The effect of piracetam on lipid peroxidation in the rat brain

The effect of piracetam on lipid peroxidation (LPO) in the rat brain was investigated. Piracetam was shown not to catalyze LPO and not to stimulate production of active forms of oxygen but to increase LPO only in the presence of traces of transition of metal ions. In all probability, the reason of this is the capacity of piracetam to chelate these metals. In this case their catalytic activity with respect to LPO increases. The performed studies demonstrate that the observed increase in LPO in the rat brain during the use of piracetam is an artefact due to the presence of traces of transition metal ions.     

Lipid Association Increases the Potency Against Primary Medulloblastoma Cells and Systemic Exposure of l-(2-Chloroethyl)-3-Cyclohexyl-1-Nitrosourea (CCNU) in Rats

Purpose. To reduce the systemic toxicity and prolong the systemic presence of l-(2-chloroethyl)-3-cyclohexyl-l-nitrosourea (CCNU), a lipid-based drug carrier was designed and characterized. Methods. The degree of CCNU association with lipid vesicles composed of 1,2-dimyristoyl-sn- glycero-3-phosphocholine (DMPC) and l,2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG) (1:1, m/m) was characterized and the drug decomposition rates of lipid-drug complexes were monitored. Effects of lipid association on drug potency against medulloblastoma cells and total systemic drug exposure in rats were determined. Results. At a CCNU:lipid molar ratio greater than 1:5, more than 90% of the drug was associated with the lipid vesicles. In aqueous suspensions, lipid association significantly reduced the first-order drug decomposition rate. In addition, lipid-associated CCNU exhibited a 4-fold increase in drug sensitivity with medulloblastoma cells. IC₅₀ values for CCNU admixed and encapsulated with lipid vesicles were 18 ± 4.9 and 14.0 ± 2.2 M, respectively, compared to 83 ± 11.0 M for free CCNU. When administered to rats, lipid-associated CCNU increased the AUC (area under the concentration-time curve) of CCNU by approximately 2-fold (20.46 ± 2.15 compared to 39.59 ±1.87 gmin/ml), and the terminal half-life (t_1/2) by almost 9-fold (17 ± 9 compared to 147 ± 48 min) over free CCNU. Despite the increase in total systemic drug exposure, rats treated with lipid-associated CCNU exhibited a significantly lower frequency of acute neurotoxicity. Conclusions. These data indicate that CCNU associated with lipid vesicles may increase drug stability, potency, and systemic exposure in rats.     

Inhibitory effect of melatonin on homocysteine-induced lipid peroxidation in rat brain homogenates

Oxidative damage is implicated in several pathologies including cardiovascular disease. As a model system to study the response of cells to oxidative insults, homocysteine toxicity was examined since it is an independent risk factor for atherosclerotic disease. The levels of malondialdehyde and 4-hydroxyalkenals were assayed as an index of oxidatively damaged lipid. In in vitro experiments, the increase of lipid peroxidation products induced by homocysteine were concentration- and time-dependent. To study the protective effect of melatonin on homocystine induced lipid peroxidation, brain homogenates were treated with different concentrations of melatonin. The accumulation of malondialdehyde and 4-hydroxyalkenals induced by homocysteine was significantly reduced by melatonin in a concentration-dependent manner. Additionally, a melatonin concentration of 1.5 mM reduced the levels of oxidatively damaged lipid products below those measured in control homogenates (no homocysteine, no melatonin). These data suggest that melatonin, an endogenous antioxidant may have a role in protecting cells from oxidative damage due to homocysteine and they support the idea that pharmacological concentrations could be used as a therapeutic agent in reducing cardiovascular disease where homocysteine may be a causative or contributing agent.     

Reproduction and teratological studies with 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU) in the rat and rabbit.

