Interactions of carbon tetrachloride and promethazine in the rat—I: Effects of promethazine on the concentrations of carbon tetrachloride in blood and liver,and on the production of chloroform

The effects of Promethazine (PM, 78 μmoles/kg body wt, i.p.) on the concentrations of CCl₄ in samples of blood and liver of male, fasted rats after oral dosing with CCl₄ have been determined. With an administered dose of CCl₄ of 13 moles/kg body wt the concentrations of CCl₄ in the blood and liver were measured using gas chromatography with a flame ionisation detector. It was found that Promethazine delayed absorption of CCl₄ from the gastro-intestinal tract by approximately 2 hr as judged by blood levels of CCl₄; the maximum blood concentration (C_max) and the total absorption of ccl₄ (assessed by the area under the plot of blood concentration vs time during the first 6 hr after administration of CCl₄) were not significantly changed by Promethazine treatment. Liver and blood measurements were carried out on each rat in this series and the ratio of the CCl₄-concentrations in liver: blood were found to lie within the range 8–12 when studied in the absence of Promethazine treatment.Gas chromatography with electron capture was used on serial samples of blood from the same rat to measure CCl₄ and CHCl₃ concentrations following oral administration of 13, 6.5 or 1.3 mmoles CCl₄/kg body wt. The increase in blood CCl₄ levels at all doses of CCl₄ administered was delayed by about 2 hr by administration of Promethazine. The maximum blood concentrations of CCl₄ and total amount absorbed (judged by area under the plot of blood concentration vs time) were dose-related to the amount of CCl₄ administered with or without Promethazine administration. Blood concentrations of CHCl₃ were relatively constant over the range of CCl₄-doses used indicating that the metabolic production rate of CHCl₃ is saturated at rather low doses of CCl₄ administered.     

Effect of hypophysectomy on the stimulation of liver growth by α-hexachlorocyclohexane,phenobarbital, and partial hepatectomy in the rat

Summary -Hexachlorocyclohexane (-HCH) or phenobarbital (PB) elicit growth and cell multiplication in rat liver.In hypophysectomized rats, -HCH and PB induce an increase in liver mass, but no increase in liver DNA. Hypophysectomy without additional treatment results in a decrease of liver size and RNA, while the DNA content remains unchanged, thereby leading to a relative DNA surplus. 1/3-hepatectomy in hypophysectomized animals leads to a small increase of hepatic DNA only; after 2/3-hepatectomy 75–80% of the original liver DNA are restored. In rats with intact hypophysis losses of liver DNA are known to be restored completely.The findings suggest that the relative DNA surplus in hypophysectomized rats prevents the stimulation of DNA synthesis by weak growth stimuli such as -HCH, PB, and 1/3-hepatectomy. If the relative DNA surplus is eliminated by partial hepatectomy, the inducers do produce DNA multiplication. It is concluded that the induction of liver growth and cell multiplication by -HCH and PB does not require the presence of the hypophysis or one of its hormones.Abbreviations HCH 1,2,3,4,5,6-hexachlorocyclohexane=benzene hexachloride - PB phenobarbital - b.w. body weight - BHT butylhydroxytoluene - STH somatotrophic hormone - ACTH adrenocorticotrophic hormone     

Effect of β-N-methylamino-l-alanine on oxidative stress of liver and kidney in rat

β-N-methylamino-l-alanine (l-BMAA) is a neurotoxic amino acid, found in the majority of cyanbacterial genera tested. Evidence for implication of l-BMAA in neurodegenerative disorders, like amyotrophic lateral sclerosis (ALS), relies on bioaccumulation and biomagnification from symbiotic cyanobacteria. The involvement of l-BMAA in oxidative stress was demonstrated in several studies in the central nervous system. In the present study, we investigated the effect of l-BMAA on the oxidative stress responses of liver and kidney in rats treated by intraperitoneal administration with this amino acid. Oxidative stress was demonstrated by the quantification of lipid peroxidation, the measurement of both catalase and glutathione peroxidase activities, as well as the quantification of glutathione (GSH) levels and the total antioxidant capacity. It was observed that l-BMAA caused a significant increase in the degree of lipid peroxidation and catalase activity in both organs. A significant increase in glutathione peroxidase activity was obtained only in liver, whereas glutathione levels were also increased in both organs. The total antioxidant capacity decreased in liver and increased in kidney. These results suggest that the oxidative stress was higher in liver than in kidney, and might be crucial for l-BMAA toxicological action.     

