and these inhibitions were significantly blunted by N-acetylcysteine or ebselen treatment, the simultaneous administration with both drugs did not show additive beneficial effects in relation to the enzymes’ activities. NPSH levels were positively correlated with GPx and δ-ALA-D activities. The results presented herein show that ebselen and N-acetylcysteine alone are able to restore ethanol-induced thiols as well as the inhibition of hepatic enzymes whose catalytic functions depend on their thiol (δ-ALA-D) and selenol (GPx) groups.     

Evaluation of acute effects of melatonin on ethanol drinking in ethanol na?ve rats

Objective:

The objective was to evaluate the acute effect of melatonin on ethanol drinking in ethanol naïve rats and to determine the specificity of the effect of melatonin on ethanol intake as compared to an intake of plain tap water or sugar water.

Materials and Methods:

A total of three experiments (2 weeks duration each) using different drinking solutions (ethanol, plain tap water, sugar water) was conducted in individually housed male wistar rats of 5 weeks age. Each animal had access to bottles containing drinking solutions for 2 h a day. In each experiment, on day 1, day 2, day 4, day 5, day 8, day 9, day 11, day 12 rats received drinking solutions. Each individual rat received single doses of saline, melatonin (50 mg and 100 mg/kg), and naltrexone on day 2, 5, 9, and 12, 1-h before receiving drinking solution. The order of drug administration is permuted such a way that each animal received the drugs in a different order in different experiments.

Results:

Melatonin has significantly decreased ethanol consumption by the rats and effect is dose-dependent. Naltrexone also has caused a significant reduction in the ethanol consumption. The maximum reduction in ethanol consumption was seen with melatonin 100 mg/kg dose compared to melatonin 50 mg/kg and naltrexone. There was no statistically significant effect of melatonin on plain water and sugar solution intake.

Conclusions:

Melatonin decreases ethanol consumption in ethanol naïve rats. The effect of melatonin is similar to naltrexone affecting selectively ethanol consumption, but not plain water and sugar water consumption.KEY WORDS: Dependence, ethanol, melatonin, naltrexone     

The metabolic fate and effects of 2-Bromophenol in male Sprague–Dawley rats

Abstract

1. The metabolic fate and urinary excretion of 2-bromophenol, a phenolic metabolite of bromobenzene, was investigated in male Sprague–Dawley rats following single intraperitoneal doses at either 0, 100, or 200?mg/kg.

2. Urine was collected for seven days and samples analysed using ^1?H NMR spectroscopy, inductively coupled plasma (ICP)MS, and UPLC-MS.

3. ^1?H NMR spectroscopy of the urine samples showed that, at these doses, 2-bromophenol had little effect on endogenous metabolite profiles, supporting histopathology and clinical chemistry data, which showed no changes associated with the administration of 2-bromophenol in this study.

4. The use of ICP-MS provided a means for the selective detection and quantification of bromine-containing species and showed that between 15 and 30% of the dose was excreted via the urine over 7?days of the study for both the 100 and 200?mg doses, respectively.

5. The bulk of the excretion of Br-containing material had occurred by 8?h post administration. UPLC-MS of urine revealed a number of metabolites of 2-bromophenol, with 2-bromophenol glucuronide and 2-bromophenol sulphate identified as the major species. A number of minor hydroxylated metabolites were also detected as their glucuronide, sulphate, or O-methyl conjugates. There was no evidence for the production of reactive metabolites.     

The potential therapeutic effects of baicalein and breviscapine on the vascular dementia of rats

Baicalein and breviscapine are traditional Chinese medicines and are extensively used in clinic to treat cardiovascular diseases and cerebrovascular injury. In a series of studies, we demonstrated that both of them have therapeutic effects on cognitive impairment and neuronal degeneration in a rat model of chronic cerebral hypoperfusion induced by permanent occlusion of bilateral common carotid arteries （2VO）.     

The effects of dopamine D1 and D2 receptor antagonists on the rewarding effects of δ1 and δ2 opioid receptor agonists in mice