1-(2-Chloroethyl)-3-Cyclohexyl-1-Nitrosourea (CCNU), one of a group of nitrosoureas used for the treatment of cancer, was evaluated for its effects on various parameters of reproduction and postnatal development in the rat and on embryonal and fetal development in the rat and rabbit. Weekly ip treatment of male rats for 9 weeks with 2.5, 5, or 10 mg/kg/week had no effect on copulatory activity, but untreated females bred to males receiving 5 or 10 mg/kg/week had a significant decrease in numbers of implantations, and the resorption rate was increased at all levels of treatment. Treatment of female rats ip with 0.75, 1.5, or 3.0 mg/kg/day for 14 days prior to breeding and through Day 20 of gestation resulted in a high incidence of intrauterine, perinatal, and postnatal mortality. Doses of 2, 4, or 8 mg/kg/day given ip during different 4-day intervals of organogenesis or 6 mg/kg/day given throughout organogenesis (Days 6–15) were teratogenic in the rat. Major abnormalities such as omphalocele, ectopia cordis, hydrocephalus, syndactyly, anophthalmia, and aortic arch anomalies occurred most frequently in groups given 4 or 8 mg/kg on Days 6–9, or 6 mg/kg on Days 6–15 of gestation. Treatment of female rats ip with doses of 0.75, 1.5, or 3.0 mg/kg/day during the last third of gestation and throughout 21 days of lactation had no effect on prenatal, perinatal, or postnatal survival, but pup weights on Day 21 were reduced at all levels of treatment. Doses of 1.5, 2.25, or 3.0 mg/kg administered iv or ip to rabbits on Days 6–18 of gestation resulted in a high incidence of abortion at 3 mg/kg but no drug-related fetal anomalies were detected.     

The effect of swimming exercise on lipid peroxidation in the rat brain, liver and heart

We intended to study the effect of swimming exercise on the brain, liver and heart malondialdehyde (MDA) levels which are the last product of oxidation, and to compare them with the brain, liver and heart MDA levels of controls. The experiments were carried out on 20 Wistar rats which were fed with a standard laboratory chow diet ad libitum. Rats were distributed in two groups, control group (n = 10) and exercise group (n = 10). The exercise group rats were exposed to swimming exercise for 30 minutes. After this animals in each group were sacrificed by decapitation, their brain, liver and heart tissues were quickly removed. MDA levels of the brain, liver and heart were determined according to the method in which MDA reacts with thiobarbituric acid. Results were evaluated by the Mann-Whitney U test. The liver and heart MDA levels in the exercise group were (29.59+/-6.73 and 10.49+/-1.90 nmol/g tissue, respectively) significantly higher than in the control group (21.78+/-3.46 and 8.86+/-1.25 nmol/g tissue, p<0.01 and p<0.05, respectively). However, the brain MDA levels were similar in both groups (exercise group 19.37+/-5.50 nmol/g tissue and control group 16.58+/-2.44 nmol/g tissue; p=0.325). It is concluded that swimming exercise might cause oxidative stress.     

Stereoselective monooxygenation of carcinostatic 1-(2-chloroethyl)-3-(cyclohexyl)-1-nitrosourea and 1-(2-chloroethyl)-3-(trans-4-methylcyclohexyl)-1-nitrosourea by purified cytochrome P-450 isozymes

Three highly purified forms of liver microsomal cytochrome P-450 (P-450a, P-450b and P-450c) from Aroclor 1254-treated rats catalyzed 1-(2-chloroethyl)-3-(cyclohexyl)-1-nitrosourea (CCNU) and 1-(2-chloroethyl)-3-(trans-4-methylcyclohexyl)-1-nitrosourea (MeCCNU) monooxygenation in the presence of purified NADPH-cytochrome P-450 reductase, NADPH, and lipid. Differences in the regioselectivity of CCNU and MeCCNU monohydroxylation reactions by the cytochrome P-450 isozymes were observed. Cytochrome P-450-dependent monooxygenation of CCNU gave only alicyclic hydroxylation products, but monooxygenation of MeCCNU gave alicyclic hydroxylation products, an αhydroxylation product on the 2-chloroethyl moiety, and a trans-4-hydroxymethyl product. A high degree of stereoselectivity for hydroxylation of CCNU and MeCCNU at the cis-4 position of the cyclohexyl ring was demonstrated. All three cytochrome P-450 isozymes were stereoselective in primarily forming the metabolite cis-4-hydroxy-trans-4-Methyl-CCNU from MeCCNU. The principal metabolite of CCNU which resulted from cytochromes P-450a and P-450b catalysis was cis-4-hydroxy CCNU, whereas the principal metabolites from cytochrome P-450c catalysis were the trans-3-hydroxy and the cis-4-hydroxy isomers. Total amounts of CCNU and MeCCNU hydroxylation with cytochrome P-450b were twice that with hepatic microsomes from Aroclor 1254-treated rats. Catalysis with cytochromes P-450a and P-450c was substantially less effective than that observed with either cytochrome P-450b or hepatic microsomes from Aroclor 1254-treated rats.     

