5-Aminolevulinic Acid Enhances Ultrasound-mediated Antitumor Activity via Mitochondrial Oxidative Damage in Breast Cancer

BACKGROUND/AIM

5-Aminolevulinic acid (5-ALA), a precursor of protoporphyrin IX (PpIX), is now used for photodynamic therapy (PDT) of pre-cancers of the skin and photodynamic diagnosis (PDD) of brain tumors. Sonodynamic therapy (SDT) of cancers with ultrasound has been studied using 5-ALA as a sonosensitizer. In this article, we evaluated the sonosensitizing activity and mode of action of 5-ALA/PpIX by using mouse mammary tumor EMT6 cells.

RESULTS

5-ALA-SDT showed significant antitumor effects toward EMT6 cells in vitro and in vivo. The fluorescence of MitoSOX Red, an indicator specific for mitochondrial superoxide, was significantly increased by 5-ALA-SDT. Moreover, the fluorescence derived from JC-1, an indicator of mitochondrial membrane potential, was also significantly increased by 5-ALA-SDT. These findings suggest that mitochondria are one of the target organelles of 5-ALA-SDT. PpIX enhanced reactive oxygen species (ROS) production from tert-butyl hydroperoxide (tBHP), suggesting that PpIX might stabilize or promote ROS generation from tBHP.

CONCLUSION

5-ALA-SDT showed an antitumor effect in mouse mammary tumor EMT6 cells through oxidation of the mitochondrial membrane via ROS production.

Evaluation of the sonosensitizing activities of 5-aminolevulinic acid and Sn(IV) chlorin e6 in tumor-bearing chick embryos

BACKGROUND

Recently, 5-aminolevulinic acid (5-ALA), precursors of protoporphyrin IX (PpIX), and Sn(IV) chlorin e6 (SnCe6) have been proposed as possible sonosensitizers for sonodynamic therapy of cancer. Therefore, we evaluated the pharmacokinetic properties and sonosensitizing activities of 5-ALA and SnCe6 in vivo by using the EMT6/KU tumor-bearing chick embryos.

RESULTS

The concentration of PpIX in tumor and liver tissues and serum increased in a time-dependent manner after the i.v. administration of 5-ALA; PpIX concentrations reached their peak level after 5-7 h. The concentration of SnCe6 reached its maximum value in the tumor tissue and serum immediately after i.v. administration. The combined treatment of 5-ALA or SnCe6 with ultrasound irradiation showed a significant antitumor effect towards EMT6/KU solid tumors.

CONCLUSION

We evaluated the pharmacokinetic properties and sonosensitizing activities of 5-ALA and SnCe6 in a chick embryo model and found that 5-ALA might be more suitable as a sonosensitizer than SnCe6.

Effects of 5-HT(4) receptor agonists, cisapride and mosapride citrate on electrocardiogram in anaesthetized rats and guinea-pigs and conscious cats

The purpose of this study was to examine the arrhythmogenic potential of 5-HT4 receptor agonists, cisapride and mosapride citrate (mosapride) in vivo. In anaesthetized rats, cisapride at intravenous infusion of 10 and 30 mg/kg/hr for 1 hr prolonged the electrocardiographic RR and QT intervals, whereas at 3 mg/kg/hr, it prolonged the RR interval without affecting the QT interval. Mosapride at 30 mg/kg/hr for 1 hr slightly, but not significantly, prolonged the QT interval. In anaesthetized guinea-pigs, cisapride at intravenous infusion of 0.3, 1 and 3 mg/kg over 15 min. prolonged the RR interval (18-44%), QT interval (18-42%) and the corrected QT interval (QTc; 8-19%). Mosapride at 3, 10 and 30 mg/kg over 15 min. little affected the QTc although at 30 mg/kg, it slightly prolonged the RR and QT intervals. With repeated oral administrations of 30 mg/kg twice a day for 7 days, cisapride prolonged the QT interval (11-35%) and QTc (11-32%) at the 3rd and 7th days in conscious cats. In addition, cisapride depressed the ST segment in two out of five cats. Mosapride at 60 mg/kg twice a day for 7 days did not affect the QT interval or QTc in cats. The maximal plasma concentrations of mosapride and its main metabolite (a des-4-fluorobenzyl-mosapride) at the 7th day in cats were 9.4+/-2.8 microM and 2.5+/-0.3 microM , respectively, being 100 and 30-60 times higher than those in man given therapeutic doses (Sakashita et al. 1993a&b). These results indicate that mosapride has little arrhythmogenic potential.