The effects of the dopamin D₁ antagonist SCH23390 and the D₂ antagonist sulpiride on the rewarding effects of opioid receptor agonists were examined in mice. Both [d-Pen², Pen⁵]enkephalin (DPDPE, 1–15 nmol, ICV), a selective ₁ opioid receptor agonist, and [d-Ala²]deltorphin II (DELT, 0.5–5 nmol, ICV), a selective ₂ opioid receptor agonist, produced a dose-dependent place preference in mice. The DPDPE (15 nmol, ICV)-induced place preference was abolished by BNTX (0.5 mg/kg, SC), a ₁ opioid receptor antagonist, but not by NTB (0.5 mg/kg, SC), a ₂ opioid receptor antagonist. In contrast, the DELT (5 nmol, ICV)-induced place preference was antagonized by NTB, but not BNTX. Pretreatment with SCH23390 (3 µg/kg, SC) abolished the DPDPE-induced place preference, but not affect the DELT-induced place preference. Moreover, pretreatment with sulpiride (40 mg/kg, SC) did not modify the place preference induced by DPDPE or DELT. In the present study, we found that the activation of both central ₁ and ₂ opioid receptors produced rewarding effects. Furthermore, these results suggest that the rewarding effects of ₁ opioid receptor agonist may be produced through activation of the central dopaminergic system, especially dopamine D₁ receptors, whereas the rewarding effects of ₂ opioid receptor agonists may be produced by some other mechanism(s).     

Dissociation between sex differences in the immunological, behavioral, and physiological effects of κ- and δ-opioids in Fischer rats

Rationale The sex of the individual can have a profound effect on sensitivity to the effects of opioids. Recently, our laboratory provided the first evidence that females may be more sensitive to the immune-altering effects of μ-opioids than males. However, it remains unknown whether κ- and δ-opioids produce sexually dimorphic effects on immune responses. Objective The present study sought to determine whether κ- and δ-opioids produce differential immunological effects in males and females using the memory-T-cell-dependent in vivo inflammatory response contact hypersensitivity (CHS). As sex differences in the magnitude of opioid effects can be outcome-specific, additional experiments were conducted to compare the immunological effects of κ- and δ-opioids with other behavioral and physiological effects. Materials and methods Contact hypersensitivity was induced in male and female Fischer rats. Prior to elicitation of CHS, animals were administered selected doses of the κ-opioid spiradoline (0.2–20 mg/kg), δ-opioid SNC80 (1–10 mg/kg), or vehicle. The antinociceptive and diuretic effects of spiradoline were also assessed in males and females, as were the locomotor effects of SNC80. Results Spiradoline produced significantly greater enhancement of CHS in females than males, but produced comparable antinociceptive and diuretic effects in both sexes. By contrast, SNC80 did not significantly affect the course of CHS in either sex, but females were significantly more sensitive to its locomotor stimulatory effects. Conclusions These results demonstrate that females are more sensitive than males to the CHS-altering effects of spiradoline and that sex differences in the magnitude and direction of opioid-induced sex differences are outcome dependent.     

Acute toxic effects of 3,3′-iminodipropionitrile on hypothalamic-pituitary-gonadal axis in male rats

Exposure to 3,3′-iminodipropionitrile (IDPN) causes persistent neurotoxicity, while its reproductive toxicity in female rats is transient, indicating that gonadotropin-releasing hormone (GnRH) neurons and gonadotrophs receive little or no damage from IDPN and that the transient gonadal toxicity may be also observed in males. To clarify these points, the acute toxic effects of IDPN on hypothalamic-pituitary-gonadal axis of male rats were examined histologically, biochemically and serologically. A single intraperitoneal injection of IDPN (1000 mg/kg body weight) induced signs of neurotoxicity within a day; nevertheless, GnRH neurons were not affected throughout the experimental period. Four days after IDPN treatment, the plasma level of testosterone but not gonadotropins decreased and active caspase 3-immunopositive spermatids increased; both parameters returned to normal levels afterwards. Data from our studies revealed that while IDPN had little or no toxic effect on GnRH neurons or gonadotrophs it was transiently toxic to gonads in both sexes.     

The effects of CRF and α-helical CRF on anxiety in normal and hypophysectomized rats

The effect of corticotrophin-releasing factor (CRF) on anxiety in normal and hypophysectomized (HYPOX) rats was investigated. Intracerebroventricular injection (i.c.v.) of 2 μg of CRF increased anxiety in the elevated plus maze test in normal and HYPOX rats. Anxiety was measured as the ratio of time spent in the open arms of the maze to total time spent in all arms of the maze. CRF also reduced head dipping and rearing in the hole board, and the number of entries into the arms of the plus maze. These latter changes in behavior were independent of the changes in anxiety. All behavioral effects of CRF in HYPOX rats were blocked completely by the CRF receptor blocker, α-helical CRF (50 μg). Completeness of hypophysectomy was assessed by measuring plasma corticosterone (CORT) level changes 20 min after i.c.v. CRF (2 μg). CORT levels of all HYPOX rats given CRF were well below (< 1/10th) resting baseline levels of normal rats. Moreover, i.c.v. injection of saline vehicle nearly tripled CORT levels over resting baseline in normal rats, and CRF increased CORT levels 2-fold over vehicle. Taken together, these findings replicate the observation that CRF administered i.c.v. to rats is selectively anxiogenic in the elevated plus maze. They also indicate that the anxiety produced by CRF does not involve activation of the pituitary-adrenal axis. Rather, CRF-induced anxiety depends on the binding of CRF to central nervous system CRF receptors. Finally, the plasma CORT data indicate that i.c.v. injection of saline vehicle is stressful, as is injection of CRF.     