The pharmacokinetics of [3H]1-[1-(2-thienyl)cyclohexyl]piperidine (TCP) in Sprague-Dawley rats

Using adult male Sprague-Dawley rats, we examined the blood protein binding and pharmacokinetics of the potent phencyclidine (PCP) receptor ligand 1-[1-(2-thienyl)cyclohexyl]piperidine (TCP). The average percentage of unbound [3H]TCP in rat serum was 42 +/- 6% and the [3H]TCP blood to plasma ratio was 0.98 +/- 0.03 (mean +/- SD, n = 5 in both studies). For the pharmacokinetic studies, [3H]TCP and 1 mg/kg unlabeled TCP were administered as an iv bolus dose. The average [3H]TCP elimination half-life was 2.1 hr. In contrast, total radioactivity in the plasma had a much longer half-life, suggesting much slower metabolite elimination. The average distribution volumes were 27 +/- 17, 15.6 +/- 6.2, and 5.6 +/- 3.0 liters/kg for V beta, Vss, and Vc, respectively. Total body and renal clearance values were 132 +/- 45 and 1.1 +/- 0.4 ml/min/kg, respectively. When TCP pharmacokinetic parameters were compared to PCP pharmacokinetic data in rats from a previous study, a strikingly similar pharmacokinetic profile was found. These data indicated that TCP and PCP are equivalent, from a pharmacokinetic point of view, and that the higher pharmacological potency of TCP over PCP is probably due to receptor-mediated differences.     

Heme metabolism in liver and spleen of 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU)-treated rats

The effect of 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU), an anticancer alkylating agent of the nitrosourea group, on liver and spleen enzymes involved in the control of heme metabolism was studied. A single oral dose of 50 or 100 mg/kg CCNU caused a time-dependent loss in weight of both spleen and liver. Seven days after CCNU treatment (lOO mg/kg) the weights were at 45 and 65% of controls respectively. The activity of δ-aminolevulinic acid synthetase (ALA-S), the rate-limiting enzyme in heme biosynthesis, declined in spleen and liver to 11 and 24% of control values, respectively, 7 days after CCNU treatment. Heme oxygenase activity, the rate-limiting enzyme of heme breakdown, was moderately increased in liver and spleen following CCNU administration. In liver, heme oxygenase activity was 142% of control values at 24 hr, and in spleen the activity was 180% of controls at 1 week. Pretreatment of the animals with phenobarbital (PB) (40 mg/kg/day, i.p.) for 4 days caused a reversal in the decline of liver weight with no effect on the decline in spleen weight following CCNU treatment. Similarly, PB pretreatment reversed the decline in hepatic ALA-S activity after CCNU administration but had no effect on the decline in splenic ALA-S activity. This study indicates that CCNU causes significant decreases in the activity of enzymes of heme biosynthesis in spleen and liver. The CCNU hemotoxicity in the liver was reversed by PB pretreatment whereas the splenic hemotoxicity was unchanged.     