Simultaneous determination of the histamine H1-receptor antagonist ebastine and its two metabolites, carebastine and hydroxyebastine, in human plasma using high-performance liquid chromatography

Ebastine (CAS 90729-43-4) is an antiallergic agent which selectively and potently blocks histamine H1-receptors in vivo. A simple and sensitive high-performance liquid chromatography (HPLC) method is described for the simultaneous determination of ebastine and its two oxidized metabolites, carebastine (CAS 90729-42-3) and hydroxyebastine (M-OH), in human plasma. After a pretreatment of plasma sample by solid-phase extraction, ebastine and its metabolites were analyzed on an HPLC system with ultraviolet detection at 254 nm. Chromatography was performed on a cyano column (250x4.0 mm I.D.) at 40 degrees C with the mobile phase of acetonitrile-methanol-0.012 M ammonium acetate buffer (20:30:48, v/v/v) at a flow rate of 1.2 ml/min. Accurate determinations were possible over the concentration range of 3-1000 ng/ml for the three compounds using 1 ml plasma samples. The intra- and inter-day assay accuracy of this method were within 100+/-15% of nominal values and the precision did not exceed 12.4% of relative standard deviation. The lower limits of quantitation were 3 ng/ml for ebastine and its metabolites in human plasma. This method was satisfactorily applied to the determination of ebastine and its two oxidized metabolites in human plasma after oral administration of ebastine.

The effects of diazepam on sleep spindles: a qualitative and quantitative analysis

The effects of 2.5 or 5 mg diazepam (DIZ) on the sleep spindles were studied in 12 healthy male subjects. Polygraphic recordings and the state anxiety scale of the State Trait Anxiety Inventory (STAI) were made for 6 consecutive nights. An inert placebo was given on the first 3 nights and on the sixth night, and DIZ was administered on the fourth and fifth nights. DIZ produced increases in the amount of the slow and fast spindles in a dose-dependent manner. DIZ dose-dependently lowered the frequency of the fast spindles and elevated that of the slow spindles. Furthermore, the influence of DIZ on fast spindles was greater than that on slow spindles. DIZ decreased the state anxiety of the subjects in a dose-dependent manner. These results suggest that measuring the amount and the frequency of fast spindles could be a useful tool in predicting the anxiolytic effects of benzodiazepines.

Effects of pertussis toxin on behavioral responses during different withdrawal periods from chronic cocaine treatment

1. The role of Gi-proteins on cataleptic responses induced by SCH23390 and haloperidol in chronic cocaine-treated mice was examined by intracerebroventricullor (i.c. v.) and intravenous (i. v.) injections of pertussis toxin (PTX), which catalyzes adenosine diphosphate (ADP)-ribosylation of Gi-proteins. 2. In animals pretreated chronically with cocaine (10 mg/kg, s.c. on alternating days for 21 days), haloperidol (0.1 mg/kg i.p.) exerted an enhanced cataleptic response, but SCH23390 (0.1 mg/kg i.p.) produced an attenuated response at day 1, which converted to a supernormal response, when it was administered 20 days after the last cocaine injection. 3. The attenuated SCH23390 cataleptic response (D1 receptor supersensitivity induced one day after chronic cocaine treatment), was reversed one day after a single dose of PTX, which by itself had no effect, whereas the enhanced haloperidol catalepsy was further enhanced with same dose of toxin. 4. On the other hand, the enhanced SCH23390- and haloperidol-induced cataleptic responses seen during longer withdrawal period (20 days) were potentiated 20 days after a single coadministration of PTX. The stimulatory effects of PTX on the enhanced SCH23390-induced cataleptic response (D1 receptor subsensitivity induced during long-term withdrawal periods from chronic cocaine treatment), may be due to an indirect inhibition of D1 receptors (a synergistic effect) via blockade of postsynaptic dopamine D2 receptors. 5. The postsynaptic D1 receptor supersensitivity and D2 receptor subsensitivity induced one day after chronic cocaine treatment may involve greater Gi-protein ADP-ribosylation in the presynaptic cell body (VTA) than that in the postsynaptic cell body. On the other hand, the subsensitivity of postsynaptic dopamine D1 and D2 receptors (the enhanced SCH23390- and haloperidol-induced cataleptic responses) seen during longer withdrawal periods may mainly involve Gi-protein ADP ribosylation in the postsynaptic cell body, and which may be mediated by a PTX-sensitive muscarinic M2 and/orGABAB receptor activation.