The effects of morphine and Δ-9-tetrahydrocannabinol on motor activity in rats

Acute treatment of rats either by high doses of morphine or ⁹-tetrahydrocannabinol (THC) decreased locomotor activity. Naloxone reversed morphine-induced depression completely and reversed THC-induced depression only partially. On day 3 of treatment, tolerance developed to the locomotor inhibitory action of THC or morphine and partial cross-tolerance was observed to the depressant action of THC. Naloxone slightly depressed locomotor activity in THC-tolerant rats, but increased motor activity in morphine-tolerant rats.     

The effects of glyburide and insulin on the decreased β-adrenergic responsiveness of the gastrointestinal tract in rats with non-insulin-dependent diabetes

• 1.1. Decreased β-adrenergic responses have been reported in gastro-intestinal tract of rats with diabetes mellitus. Effects of glyburide and insulin on the decreased β-adrenergic responsiveness of the gastro-intestinal tract due to non-insulin-dependent diabetes were investigated using duodenum, jejunum and ileum from rats which were injected with alloxan in their neonatal periods.
• 2.2. Insulin treatment of non-insulin-dependent diabetic rats for 10 days corrected the decreased β-adrenergic responses of the isolated duodenum, jejunum and ileum confirming the previous results obtained from insulin-dependent diabetic rats.
• 3.3. Glyburide treatment alone for 3 weeks also reversed the changes in the gastro-intestinal β-adrenergic responses of non-insulin-dependent diabetic rats. Combination of glyburide with insulin, however, did not cause an additive or supra-additive interaction in terms of β-adrenergic sensitivities of the diabetic tissues.
• 4.4. The results obtained in the present study strongly suggested that non-insulin-dependent diabetes may cause a decrease in the number of gastro-intestinal β-adrenoceptors, while glyburide and insulin treatments correct the changes related to β-adrenoceptors. The effect of insulin on the β-adrenergic sensitivity of diabetic rat duodenum, jejunum and ileum may occur via a direct mechanism, whereas glyburide seems to be effective on the β-adrenergic responses through the increases in the insulin secretion and/or in the number of gastro-intestinal insulin receptors.

     

Behavioural effects of selective μ-, κ-, and δ-opioid agonists in neonatal rats

The behavioural effects of selective -, - and -opioid agonists in 5-, 10- and 20-day-old rats were investigated by observational analysis. The predominant response to -agonists was behavioural depression. High doses (10 mg/kg IP) of morphine and DAGO (d-Ala², NMe-Phe⁴, Glyol⁵-enkephalin) produced overt sedation in all the age groups and also induced catalepsy which was particularly apparent in the 5- and 10-day-old animals. These compounds did not produce any signs of behavioural activation in the neonatal rats. In contrast, rat pups treated with the -agonists U50,488H and PD 117,302 (1,10 mg/kg IP) exhibited marked hyperactivity with increases in wall-climbing and locomotion. Sedative effects of the highest dose of the -agonists began to emerge, however, as the animals grew older, resulting in significant decreases in behaviours such as gnawing and grooming at 20 days of age. The -agonist (+)-tifluadom (0.1–10 mg/kg), but not its corresponding (-)-isomer, produced an increase in activity in 5-day-old rats, thus extending the observations made with U50,488H and PD 117,302 and establishing the stereoselective nature of the response. The involvement of -receptors in opioid-induced hyperactivity was further substantiated by using a variety of opioid antagonists. In this context, the increase in activity induced by U50,488H (10 mg/kg) in 5-day-old neonates was attenuated by naltrexone (1 mg/kg IP) but not by larger doses (10 mg/kg) of either M8008 (which has low affinity for -receptors) or the selective -receptor antagonist ICI 174,864. Finally, DPDPE (d-Pen², d-Pen⁵-enkephalin) which acts selectively at -opioid receptors, did not exert any behavioural effects in either the 5-, 10- or 20-day-old rat pups at doses of up to 10 mg/kg. These results demonstrate behavioural effects of - and -but not -agonists in neonatal rats. There is a clear differentiation between - and -receptor effects and both - and -mediated behaviours show dissimilarities from the adult profile.     