Dietary α-tocopherol prevents dehydroepiandrosterone-induced lipid peroxidation in rat liver microsomes and mitochondria

Dehydroepiandrosterone (DHEA), an adrenal steroid, causes lipid peroxidation in rat liver microsomes and mitochondria and induces hepatocarcinogenesis. It was investigated whether α-tocopherol, a naturally occurring free radical chain terminator, could decrease lipid peroxidation. When DHEA-free diet supplemented with increasing concentrations of α-tocopherol (25, 50, 100, 200, 400 and 1000 mg/kg diet) was fed to rats for 7 days, a marked lipid peroxidation (measured as thiobarbituric acid reactive substances formation) was observed at concentrations 25 and 50 mg/kg in liver microsomes and mitochondria isolated from these animals. Lipid peroxidation was significantly reduced at concentrations ≥ 100 mg/kg. When DHEA (500 mg/kg diet) was fed to rats simultaneously with increasing concentrations of α-tocopherol, strong lipid peroxidation was observed at a-tocopherol concentrations ≤ 200 mg/kg diet. However, microsomes and mitochondria isolated from livers of rats fed a-tocopherol at doses of 400 and 1000 mg/kg diet produced only negligible amounts of thiobarbituric acid reactive substances. The data show that high concentrations of α-tocopherol in the diet decrease DHEA-induced microsomal and mitochondrial lipid peroxidation. Our results support the concept thatα-tocopherol can protect against DHEA-induced lipid peroxidation and consequently against steroid-induced liver cell damage and, perhaps, also tumour development.     

Hepatoprotective effects of diethylcarbamazine in acute liver damage induced by carbon tetrachloride in rats

This research was carried out to determine a potential role of leukotrienes in the acute hepatotoxicity induced by CC14 in rats. An inhibitor of leukotrienes biosynthesis, diethylcarbamazine (DEC, 25 and 50 mg ·kg-1 ip) exerted hepatoprotective effects, decreasing the activity of alanine aminotransfer-ase in serum and the concentration of liver triglycerides. DEC reduced histological damage of liver evidenced by electron microscopy. The hepatoprotective effects of DEC were dose-dependent. The results favor the role of leukotrienes in CC14 hepatotoxicity.     

Effect of haloperidol on reflex activation of rat α-motoneurones

Summary Effects of haloperidol on rat flexor and extensor -motoneurones were studied in ventral roots of laminectomized rats under halothane anesthesia. The -motoneurones were activated by tetanic stimulation of low-threshold afferents (group I and II), either of the ipsilateral peroneal nerve (flexor -motoneurones) or gastrocnemius-soleus nerve (extensor -motoneurones).Haloperidol, given in the doses of 0.075, 0.15 and 0.30 mg/kg i.p. inhibited the reflex activation of flexor -motoneurones; higher doses seemed to be more effective than lower ones. Apomorphine (2 mg/kg s.c.) partially antagonized the inhibitory action of haloperidol with some latency. Higher doses of haloperidol (0.15–0.60 mg/kg i.p.) also inhibited the reflex activation of extensor -motoneurones; this inhibitory effect was, at least for a short time, antagonized by apomorphine (2 mg/kg s.c.).The threshold for reflex activation both of flexor and extensor -motoneurones was raised by haloperidol and lowered by a subsequent administration of apomorphine.Our results suggest that akinesia and catalepsy, induced in rats by haloperidol might be, at least in part, due to a decrease in sensitivity of -motoneurones to proprioceptive stimuli.     