Appearance of frontal midline theta activity in patients with generalized anxiety disorder

The appearance of frontal midline theta activity (Fmθ), recognized as distinct EEG theta rhythm in the frontal midline area during performance of a mental task, reflects feelings of relief from anxiety in humans. In the present study, EEGs were recorded, and the Hamilton Rating Scale for Anxiety and the state anxiety scale of Spielberger's State-Trait Anxiety Inventory were evaluated once a week in 28 patients with generalized anxiety disorder. The Taylor Manifest Anxiety Scale and the trait anxiety scale of Spielberger's State-Trait Anxiety Inventory were used to assess anxiety before and after the tests. The present results suggest that the appearance of Fmθ might be closely related to an improvement in the anxiety symptoms associated with generalized anxiety disorder.

A polysomnographic study of sleep patterns in normal humans with low- or high-anxiety personality traits

To clarify the effects of anxiety-related personality traits on sleep patterns, polysomnographic examinations (PSG) were performed over 4 consecutive nights on normal humans who tested within the low- or high-anxiety ranges. The subjects consisted of two groups of six male university students who scored either less than 45 points (low-anxiety group) or more than 55 points (high-anxiety group) on the Spielberger's State Trait Anxiety Inventory. Compared to the levels of sleep change in the high-anxiety group, the low-anxiety group exhibited a greater change in REM sleep and stage 2 sleep. The REM sleep in the low-anxiety group was shorter on the first and second nights compared to the third and fourth nights, and the stage 2 sleep was longer on the first night than on the remaining three nights. Thus, the low-anxiety group showed a first-night effect followed by partial recovery on the second night, while the high-anxiety group exhibited no obvious first-night effect. These results suggest that there is a difference in sleep patterns, assessed by consecutive PSG, between those with low- and high-anxiety traits, and that anxiety-related personality traits attenuate the occurrence of the first-night effect, reflecting a lower adaptability to a novel environment.

Modification of cataleptic responses to dopamine receptor antagonists after withdrawal from chronic cocaine or cocaine plus dopamine antagonist administration

1. In mice pretreated chronically with cocaine (indirect dopamine agonist: 10 mg/kg, s.c. on alternating days for 15 days), haloperidol (dopamine D2 antagonist: 0.3 mg/kg i.p.) exerted an enhanced cataleptic response, but SCH23390 (dopamine D1 antagonist: 0.3 mg/kg i.p.) produced an attenuated response at 24 h, which converted to a supernormal response, when it was administered 15-60 days after withdrawal from cocaine. 2. A challenge dose of SCH23390 exhibited enhanced catalepsy when given 15 days, but not at 24 h, after the last pretreatment dose of SCH23390 (0.1-1.0 mg/kg s.c.). In contrast, haloperidol catalepsy was not affected by the SCH23390 pretreatment. 3. However, in animals chronically pretreated with haloperidol (0.1-1.0 mg/kg s.c.), a challenge dose of SCH23390 as well as haloperidol exhibited attenuated cataleptic effects at 24 h and normal cataleptic responses at 15 days after the last dose of the pretreatment regimen. 4. Challenge doses of haloperidol or SCH23390 given to mice 24 h after chronic cocaine pretreatment produced enhanced and attenuated cataleptic responses, respectively; however, these responses were no longer produced when haloperidol or SCH23390 was given to mice pretreated chronically with a combination of cocaine and either haloperidol or SCH23390. 5. The enhanced catalepsy produced by a challenge dose of SCH23390 (15-60 days after chronic cocaine) was further potentiated when it was administered to animals that had been pretreated chronically with a combination of SCH23390 and cocaine, but was antagonized in animals pretreated chronically with haloperidol and cocaine. In contrast, the degree of enhanced cataleptic responses produced by a challenge dose of haloperidol 30-60 days after pretreatment chronically with a combination of cocaine + SCH23390 was similar to that seen after chronic cocaine alone. However, this enhanced response was antagonized in animals that had been pretreated chronically with the combination of cocaine + haloperidol. 6. The results suggest that the coadministration of SCH23390 with cocaine was able to block indirectly dopamine D2 receptor inhibition (subsensitivity) induced during the early withdrawal period from chronic cocaine, despite the fact that by itself SCH23390 did not have an effect on haloperidol catalepsy. Accordingly, the stimulatory effects of dopamine D2 receptors by a single administration of cocaine may be mediated mainly by an indirect stimulation of dopamine D2 receptor function via its D1 receptor stimulating action. 7. The coadministration of SCH23390 with cocaine rather aggravate the subsensitive effect of dopamine D1 receptors (increased SCH23390 catalepsy) produced during long-term withdrawal period from chronic cocaine, but did not affect that of the dopamine D2 receptor. On the other hand, the coadministration of haloperidol with cocaine normalized both D1 and D2 receptor subsensitive effect. 8. These result suggest that a single administration of SCH23390 or haloperidol after long-term withdrawal periods from chronic cocaine may not be effective as antipsychotic drugs because of further aggravation of suppressive behaviors. These results also provide evidence that D2 receptor antagonists may be more effective as antipsychotic drugs than dopamine D1 receptor antagonist, since the coadministration of haloperidol with cocaine normalized the abnormal behaviors seen during early and long-term withdrawal periods from chronic cocaine.