Enhancement of 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU) toxicity by acetohydroxamic acid analogues of 3-nitropyrazole in vitro

A series of acetohydroxamic acid derivatives of 3-nitropyrazole were synthesized and evaluated for their ability to potentiate (chemosensitization) the activity of 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU) against EMT-6 mouse mammary tumor cells in vitro. The compounds were designed to test the hypothesis that the chemosensitizing activity of the analogues would be proportional to the rate of isocyanate formation via a Lossen rearrangement, in part a function of the leaving group at the N terminus of each acetohydroxamate. Substitution of acetohydroxamic acid side chains at the N-1 position of the parent 3-nitropyrazole resulted in compounds which were preferentially toxic to cells treated under hypoxic conditions, and which were capable of enhancing the toxicity of CCNU in hypoxia. As was observed for cytotoxicity, the enhancement of CCNU toxicity by these sensitizing agents was significantly reduced under aerobic treatment conditions. A strong correlation was established between hypoxic toxicity and chemosensitizing potency. The activity of the analogue, however, was not proportional to their excepted rates of Lossen rearrangement. Nevertheless, several potent chemosensitizing compounds were identified; some of which were 10–50 x 's more potent on a molar basis than Misonidazole, the reference chemosensitizing compound.     

Capillary Gas Chromatography and Thermionic N-P-Specific Detection of 13-Bis(2-chloroethyl)-l-nitrosourea (BCNU) or l-(2-Chloroethyl)-3-cyclohexyl-l-nitrosourea (CCNU) in Stability and Pharmacokinetic Studies

An expedient, rapid, and sensitive capillary gas chromatographic method for the analysis of l,3-bis(2-chloroethyl)-l-nitrosourea (BCNU) or l-(2-chloroethyl)-3-cyclohexyl-l-nitrosourea (CCNU) in plasma is described. Separation of the underivatized nitrosourea compounds was performed on a 0.33-mm-i.d., 25-m fused-silica, SE-30 capillary column, and detection was carried out using a thermionic N–P-specific detector. The compounds were extracted from plasma with benzene with a yield of >87%. The assay was linear in the ranges of 0.001 to 0.5 and 0.5 to 25 µg/ml for CCNU or 0.003 to 0.50 and 0.5 to 25 µg/ml for BCNU, with correlation coefficients from 0.9914 to 0.9999 and coefficients of variation (CV) of <3.3%. Other antineoplastic agents did not interfere in the assay. The method was employed to study the pharmacokinetics of BCNU in rabbits. The plasma concentration-time curves were fit to a two-compartment model with a mean (SE) , , and total-body clearance of 2.898 (0.913) hr^–1, 0.1228 (0.0179) hr^–1, and 7.211 (2.862) liters/hr · kg, respectively. Further, the stability of BCNU and CCNU in solution was examined at different temperatures. Both compounds were stable in benzene or acetone (4 to 37°C) but labile in plasma even if refrigerated. The apparent rate constants for degradation of BCNU and CCNU were 0.09921 and 0.02853 hr^–1 at 4°C and 5.998 and 2.553 hr^–1 at 37°C, respectively.     

Haematotoxicity of doxorubicin and 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU) and of their association in rats

Doxorubicin is an anthracycline widely used in the treatment of leukaemias, lymphomas and solid tumors. Doxorubicin cannot pass into the cerebrospinal fluid. Nitrosoureas are known to be lipophilic and to be able to penetrate the blood-brain barrier. CCNU is a nitrosourea used to treat Hodgkin's disease, brain tumors and other solid tumors. The authors have previously reported on the nephrotoxicity and hepatotoxicity of these drugs; the present paper reports their findings on haematotoxicity in female Wistar rats. In one group 40 rats received 10 mg/kg doxorubicin. In a second group 40 rats received 20 mg/kg CCNU, and a further 40 rats received 50 mg/kg CCNU. In a third group 60 rats received the association doxorubicin 10 mg/kg plus CCNU 20 mg/kg. Blood counts were performed on days 4, 8, 15, 21 and 28 after treatment. Leucopenia and severe thrombocytopenia were noted after doxorubicin administration. A biphasic decrease in the leucocyte count was observed after CCNU treatment. More severe alterations were observed when doxorubicin and CCNU were combined. Very few data on haematological abnormalities following treatment of human patients have been published. Similarities can be seen between the haematological side-effects noted in rats and those occurring in humans treated with these cytotoxic drugs. Female Wistar rats seemed to be a good model to evaluate the haematological tolerance of anthracycline, nitrosoureas or of their association. If multiple courses of these drugs have to be administered, the evolution of haematological alterations must be known: the decrease phase of blood cells is followed by a rebound phase. The drug should be avoided during this phase of granulocyte activation.     

