Multiple actions of the coumarine derivative cloricromene and its protective effects on ischemic brain injury

ANTIOXIDANT ENZYMES ACTIVITY IN EXPERIMENTAL ISCHEMIA-REPERFUSION INJURY

Background. Blood loss during civil and military limb trauma is the most common cause of preventable death. Complications due to the use of a hemostatic tourniquet are widely investigated nowadays. Therefore, the standards of the past have to be improved. Objective. The aim of the research is to study the reaction of the enzyme chain of the liver antioxidant system in the presence of modifications of ischemia-reperfusion injury (IRI). Methods. 210 white male-rats, aged 5-5.5 months, were used in the research. The dynamics of antioxidant enzymes activity catalase (Cat) and superoxide dismutase (SOD) in liver tissue in cases of modifications of ischemia-reperfusion injury (IRI) were studied. The period of investigation was in 24 hours, 3, 7, 14 days after the injury. Results. In cases of simulated IRI the catalase level mainly decreased at each period of the experiment. The peak of SOD activity was evidenced on the 1st, 3rd or 7th days after the experimental IRI according to the degree of trauma severity. Thus, IRI combined with severe blood loss and mechanical trauma caused the severest affection of the antioxidant system. Even a single application of hemostatic tourniquet caused similar wavelike reactions at different times. Conclusions. The development of IRI is accompanied by a significant depression of the liver antioxidant system. The most significant changes were evidenced in cases of IRI combined with blood loss and mechanical trauma, but even a single application of a tourniquet caused active response of the antioxidant enzymes.

Serotonin involvement in Rhodiola rosea attenuation of nicotine withdrawal signs in rats

Rhodiola rosea has been used for centuries in the traditional medicine to stimulate nervous system, to enhance physical and mental performance and to treat fatigue. It is known that administration of Rhodiola rosea extract elicits antidepressant activity, but the mechanism of action still remains unclear. Evidence from animal models and human studies show that nicotine reduces symptoms of depression and that nicotine cessation induces depressive-like symptoms. We investigated the effects of Rhodiola rosea on nicotine withdrawal signs. Nicotine dependence was induced by subcutaneous nicotine injection (2 mg/kg, four times daily) for 14 days. Another group of animals treated with nicotine (for 14 days) and successively with Rhodiola rosea extract was co-administered with selective 5-HT receptorial antagonist WAY 100635 (1 mg/kg). After nicotine withdrawal animals were evaluated for behavioural parameters (locomotor activity, abstinence signs, marble burying test), diencephalic serotonin metabolism and serotonin receptor-1A expression. Results show a significant increase of 5-HT content in N treated with R. rosea, with a significant increase of serotonin receptor 1A, suggesting an involvement of serotonin in beneficial effects of R. rosea on suffering produced by nicotine withdrawal.

Interactions between endocannabinoid and serotonergic systems in mood disorders caused by nicotine withdrawal

INTRODUCTION

Endocannabinoid and serotonin systems are implicated in mechanisms underlying depression-like symptoms. Involvement of serotonin in mood disorders occurring after smoking cessation has been observed. We studied the interactions between endocannabinoid and serotonergic systems in mood and behavioral disorders caused by nicotine cessation. The effects of the endocannabinoid transport inhibitor AM404 and the cannabinoid receptor 1 antagonist AM251 in a nicotine-dependent rodent model were investigated.

METHODS

Dependence was induced by subcutaneous injections of nicotine (2 mg/kg, 4 injections daily) for 15 consecutive days in mice. Animals treated with AM404 or AM251 were tested for locomotor activity and abstinence signs 24 hr after nicotine withdrawal and in forced swimming test (FST) at different times: immediately after last nicotine injection (t = 0) and 15 and 30 days after nicotine withdrawal. In nicotine-dependent mice treated with AM404 or AM251, expression of diencephalic serotonin receptor 1(A) (5-HT1(A)) was also measured. Effects of AM404, AM251, and WAY 100635 (5-HT(1A) receptor antagonist) in mice subjected to FST were evaluated.