Anxiolytic effects of low-dose clomipramine in highly anxious healthy volunteers assessed by frontal midline theta activity

1. The appearance of Fm theta, the distinct EEG theta rhythm in the frontal midline area during performance of a mental task, reflects relief from anxiety in humans. 2. In the present study, the anxiolytic effects of low-dose clomipramine were examined by monitoring the Fm theta amount, the STAI scores and the plasma 5-HIAA concentration in 24 male university students with (Fm theta group, n = 12) and without (non-Fm theta group, n = 12) Fm theta. 3. Subjects were given placebo, 10 mg and 30 mg clomipramine in a double-blind crossover design. Blood samples were obtained, STAI scores were determined, and EEGs were recorded before and during the performance of an arithmetic addition task. The test was repeated twice: before and 3 hrs after drug administration. 4. In the non-Fm theta group, 10 mg clomipramine decreased the 5-HIAA concentration and state anxiety scores but increased the Fm theta amount, while 30 mg clomipramine slightly increased only the Fm theta amount. However, there were no differences in these items before and after clomipramine administration in the Fm theta group. 5. These results suggest that low doses of clomipramine such as 10 mg may exert anxiolytic effects during the acute phase of treatment in highly anxious humans.

Vitamin B12 treatment for delayed sleep phase syndrome: a multi-center double-blind study

The active form of vitamin B12 (methylcobalamin) has been reported to be effective on sleep-wake rhythm disorders. Previous studies, however, were performed under open trial, and the effect of vitamin B12 has not been properly evaluated. The aim of this double-blind study was to investigate the efficacy of methylcobalamin on delayed sleep phase syndrome (DSPS). Methylcobalamin (3 mg/day) or placebo was administered for 4 weeks. The subjects were 50 patients with DSPS aged 13-55 years (26.8 +/- 1.3), 27 of whom received the active drug while 23 received the placebo. No significant differences were observed between the 2 groups in subjective evaluations of mood or drowsiness during the daytime or in night sleep by sleep-log evaluation. These results indicate that 3 mg methylcobalamin administered over 4 weeks is not an effective treatment for DSPS.

Dopaminergic and cholinergic interaction in cataleptic responses in mice

The cataleptogenic effects of haloperidol, a dopamine D2 receptor antagonist; SCH23390, a D1 receptor antagonist; physostigmine, a cholinesterase inhibitor; and pilocarpine, a muscarinic M1 receptor agonist, were challenged by pretreatment of mice with SKF38393, a dopamine D1 receptor agonist; apomorphine, a dopamine D1/D2 receptor agonist (mainly D2 receptor); pirenzepine, a muscarinic M1 receptor antagonist; and scopolamine, a muscarinic M1/M2 receptor antagonist. The effect of physostigmine and pilocarpine on haloperidol and SCH23390 cataleptic responses was also examined. Each of the challenging agents blocked one or more of the cataleptogenic agents, but only scopolamine blocked all four. Pirenzepine blocked cataleptic responses induced by SCH23390 and pilocarpine, but not those by haloperidol and physostigmine. The results of this study suggest that the action of physostigmine (endogenous acetylcholine) on M2 receptors might be more potent than that on muscarinic M1 receptors. A further interesting observation was that the haloperidol-induced catalepsy was enhanced by physostigmine pretreatment, but not by pilocarpine pretreatment, whereas the SCH23390-induced catalepsy showed the opposite spectrum of enhancement by the two cholinergic agonists. We conclude that, although the four cataleptogenic agents act via the dopaminergic-cholinergic systems, their pharmacological differences may be due largely to the different receptor subtypes that are involved in the mediation of catalepsy produced by each agent. Thus, dopamine receptors not only influence the cholinergic muscarinic receptors, but muscarinic M1 and M2 receptors also might mediate dopamine D1 and D2 receptor responses, respectively. The results suggest that there are, at the least, relationships between muscarinic M1 receptors and dopaminergic D1 receptors, and between muscarinic M2 receptors and dopaminergic D2 receptors. Dopamine D1 and D2 receptors may interact in a synergistic fashion on dopaminergic systems, but act independently of each other in influencing other system such as cholinergic neurons.