Synthesis of (1',2'-trans)-3-phenyl-1-[2'-(N-pyrrolidinyl)cyclohexyl]pyrrolid -2-ones as kappa-selective opiates

(1',2'-trans)-3-Phenyl-1-[2'-(N-pyrrolidinyl)cyclohexyl]pyrrolid-2 -ones (1 and 2) and their 3,4-dichlorophenyl analogues (4 and 5) were synthesized as lactam analogues of U-50,488 (I; a kappa-opiate analgesic developed by Upjohn Company). Compounds 1 and 2 were found to be oxidized by air, in the presence of a strong base, to the 3-hydroxylated derivative 3. Compound 4 gave slightly higher kappa-affinity (Ki = 10 nM) than I, with about half the kappa-selectivity (mu/kappa = 23). Compounds 1 and 3 showed weaker kappa-binding (Ki = 400 nM), with about the same kappa-selectivity as 4. Compound 5, a diastereomer of 4, gave significantly weaker and less selective kappa-binding than 4; likewise, 2 is a weaker and less selective kappa-binder than 1. The binding data of intermediate compounds having the basic skeleton of I seem to reflect the importance of lipophilicity and the detrimental effects of bulky substituents on the amide nitrogen. It is likely that the binding conformation of I at the opiate receptors approaches that of the lactam analogue 4.     

Reduction of lipid peroxidation in different rat brain areas after cabergoline treatment.

Oxidative stress and mitochondrial damage are involved in Parkinson's disease (PD). Several drugs used for PD treatment have demonstrated antioxidant properties. To evaluate the antioxidant efficacy of cabergoline, an ergot derivative with a long plasma half-life, male Wistar rats were treated with vehicle or with 2.5 mg kg(-1)and 10 mg kg(-1)of the drug three, six, or 10 times at 48-h intervals. Cabergoline decreased basal lipid peroxide levels (LPO) in the hippocampus of rats given 10 mg kg(-1)10 times, and in the striatum of rats given the same dose six or 10 times. Spontaneous LPO was inhibited in the hippocampus of rats given 10 mg kg(-1)10 times. Stimulated LPO was decreased in the striatum of rats given 10 mg kg(-1)six times and in rats given 2.5 and 10 mg kg(-1)10 times. The ability of cabergoline to reduce LPO suggests its anti-lipoperoxidative properties.     

The effect of 1-(5'-oxohexyl)-3-methyl-7-propyl-xanthine on the respiratory activity of the rat brain mitochondria

The effect of 1-(5'-oxohexyl)-3-methyl-7-propyl-xanthine (HWA 285) on the respiration and oxidative phosphorylation in mitochondria isolated from normal (CM), ischemic (IsM) and postischemic (PIsM) rat brain was investigated. After the administration of 10 mg/kg HWA 285 p.o. daily for 14 days the mitochondrial ATPase activity was significantly increased, whereas O2-consumption and the respiratory control rate (RCR) were decreased. In IsM the RCR was increased, if they consumed glutamate and malate as substrates (from 3.7 +/- 0.8 to 5.0 +/- 0.75) as consequence of increased oxygen consumption in status 3. The pretreatment of the rats with 10 mg/kg HWA 285 p.o. induced a normalization of RCR in mitochondria from ischemic brains. The RCR in PIsM was apparently not influenced by HWA 285 but the oxidative phosphorylation was slightly increased. These results are consistent with the assumption that HWA 285 exerts a modulative effect on the rat brain mitochondria dependent on their functional status.     

The effect of 1-(Indol-4-yl-oxy)-3-isopropylamino-propan-2-ol (LB-46, Visken) on carbohydrate and lipid metabolism

Summary The effect of i.v. LB-46 (Visken^®), 0.6 mg, on blood concentrations of various parameters of carbohydrate (blood sugar, lactate, pyruvate) and lipid metabolism (free fatty acids, acetoacetate, -hydroxybutyrate, triglycerides) has been studied in a double blind trial in 10 healthy subjects. There were small, but significant elevations of blood sugar and free fatty acids (p<0.05 andp<0.01). Acetoacetate, -hydroxybutyrate and triglyceride levels showed some increase. The results suggest that the drug has an intrinsic sympathicomimetic activity in the resting state.     