RESULTS

A decrease in diencephalic 5-HT(1A) levels was observed in mice previously injected with nicotine. In the same animals, AM251 caused (0.5-2 mg/kg) a significant decrease of abstinence signs and AM404 (0.5-2 mg/kg) provoked a significant dose-dependent reduction in immobility time in the FST. Either AM251 or WAY 100635 antagonized anti-immobility effects of AM404.

CONCLUSIONS

Data indicate the existence of a link between serotonergic and endocannabinoid systems in the mechanisms underlying mood disorders caused by nicotine abstinence and suggest that these interactions are potential targets for pharmacological aid in smoking cessation.

Enhancement of availability of cloricromene at brain level by a lipophilic prodrug

The pharmacokinetics of a lipophilic alkylamino acid (LAA) prodrug of cloricromene (AD6), namely CLOR-C4, was studied in rat plasma and brain. In particular, we observed that the intraperitoneal administration of CLOR-C4 to rats was able to provide a slight but statistically significant higher concentration of the active drug metabolite (cloricromene acid) in the brain compared with the parent drug administered by the same way. The correlation between pharmacokinetic data and calculated partition (LogP) and brain distribution coefficients (LogBB) supported the hypothesis that the amphiphilic nature of the LAA promoiety could be responsible for a better penetration into the brain, more than the simple increase of lipophilicity gained with respect to the parent drug.

Serotonin mediates beneficial effects of Hypericum perforatum on nicotine withdrawal signs

Antidepressants may be effective treatment for smoking cessation and new evidence on relationship between smoking and depression is emerging. Extracts of the plant Hypericum perforatum possess antidepressant activity in humans and reduce nicotine withdrawal signs in mice. Both nicotine and H. perforatum administration elicit changes in serotonin (5-HT) formation in the brain. On this basis, we investigated the possible involvement of 5-HT in the beneficial effects of H. perforatum on nicotine withdrawal signs. With the aim to induce nicotine dependence, nicotine (2 mg/kg, four intraperitoneal injections daily) was administered for 14 days to mice (NM). Saline (controls, M) or H. perforatum extract (Ph 50, 500 mg/kg) were orally administered immediately after the last nicotine injection for 30 days after nicotine withdrawal. Another group of animals treated with nicotine (14 days) and successively with H. perforatum extract was intraperitoneally co-administered with selective 5-HT receptorial antagonist WAY 100635 (WAY) (1 mg/kg). All animals were evaluated for locomotor activity and abstinence signs, 24 after nicotine withdrawal. Brain 5-HT metabolism was evaluated in the cortex of mice sacrificed 30 days after nicotine withdrawal through evaluation of 5-HT, 5-hydroxyindoleacetic acid (5-HIAA) and 5-HIAA/5-HT ratio. After nicotine withdrawal measurement of 5-HT metabolism in the cortex showed a reduction of 5-HT content while animals treated only with Hypericum extract showed a significant reduction of total abstinence score compared to controls. WAY inhibited the reduction of total abstinence score induced by H. perforatum. Moreover, 5-HT1A expression has been evaluated 30 days after nicotine withdrawal. Our results, show a significant increase of cortical 5-HT content in NM treated with H. perforatum, with a concomitant significant increase of 5-HT1A receptor. So, it is possible to suggest an involvement of 5-HT in beneficial effects of H. perforatum on suffering produced by nicotine withdrawal in dependent mice.