The effects of d-amphetamine, chlordiazepoxide, α-flupenthixol and behavioural manipulations on choice of signalled and unsignalled delayed reinforcement in rats

RATIONALE: Inability to tolerate delays to reward is an important component of impulsive behaviour, and has been suggested to reflect dysfunction of dopamine systems. OBJECTIVES: The present experiments examined the effects of signalling a delayed, large reward on rats' ability to choose it over a small, immediate reward, and on the response to amphetamine, a dopamine receptor antagonist, and a benzodiazepine. METHODS: Three groups of Lister hooded rats were tested on a two-lever discrete-trial delayed reinforcement task in which they chose one pellet delivered immediately or four pellets delivered after a delay. This delay increased from 0 to 60 s during each session. Trials began with illumination of a houselight: in the Houselight group, this remained on during the delay and feeding period. In the No Cue group, the houselight was extinguished at the moment of choice. In the Cue group, a stimulus light was illuminated during the delay. Once trained, the rats were challenged with d-amphetamine (0.3, 1.0, 1.6 mg/kg), chlordiazepoxide (1.0, 3.2, 5.6, 10 mg/kg), alpha-flupenthixol (0.125, 0.25, 0.5 mg/kg), and various behavioural manipulations. RESULTS: Subjects' choice became and remained sensitive to the delay; the cue speeded learning. Amphetamine decreased choice of the large reinforcer in the No Cue group and increased it in the Cue group. alpha-Flupenthixol and chlordiazepoxide generally decreased preference for the delayed reinforcer; flupenthixol reduced the cue's effects, but chlordiazepoxide did not interact with the cue condition. CONCLUSIONS: Signals present during a delay can enhance the ability of amphetamine to promote choice of delayed rewards.     

Influence of prenatal undernutrition on the effects of clozapine and aripiprazole in the adult male rats: relevance to a neurodevelopmental origin of schizophrenia?

Epidemiological and experimental data indicate that maternal undernutrition may sensitize the offspring to the apparition of chronic diseases such as metabolic syndrome and schizophrenia, suggesting that these pathologies may have a developmental origin. To test this hypothesis, we have compared the effects of a 4 weeks treatment of clozapine (30 mg/kg once daily, p.o.) or aripiprazole (10 mg/kg once daily, p.o.) on metabolic and hormonal parameters in 4-month-old male animals from control or 70% prenatally food-restricted mothers (FR30 model). Both neuroleptics did not markedly modify body weight gain and food intake in both controls and FR30 rats. Clozapine decreased insulin secretion in both groups but significantly diminished leptin, corticosterone and glucose plasma levels only in FR30 animals. Aripiprazole decreased corticosterone plasma levels only in FR30 animals. Using quantitative RT-PCR array containing 84 obesity-related genes, we identified several genes involved in energy metabolism regulation whose expression was modified by clozapine or aripiprazole in adult male rat hypothalami. In addition, we demonstrated that expression of some of these genes was differentially affected by each neuroleptic in the hypothalamus of both FR30 and control animals. Although no marked metabolic alterations were observed in both control and FR30 animals after clozapine or aripiprazole treatment, our data indicate that offspring from undernourished mothers exhibit a modified sensitivity to atypical neuroleptics. Our results do not rule out a putative developmental origin of schizophrenia and may help to understand the way by which atypical neuroleptics, such as clozapine, sensitize schizophrenic patients to the development of metabolic disorders.     

Self-administration of methohexital,midazolam and ethanol: effects on the pituitary–adrenal axis in rhesus monkeys

Rationale There is disagreement in the literature with respect to how drugs of abuse affect the functioning of the hypothalamic–pituitary–adrenal (HPA) axis, and whether these changes in endocrine function may be related to the rewarding effects of these drugs.Objectives To determine whether reinforcing drugs with different mechanisms of action affect HPA axis function at doses at which they serve as reinforcers.Methods Seven monkeys (6 male) were randomly assigned to self-administer methohexital—a barbiturate (n=4), midazolam—a benzodiazepine (n=3), or ethanol (n=5). Each monkey had a surgically implanted indwelling venous catheter, and was trained to respond on a fixed ratio of 30 lever presses to receive an injection of drug or saline. Blood samples were obtained before, during, and after the self-administration sessions for the measurement of ACTH and cortisol by radioimmunoassay.Results Although methohexital, midazolam, and ethanol all maintained self-administration behavior across a range of doses, they differed in their effects on ACTH and cortisol. Ethanol inhibited ACTH and cortisol secretion. Methohexital and midazolam both tended to decrease ACTH and cortisol at large doses, and increase these hormones at small doses, but the HPA effects of neither drug differed significantly from when saline was available.Conclusions The neutral overall effect of methohexital and midazolam on HPA activity is consistent with other monkey and human studies, whereas the inhibitory effect of self-administered ethanol in the monkey contrasts with both the rat and human literature. The data in this study suggest that a change in HPA axis activity is not a requirement for drug-reinforced behavior in monkeys.Results from this paper were first presented at the annual meeting of ISPNE, Quebec City, Canada, in August 2001.     