Effect of Stryphnodendron adstringens (barbatimão) on energy metabolism in the rat liver

The action of a barbatim?o extract on hepatic energy metabolism was investigated using isolated mitochondria and the perfused rat liver. In mitochondria the barbatim?o extract inhibited respiration in the presence of ADP and succinate. Stimulation occurred, however, after ADP phosphorylation (state IV respiration). The ADP/O and respiratory control ratios were reduced. The activities of succinate-oxidase, NADH-oxidase and the oxidation of ascorbate were inhibited. The ATPase of intact mitochondria was stimulated, but the ATPases of uncoupled and disrupted mitochondria were inhibited. In perfused livers the extract caused stimulation of oxygen consumption, inhibition of gluconeogenesis and stimulation of glycolysis. Glucose release due to glycogenolysis was stimulated shortly after the introduction of the extract, but inhibition gradually developed as the infusion was continued. Apparently the barbatim?o extract impairs the hepatic energy metabolism by three mechanisms: (1) uncoupling of oxidative phosphorylation, (2) inhibition of mitochondrial electron transport, and (3) inhibition of ATP-synthase.     

α-Tocopheryl hemisuccinate administration increases rat liver subcellular α-tocopherol levels and protects against carbon tetrachloride-induced hepatotoxicity

Rats were administered a series of tocopherol analogs 18 h prior to a hepatotoxic dose of carbon tetrachloride (CCl₄). Of the compounds tested, only d-α-tocopheryl hemisuccinate (TS) provided significant protection against CCl₄-induced hepatotoxicity. No protection was observed with either d-α-tocopherol (α-T) or a tocopherol succinate ether derivative, d-α-tocopheryloxybutyric acid (TSE). None of the tocopherol analogs significantly inhibited CYP2E1 activity as measured by oxidation of p-nitrophenol. Liver homogenates and subcellular fractions (cytosol, nuclei, plasma membranes, mitochondria and microsomes) were collected 18 h after tocopherol analog administration in the absence of CCl₄. Homogenate and subcellular α-T levels were not significantly increased following TSE administration but were increased 2–3 fold following TS and α-T administration. Total tocopherol levels (α-T+TS+TSE) in liver homogenates and subcellular fractions were highest in rats supplemented with TS. In these animals, TS was detected in all subcellular fractions and total tocopherol levels were increased from 6–23 fold over those seen in controls and 2–9 fold over α-T treated rats. In vitro studies in which liver homogenates and subcellular fractions were peroxidized with ascorbate and ADP/Fe suggest that increasing levels of α-T but not TS correlates with increased protection against lipid peroxidation. These results suggest that the ability of TS to protect against CCl₄-induced hepatotoxicity relates to its enhanced hepatic accumulation and subsequent hydrolysis to α-T.     

Effect of endothelium on basal and α-adrenoceptor stimulated calcium fluxes in rat aorta

Summary The rate of unstimulated influx of Ca²⁺ into rat aorta smooth muscle, measured as uptake of ⁴⁵Ca, was inhibited in the presence of endothelium as compared to influx in the absence of endothelium. Efflux of ⁴⁵Ca from unstimulated prelabelled tissues was also reduced in the presence of endothelium. In normal physiological solution the rate of influx and efflux of Ca²⁺ stimulated by B-HT 920 (1 and 10 M), but not that stimulated by phenylephrine (30 nM and 1 M), was also reduced in the presence of endothelium. In the presence of the calcium entry blocker flunarizine (3 M), phenylephrine (1 M) stimulated efflux of Ca²⁺ was inhibited by the presence of endothelium. A correlation between inhibition of Ca²⁺ influx and modulation of -adrenoceptor agonist-induced contractions by endothelium could not be demonstrated, and methylene blue, an antagonist of endothelium mediated inhibition of B-HT 920 contractions, did not affect Ca²⁺ influx stimulated by the agonist. The effects of endothelium on Ca²⁺ influx and efflux are unlikely to be due to alterations by endothelium of diffusion of ⁴⁵Ca or the agonists in the vessel. The results demonstrate that an endothelial derived factor or factors can reduce calcium influx into smooth muscle cells and also modulate the release of calcium from cells, perhaps by affecting intracellular calcium pumping mechanisms. A reduction of calcium influx cannot be the sole explanation for the modulatory effect of endothelium on -adrenoceptor agonist-induced contractions but an effect on intracellular calcium metabolism may be important.     