Long-term effects of nicotine on the forced swimming test in mice: an experimental model for the study of depression caused by smoke

Large evidence showing an association between depression and tobacco smoking is known. Nicotine is the active chemical responsible for smoking addiction, and its withdrawal may induce in smokers greater sensitivity to stress. Our aim has been to investigate the links between tobacco addiction and depression by studying the long-term effects of repeated administration of nicotine followed by dependence, to forced swimming test, serotonin content and 5-HT(1A) expression in diencephalon. Dependence has been induced by daily subcutaneous injection in mice of nicotine (2mg/kg four injections daily) for 15 days and assessed after nicotine withdrawal with an abstinence scale; control animals received daily subcutaneous injection of saline for the same period. Experiments on forced swimming test have been carried out at t=0 (last day of nicotine or saline treatment), and 15, 30, 45 and 60 days after saline or nicotine withdrawal. Both control mice and nicotine mice have been pre-treated with oral 5-hydroxy-tryptophan (12.5-50mg/kg), precursor of serotonin, before forced swimming test. Nicotine mice have shown on forced swimming test a significant increase of immobility time compared to control mice. This increase was not evident in nicotine mice treated with 5-hydroxy-tryptophan and treatment with the selective serotonin receptorial antagonist WAY 100635 (WAY) abolished 5-hydroxy-tryptophan effects. Evaluation of diencephalic serotonin, performed at t=0 showed an increase of diencephalic serotonin content, while serotonin measured 15, 30, 45 and 60 days after nicotine withdrawal, was significantly reduced in nicotine mice compared to control mice. Western blot analysis showed a great reduction of 5-HT(1A) receptor expression in nicotine mice measured at t=0 (last day of treatment) and at 15 and 30 days after nicotine withdrawal compared to control mice. Our results show that (i) behavioural alterations estimated with forced swimming test and (ii) changes in diencephalic serotonin content and 5-HT(1A) receptor expression, are present since nicotine is withdrawn even after a long time, suggesting a role of serotonin in mood disorders eventually occurring following smoking cessation.

Modulation of IL-1 beta gene expression by lipid peroxidation inhibition after kainic acid-induced rat brain injury

Brain injury was induced by intraperitoneal administration of kainic acid (KA, 10 mg/kg). Animals were randomized to receive either IRFI 042 (20 mg/kg i.p.), a lipid peroxidation inhibitor, or its vehicle (NaCl 0.9% DMSO 10% 1 ml/kg i.p.) 30 min before KA administration. A first set of animals was sacrificed 6 h after KA injection to measure malondialdehyde (MDA) content, glutathione-reduced (GSH) levels and the mRNA for interleukin-1beta (IL-1beta) in the cortex and in the hippocampus. A second set of animals was sacrificed 48 h after KA administration for histological analysis. All animals were observed for monitoring the behavioral sequelae and for evaluating latency of convulsions. Sham brain injury rats were used as controls. Intraperitoneal administration of IRFI 042 significantly decreased brain MDA (cortex: KA + vehicle = 0.285 +/- 0.04 nmol/mg protein; KA + IRFI 042 = 0.156 +/- 0.02 nmol/mg protein, P < 0.005; hippocampus: KA + vehicle = 0.350 +/- 0.03 nmol/mg protein; KA + IRFI 042 = 0.17 +/- 0.04 nmol/mg protein, P < 0.005), prevented the brain loss of GSH in both cortex (KA + vehicle = 7.81 +/- 1 micromol/g protein; KA + IRFI 042 = 12.1 +/- 1 micromol/g protein; P < 0.005) and hippocampus (KA + vehicle = 5 +/- 0.8 micromol/g protein; KA + IRFI 042 = 9.4 +/- 1.8 micromol/g protein; P < 0.005), reduced both brain IL-1beta mRNA expression and oedema, and increased latency of convulsions. Histological analysis showed a reduction of cell damage in IRFI 042-treated samples. The present data indicate that lipid peroxidation inhibition reduces IL-1beta gene expression and protects against kainic acid-induced brain damage.

Preparation and characterization of solid lipid nanoparticles containing cloricromene

This article describes the development of solid lipid nanoparticles (SLN) as colloidal carriers for cloricromene. Nanoparticles were prepared by the microemulsion or precipitation technique. In vitro drug release profile from SLN was studied under various experimental conditions mimicking some body fluids. The drug release rate of drug at pH 7.4 and human plasma is high. In plasma, after 15 min, about 70% of drug was released. The cloricromene that was not released within 4 hr was found in the SLN. This result suggests that this colloidal system could be useful for targeted drug delivery to the central nervous system after intravenous administration.