Modulatory effects of morin on hyperglycemia by attenuating the hepatic key enzymes of carbohydrate metabolism and β-cell function in streptozotocin-induced diabetic rats

The present study was aimed to evaluate the effect of morin on blood glucose, insulin level, hepatic glucose regulating enzyme activities and glycogen level in experimental diabetes. Diabetes mellitus was induced by a single intraperitoneal injection of streptozotocin (STZ) (50 mg/kg b.w.). Five days after STZ injection, diabetic rats received morin (25 and 50 mg/kg b.w.) orally for 30 days. Glibenclamide was used as reference drug. Morin treatment significantly reduced the blood glucose and improved the serum insulin levels. Further, a dose-dependent reduction in glucose-6-phosphatase and fructose-1,6-bisphosphatase was observed along with the increase in liver hexokinase and glucose-6-phosphate dehydrogenase activities. Morin supplement were found to be effective in preserving the normal histological appearance of pancreatic islets as well as to preserve insulin-positive β-cells in STZ-rats. Therefore, these findings suggest that morin displays beneficial effects in the treatment of diabetes, mediated through the regulation of carbohydrate metabolic enzyme activities.     

Involvement of δ-opioid receptors in the effects of morphine on locomotor activity and the mesolimbic dopaminergic system in mice

Naltrindole (NTI) and naltriben (NTB), a benzofuran derivative of NTI, were recently synthesized as highly selective -opioid receptor antagonists. Both NTI and NTB failed to suppress the antinociceptive effect induced by morphine. In contrast, both NTI and NTB significantly suppressed the morphine-induced hyperlocomotion and increase in turnover of dopamine (DA) in the mouse limbic forebrain. These results suggest that -opioid receptors play, at least in part, a role in the morphine-induced hyperlocomotion and excitation of mesolimbic DA systems, but not antinociception.     

The study of protective effects and mechanisms of rofecoxib on focal cerebral ischemia- reperfusion injury in rats

AIM : To study the protective effects and the mechanisms of rofecoxib as a specific type 2 cyclooxygenase (COX- 2 inhibitor on focal cerebral ischemia reperfusion injury ( CIRI in rats. METHODS : The model of focal CIRI was induced by reversible middle cerebral artery occlusion ( MCAO with inserting a thread through internal carotid artery, 2 h occlusion followed     

Chronic administration of ethanol on pituitary and hypothalamic β-endorphin in rats and golden hamsters

The effect of chronic exposure to ethanol on hypothalamic and pituitary endorphin levels of rats and golden hamsters was studied. In rats, chronic ethanol consumption caused a decrease in the level of immuno-reactive (i.r.) β-endorphin (β-EP) in the pituitary but an increase of i.r. β-EP in the hypothalamus. The Met-enkephalin level in the hypothalamus of ethanol-treated rats remained the same as the control. The body weights, as well as food and liquid intake, of ethanol-treated rats were observed to be lower than the controls. In golden hamsters, i.r. β-EP level in the hypothalamus and pituitary remained unchanged with chronic ethanol consumption. The body weight and liquid intake of golden hamsters also remained the same as the controls. Since the changes of pituitary and hypothalamic β-EP after ethanol administration were found only in rats but not in golden hamsters, it is likely that the effects of ethanol observed in rats are not specific.     

The effects of adenosine-5′-ethylcarboxamide on liver blood flow and hepatic glucose,lactate and pyruvate balances in dogs

Summary The actions of adenosine-5-ethylcarboxamide (744–96), a long-acting adenosine analoge, on liver, portal and intestinal balances of glucose, lactate and pyruvate and on hepatic and portal blood flow were investigated in 6 chloralose-anaesthetized mongrel dogs. 744–96 led to an increase in portal and hepatic blood flow. Glucose release by the liver and glucose uptake by the non-hepatic splanchnic area (portal balance) were markedly increased by 744–96. Hepatic lactate and pyruvate balances were reversed from uptake to release by the adenosine analogue. The changes in glucose balances compare closely to the actions of glucagon, which is known to be released by 744–96. Apart from these possible glucagon-mediated actions, a direct action of the adenosine analogue must be assumed from the changes in lactate metabolism. The results of this study are indicative of a substratemobilising action of adenosine in addition to its wellknown vasodilatory action.