Dibromoethane effects on the induction of γ-glutamyl-transpeptidase positive foci in rat liver

The initiating and promoting activities of 1,2-dibromoethane in rat liver were investigated using the enzyme-altered foci bioassay. The incidence of -glutamyl-transpeptidase (GGT)-positive foci was used as an early histochemical marker for hepatocarcinogenesis. To determine the initiating activity of 1,2-dibromoethane, the halogenated hydrocarbon was administered orally in corn oil as single or multiple doses (60 or 120 mg/kg) either before or after partial hepatectomy. The animals were then given a promoting regimen of 500 ppm phenobarbital in their drinking water. No increase in the incidence of GGT-positive foci was observed in any of the 1,2-dibromoethane initiation groups. The tumor promoting activity of 1,2-dibromoethane was determined in partially hepatectomized rats which were initiated with N-nitrosodiethylamine (30 mg/kg; po), and one week later were administered 1,2-dibromoethane (10 or 30 mg/kg) orally in corn oil five times weekly for 8 weeks. Control groups receiving sham hepatectomy or no initiator were also treated with the halogenated hydrocarbon five times weekly. Only in those animals which received partial hepatectomy, N-nitrosodiethylamine initiation, and 1,2-dibromoethane was the incidence of GGT-positive foci significantly increased. These results do not support significant initiator activity of 1,2-dibromoethane in rat liver, but do indicate that 1,2-dibromoethane possesses promoter activity which may contribute to its carcinogenic activity.     

Effect of phenytoin sodium on macrophages in rat wounds

本实验旨在研究苯妥英钠（ＰＳ）对伤口巨噬细胞（Ｍ）的影响．从置入大鼠背部伤口的聚乙烯醇海绵中收集巨噬细胞，分别测定其吞噬功能，肿瘤坏死因子α（ＴＮＦα）和白介素１（ＩＬ－１）的释放以及对成纤维细胞增殖调节作用，通过牵拉伤口组织致其断裂时溢出的水的重量而测定伤口牵张强度．结果表明，伤口Ｍ的功能在伤后ｄ５达到高峰，ＰＳ１，１０，５０ｇ·Ｌ－１浓度依赖性地增加伤后ｄ５的伤口Ｍ的数量，吞噬功能，ＴＮＦα和ＩＬ－１的释放，增强Ｍ对成纤维细胞增殖的刺激作用，增强伤口牵张强度．结果说明ＰＳ加速伤口愈合，与其增强Ｍ的功能有关．     

Investigation of in vivo toxicity of hydroxylamine sulfate and the efficiency of intoxication treatment by α-tocopherol acetate and methylene blue

ObjectivesInvestigation of hydroxylamine sulfate toxicity mechanism in vivo and estimation of α-tocopherol acetate and methylene blue efficiency in poisoning treatments.MethodsIn vivo experiments were conducted on 102 Wistar Han rats. The experiments investigated the hematotoxic and oxidative stress effects of hydroxylamine sulfate in acute and subacute toxicity treatment of animals. Electron Spin Resonance was used for quantitative determination of blood and liver tissue parameters alterations after intoxication. The osmotic fragility of erythrocytes, lipid peroxidation intensity and level of SH-groups in liver of rats were determined by established biochemical assays.ResultsHydroxylamine sulfate cause an acute hematotoxicity and oxidative stress in vivo as demonstrated by the appearance of free oxidized iron in blood, reduced glutathione content and increased lipid peroxidation in liver. The experimental studies showed the formation of Hb–NO, MetHb in erythrocytes and as well of stable complex of reduced iron (Fe²⁺) with hydroxylamine sulfate. Methylene blue treatment does not reduce the Hb–NO or MetHb levels in intoxicated animals while administration of α-tocopherol acetate reduces substantially lipid peroxidation.ConclusionsOxidative stress is a key mechanism of acute hematotoxicity caused by hydroxylamine sulfate. Methylene blue is not suitable antidote in case of hydroxylamine intoxication.     