Simultaneous enantiomeric determination of a gastroprokinetic agent mosapride citrate and its metabolite in plasma using alpha 1-acid glycoprotein HPLC column

Mosapride citrate, a novel benzamide-type gastroprokinetic agent, is clinically prescribed as a racemate and is metabolized to its des-4-fluorobenzyl structure (M-1). In order to analyze simultaneously the enantiomers of mosapride and M-1 in plasma, a simple and reproducible high-performance liquid chromatographic (HPLC) method has been developed. The enantiomeric separation and determination were successfully achieved using an alpha 1-acid glycoprotein column and gradient elution with a fluorimetric detection (excitation 314 nm/emission 352 nm). Both enantiomers of mosapride and M-1 were well separated between 20 and 22 min at pH 4.4 and between 4 and 7 min at pH 5.0, respectively. Accurate determinations are possible in the concentration ranges of 10-5000 ng ml-1 for mosapride enantiomers and 50-5000 ng ml-1 for M-1 enantiomers. The intra- and inter-day coefficients of variation are satisfactory for the pharmacokinetic study of mosapride.

Differential effects of dopaminergic drugs on anxiety and arousal in healthy volunteers with high and low anxiety

1. The appearance of frontal midline theta activity (Fm theta), the distinct EEG theta rhythm in the frontal midline area during performance of a mental task, indicates relief from anxiety in humans. 2. The authors examined the effects of bromocriptine and sulpiride on anxiety and arousal in 24 male university students with (Fm theta group, n = 12) and without (non-Fm theta group, n = 12) Fm theta. Subjects were given placebo, 2.5 mg bromocriptine and 100 mg sulpiride in a double-blind crossover design. 3. Blood samples were obtained, STAI scores were determined, and EEGs were recorded before and during the performance of an arithmetic addition task. The test was repeated twice: before and 1 hr after drug administration. 4. Bromocriptine reduced the HVA concentration in both groups; sulpiride caused an increase in both groups. In the Fm theta group, bromocriptine did not alter the appearance time of Fm theta, the state anxiety score or the task performance; sulpiride increased the Fm theta amount and reduced the state anxiety but did not affect the task performance. In the non-Fm theta group, bromocriptine increased the Fm theta duration and reduced the state anxiety score but did not influence the task performance, while sulpiride reduced Fm theta and increased the state anxiety but had no effect on the task performance. 5. These results suggest that the sensitivity of presynaptic D2 receptors is higher in high-anxiety subjects compared with low-anxiety subjects, and that anxiolytic effects in high-anxiety humans and those in low-anxiety humans may be caused by decreased and increased DA activity, respectively. In addition, the stimulation of DA function may cause anxiogenic effects in high-anxiety individuals.

Effects of dopamine antagonists on changes in spontaneous EEG and locomotor activity in ketamine-treated rats

We investigated the effects of dopamine antagonists on spontaneous cortical and hippocampal electroencephalographic (EEG) changes, and on hyperlocomotion in ketamine-treated rats. Ketamine (20-60 mg/kg IP) synchronized cortical EEG and desynchronized hippocampal EEG in a dose-dependent manner indicating that the drug induced a dissociation between the cortical and hippocampal EEG. These EEG changes were accompanied by an increase in spontaneous locomotor activity, which involved lack of focused direction, stereotypy, irritability and other abnormalities. Dopamine antagonists, such as haloperidol (0.3-1 mg/kg IP), and nemonapride (0.3-1 mg/kg IP), reversed the dissociation between the cortical and hippocampal EEG in ketamine (60 mg/kg IP)-treated rats. Ketamine-induced hyperlocomotion was also decreased by administration of haloperidol (0.3 and 1 mg/kg IP) or nemonapride (0.1-1 mg/kg IP). Thus, it was found that dopamine antagonists reversed the EEG alterations and behavioural changes in ketamine-treated rats.