Inhibitory effect of Lysichiton camtschatcense extracts on Fe2+/ascorbate-induced lipid peroxidation in rat kidney and brain homogenates

Lysichiton camtschatcense is a well-known plant in Japan where it has been used as a traditional medicine by the “Ainu” people for the treatment of acute nephritis. It is presumed that L. camtschatcense has an inhibitory effect against nephritis caused by reactive oxygen species (ROS) owing to its antioxidant activities. Consequently, the antioxidant effect of L. camtschatcense extracts was assessed against Fe²⁺/ascorbic acid (AsA)-induced lipid peroxidation in rat kidney and brain homogenates. The antioxidant effect of the chloroform extract (CE) was more potent than that of the methanol extract (ME) for both homogenates. The antioxidant effect of both extracts was similar to those of α-tocopherol, a lipid-soluble antioxidant, and glutathione (GSH), a water-soluble antioxidant, which were used as reference compounds. Although CE showed a low radical-scavenging effect for superoxide anion radicals (O₂^·−) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, assessed by using an electron spin resonance (ESR) method, hydroxyl radicals (·OH) were markedly scavenged by more than 80%. On the other hand, ME showed more significant scavenging effect for DPPH radicals and O₂^·− than CE. These results suggest that the inhibitory effects of the L. camtschatcense extract on lipid peroxidation in rat kidney and brain are based on its high radical-scavenging effect against ·OH, O₂^·−, and lipid-derived radicals generated from the cell membrane.     

铅对发育中的脑脂质过氧化作用的影响

新生大鼠吸吮饮用含Pb~(2+)300 ppm和1000ppm水的母鼠乳汁(约含Pb~(2+)10～25ppm)连续21 d后,血铅和脑铅含量有显著增高,其血和脑ALAD活性亦有不同程度的抑制,说明Pb~(2+)容易由母体乳汁传递给新生大鼠引起铅中毒。另外还看到,新生大鼠脑匀浆、脑线粒体和微粒体的膜MDA含量及脂质过氧化荧光物质量比对照明显增加,血浆SOD活性抑制,均提示Pb~(2+)引起膜损伤(一是促进膜脂质过氧化作用;二是抑制SOD活性),因而出现Pb~(2+)对中枢神经系统的神经毒性。     

铅诱发大鼠脂质过氧化作用及毒作用机制研究

本研究表明，醋酸铅染毒大鼠肝和脑组织中氧自由基的信号随着染毒剂量的增高而增高，表明铅染毒可诱发大鼠体内氧自由基产生；血、肝、和脑组织中ＭＤＡ水平升高程度与染毒剂量呈极显著正相关性；红细胞内ＳＯＤ活性下降和ＧＳＨ－Ｐｘ酶活性轻度升高，使得机体清除自由基和抗氧化的能力下降，造成体内的氧自由基蓄积，从而诱发脂质过氧化作用，推测这可能是铅的毒作用机制之一。     

Endosulfan-induced lipid peroxidation in rat brain and its effect on t-PA and PAI-1: ameliorating effect of vitamins C and E

Endosulfan provokes systemic toxicity in mammals and induces reactive oxygen species (ROS) and lipid peroxidation (LPO). The brain is susceptible to LPO and several studies implicate ROS and LPO in CNS diseases. Tissue plasminogen activator (t-PA) has been accredited with plasminogen-dependent roles in the CNS, as well as plasminogen-independent functions. The aim of this study was to investigate the activities of t-PA and its inhibitor, plasminogen activator inhibitor-1 (PAI-1) in the adult rat brain, after subchronic endosulfan treatment. Furthermore, the potency of vitamins C and E to attenuate these effects was explored. Endosulfan was administered in Wistar rats either alone or with vitamin C and/or vitamin E. The induced oxidative stress was manifested by induction of LPO as determined by higher malondialdehyde levels. This was accompanied by elevation of t-PA and PAI-1 activities. Vitamins E and C, both well-known for their antioxidant properties, substantially acted in a preventive way and protected the brain from these effects.