Effect of removing the endothelial cells on the reactivity of rat aortic segments to different α-adrenoceptor agonists

Summary The influence of removing the endothelial cells on the -receptor-mediated contractile response in segments of rat aorta was investigated using agonists with a range of affinity for ₁ and ₂. The preferential ₁ were methoxamine, cirazoline, ST 587, and Sgd 101/75 and the preferential ₂ were B-HT 920, clonidine, and guanfacine. When the endothelium was intact, the intrinsic activity (compared to noradrenaline) varied widely (0.0–0.7) for both groups of agonists. After removal of the endothelium the intrinsic activity was increased in each case to that of noradrenaline, or close to it. Furthermore, an increase in potency was obtained for each agonist, although to different degrees. No correlation, however, was found between the selectivity of the agonists and the degree of enhancement caused by the removal of the endothelium, in terms of either the intrinsic activity or the potency. Moreover, the use of the selective ₂ antagonist rauwolscine on intact tissues did not mimic the effect of removing the endothelium. Therefore, the -receptors of the endothelium could not be classified as either of the ₁ or ₂.This study was supported by a grant of the Deutsche Forschungsgemeinschaft.     

Effect of α2-adrenoceptor agonists on the expression of morphine-withdrawal in rats

Summary Previous studies using clonidine indicate that ₂-adrenoceptors are involved in suppressing opiate-withdrawal symptoms. However, clonidine may act as a partial agonist at ₂-adrenoceptors and it also possesses significant ₁-receptor agonist activity.The aim of this study was to determine the role of ₂-adrenoceptors in the expression of opiate withdrawal signs using morphine-dependent rats. A range of agonists were selected for study on the basis of their differential preferences for -adrenoceptors.Hooded Wistar rats were made physically dependent on morphine (s.c. injection of an emulsion releasing a total of 250 mg/kg of morphine base over 48 h). Test drugs were injected s.c. followed by naloxone (10 mg/kg i.p.) 20 min later. The incidence of 5 selected withdrawal signs was recorded during the following 20 min. The ₂-adrenoceptor agonists displayed different profiles of activity. Azepexole (1–10 mg/kg) reduced all signs. Clonidine (80–800 g/kg) reduced all signs except paw shakes while guanfacine (25–250 g/kg) reduced all except jumping and diarrhoea. Talipexole (0.1–1 mg/kg) reduced all signs except diarrhoea which was not affected and jumping which was markedly enhanced. UK 14,304 (80–800 g/kg) reduced jumps, potentiated paw shakes but did not affect body shakes, teeth chattering or diarrhoea. The results suggest that there are subpopulations of ₂-adrenoceptors that modulate the expression of opiate withdrawal signs and/or that some of the drugs used affect receptors other than ₂-adrenoceptors.     