Hypericum perforatum attenuates nicotine withdrawal signs in mice

RATIONALE

Hypericum perforatum is used as a natural antidepressant, and other antidepressants have been marketed to aid in smoking cessation.

OBJECTIVE

We investigated the effects of an extract of Hypericum perforatum (Ph-50) on withdrawal signs produced by nicotine abstinence in mice.

METHODS

Nicotine (2 mg/kg, four injections daily) was administered for 14 days to mice. Different doses of Ph-50 (125-500 mg/kg) were administered orally immediately after the last nicotine injection. In another experiment, Ph-50 (500 mg/kg) was orally administered in combination with nicotine, i) starting from day 8 until the end of the nicotine treatment period, or ii) during nicotine treatment and after nicotine withdrawal, or iii) immediately after the last nicotine injection. On withdrawal from nicotine, all animals were evaluated for locomotor activity and abstinence signs.

RESULTS

The locomotor activity reduction induced by nicotine withdrawal was abolished by Ph-50, which also significantly and dose-dependently reduced the total nicotine abstinence score when injected after nicotine withdrawal.

CONCLUSIONS

These data show that treatment with Hypericum perforatum attenuates nicotine withdrawal signs in mice. Further studies are necessary to test the possibility that it may be used for smoking cessation treatment in humans.

Transcriptional suppression of the HIV promoter by natural compounds

Tannins and lignins are natural compounds contained in plants such as tea leaves. Previously, we demonstrated that tannic acid represses 12-o-tetra-decanoyl phorbol-13-acetate (TPA)-induced human immunodeficiency virus (HIV) promoter activity. Furthermore, we demonstrated that a 30-bp element located just downstream of the NF-kappaB element in the HIV promoter responds negatively to tannic acid. However, the kinds of molecules responsible for this suppressive effect have remained unknown, because tannic acid is a mixture of various galloylglucoses. Here, we examined structure-defined natural compounds for HIV promoter-suppressive effects. We found that ellagitannins suppress TPA-induced HIV promoter activity to the same extent as tannic acid. 3-phenylcoumarins, isoflavone and chalcones have more suppressive effects than ellagitannins. On the other hand, other flavonoids and acetogenins have no suppressive effect. 3-phenylcoumarins and chalcones showed no suppressive effect on the cytomegalovirus (CMV) promoter, suggesting that they act specifically on the HIV promoter. These results suggest that 3-phenylcoumarin or chalcone compounds could be used to develop novel anti-HIV drugs with an action targeted at HIV promoter activity.

Erythropoietin protects against brain ischemic injury by inhibition of nitric oxide formation

Erythropoietin prevents in vitro glutamate-induced neuronal death and could play a role in the central nervous system. We investigated the in vivo effects of recombinant human erythropoietin after intraperitoneal (i.p.; 25-100 U) or intracerebroventricular (i.c.v.; 0.25-25 U) administration on survival, brain malonildialdehyde (MDA) levels, brain edema, hippocampal neuronal death and brain nitric oxide (NO) synthesis after bilateral carotid occlusion (5 min), followed by reperfusion in the Mongolian gerbil. Peripheral posttreatment with recombinant human erythropoietin reduced postischemic MDA levels, brain edema and increased survival. Either peripheral or i.c.v. posttreatment with recombinant human erythropoietin significantly reduced hippocampal CA1 neuronal loss, observed 7 days after the ischemic event. Increase of nitrite and nitrate (as an index of NO formation) in the hippocampus, as observed after ischemia, was reduced in animals treated with recombinant human erythropoietin. These data suggest that in vivo recombinant human erythropoietin effects on brain ischemic injury could be due to inhibition of NO overproduction.