Studies on comparative efficacy of α-linolenic acid and α-eleostearic acid on prevention of organic mercury-induced oxidative stress in kidney and liver of rat

The present study was undertaken to evaluate the effect of α-linolenic acid and α-eleostearic acid, two isomers of linolenic acid, against oxidative stress induced by organic mercury in kidney and liver cells of rat. Male albino rats were divided into six groups. Groups 1, 2 were normal control and methyl mercury chloride (MeHgCl) treated (5 mg/kg BW/day) control, respectively. Groups 3, 4, 5 and 6 were orally treated with different doses of two fatty acids (0.5% and 1.0% of total lipid given for each isomer) along with MeHgCl (5 mg/kg BW). Results showed that activity of antioxidant enzymes viz. catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), reduced glutathione (GSH) in liver and kidney decreased significantly due to oxidative stress generated by MeHg. Administration of the linolenic acid isomers almost restored all the altered parameters and also reduced lipid peroxidation and leakage of trans-aminase enzymes from liver to blood due to liver injury when administrated in higher doses. Histopathology of liver and kidney cells showed that administration of α-linolenic acid significantly reduced the damage generated by MeHg. Thus, α-linolenic acid and α-eleostearic acid could serve as cost-effective and natural phytochemical preparation to protect against the adverse effects caused by organic mercury in human.     

Effect of tetrandrine on proto-oncogene c-fos expression in rat cerebrum

目的：本研究旨在探讨Ｔｅｔ对林丹—一种通过细胞内游离钙（［Ｃａ２＋］ｉ）介导大脑ｃｆｏｓ基因表达的神经毒剂—诱导的大鼠大脑ｃｆｏｓ基因表达的影响．方法：Ｎｏｒｔｈｅｒｎ印迹杂交，斑点杂交技术及双波长薄层色谱扫描分析．结果：大鼠口服林丹３０ｍｇ·ｋｇ－１１小时后大脑ｃｆｏｓ基因表达明显增强至１４６ｍｍ２，而在口服林丹前３０ｍｉｎ分别口服Ｔｅｔ１，２及４ｍｇ·ｋｇ－１，大鼠大脑ｃｆｏｓ基因表达被明显抑制（分别为８６，４０和３９ｍｍ２），其抑制程度呈剂量依赖关系．结论：Ｔｅｔ抑制Ｃａ２＋激动剂类神经毒剂—林丹诱导的大鼠大脑ｃｆｏｓ基因转录水平的表达．     

Effect of The effects of Δ 9-tetrahydrocannabinol on the metabolism of norepinephrine in rat brain on the morphine-induced hyperactivity of mice

The effect of ⁹-tetrahydrocannabinol (THC) on the locomotor activity-stimulating action of morphine has been investigated in mice. THC (10 mg/kg) has been found to potentiate morphineinduced hyperactivity. On the other hand, the stimulating action of morphine on motor activity strongly diminished in mice rendered tolerant by the implantation of a morphine pellet. The pretreatment of morphine-tolerant mice with the same dose of THC did not change the effect of morphine on the motor activity. These results suggest that tolerance also developed to the potentiating action of THC on morphine-induced hyperactivity during the development of tolerance to this action of morphine.     

Effect of Hemidesmus indicus on ischemia–reperfusion injury in the isolated rat heart

The root extract of Hemidesmus indicus (Linn.) R. Br. (Asclepiadaceae) (HI) was studied for its cardioprotective effect in Langendorff-perfused rat hearts. HI was perfused for 15?min at a concentration of 0.09?g/L prior to 30?min global ischemia/120?min reperfusion (I/R). Recovery of functional parameters, reperfusion arrhythmias, and infarct size (TTC staining) served as the end-points. After 15?min of perfusion with HI, the left ventricular developed pressure (LVdevP) and HR (heart rate) were not altered significantly (p > 0.05), as compared with the pre-drug values. During R, HI showed a significantly higher (p?<?0.05) recovery of LVdevP at nearly all time points. The recovery of maximal rate of pressure development (+dP/dt_max) and left ventricular end-diastolic pressure (LVEDP) at 40?min of R were significantly better than in non-treated controls. There was also a significant reduction in the total number of ventricular premature beats (VPB) and duration of ventricular tachycardia (VT). HI can protect ischemic myocardium against contractile dysfunction and reperfusion-induced arrhythmias and reduce the extent of irreversible tissue damage following I/R in rat hearts.