Differential effects of noradrenergic drugs on anxiety and arousal in healthy volunteers with high and low anxiety

1. The appearance of frontal midline theta activity (Fm theta), the distinct EEG theta rhythm in the frontal midline area during performance of a mental task, indicates relief from anxiety in humans. 2. The authors investigated the effects of clonidine and yohimbine on anxiety and arousal in 24 male university students with (Fm theta group, n = 12) and without (non-Fm theta group, n = 12) Fm theta. Subjects received placebo, 0.15 mg clonidine and 15 mg yohimbine in a double-blind crossover design. 3. Blood samples were obtained, state-trait anxiety inventory (STAI) scores were determined, and EEGs were recorded before and during the performance of an arithmetic addition task. The test was repeated twice: before and 1 hr after drug administration. 4. Clonidine reduced the 3-methoxy-4-hydroxyphenylglycol (MHPG) concentration in both groups; yohimbine caused an increase in both groups. In the Fm theta group, clonidine reduced the appearance time of Fm theta and the number of task performance but did not alter the state anxiety scores; yohimbine had no effects on Fm theta or the state anxiety but increased the task performance. In the non-Fm theta group, clonidine increased the Fm theta amount and reduced the state anxiety score but did not affect task performance, while yohimbine reduced Fm theta but increased the state anxiety, the task performance and the number of errors. 5. These results suggest that changes in noradrenaline (NA) activity affect both anxiety and arousal levels in high-anxiety humans, but predominantly affect only the arousal level in low-anxiety humans.

Intermolecular interactions of antimicrobial fluoroquinolones with purified rat liver CYP1A2 studied by proton nuclear magnetic resonance spectroscopy

1. Binding and inhibition of antimicrobial fluoroquinolones towards liver CYP1A2 purified from 3-methylcholanthrene-treated rats were investigated using proton nuclear magnetic resonance (nmr) and phenacetin metabolism. 2. The proton nmr longitudinal relaxation rate study indicated that the paramagnetic effects of the haem iron of CYP1A2 were observed in protons of enoxacin with a 1,8-naphthyridine skeleton and its 4'-nitrogen atom on the 7-piperazine ring probably participated in specific binding to the haem iron. These data suggest a facile accessibility and strong binding of enoxacin to the active site of the enzyme. On the contrary, the binding region of norfloxacin with a quinoline skeleton could not be specified, and an 8-fluorinated derivative (AT-3970) had much lower paramagnetic effects and no specific binding region. 3. In a reconstituted CYP1A2 system, enoxacin exhibited the most potent inhibition of phenacetin O-deethylation. The metabolism was less inhibited by norfloxacin, and AT-3970 had a weak inhibitory activity. 4. The binding ability of the fluoroquinolones to the CYP1A2 active site is likely to determine their inhibitory activity against phenacetin metabolism.

Structure-related inhibitory effect of antimicrobial enoxacin and derivatives on theophylline metabolism by rat liver microsomes

Enoxacin, an antimicrobial fluoroquinolone with a 7-piperazinyl-1, 8-naphthyridine skeleton, is a potent inhibitor of cytochrome P-450-mediated theophylline metabolism. The present study was designed to clarify, using seven enoxacin derivatives, the molecular characteristics of the fluoroquinolone responsible for the inhibition. Three derivatives with methyl-substituted 7-piperazine rings inhibited rat liver microsomal theophylline metabolism to 1,3-dimethyluric acid to an extent similar to that of enoxacin (50% inhibitory concentrations [IC50s] = 0.39 to 0.48 mM). 7-Piperazinyl-quinoline derivatives, 8-hydroenoxacin (8-Hy) and 1-cyclopropyl-8-fluoroenoxacin (8-F1), which have a hydrogen and a fluorine at position 8, respectively, more weakly inhibited metabolite formation (IC50s = 0.88 and 1.29 mM, respectively). Little inhibition (IC50 > 2 mM) was observed in those with 3'-carbonyl and 4'-N-acetyl groups on the piperazine rings. The substrate-induced difference spectra demonstrated that the affinities of enoxacin, 8-Hy, and 8-F1 to cytochrome P-450 were parallel with their inhibitory activities. The substituent at position 8 was found to determine the molecular conformations of the fluoroquinolones, and the planarity in molecular shape decreased in the same order as the inhibitory activity (enoxacin > 8-Hy > 8-F1). Moreover, the 3'-carbonyl and 4'-N-acetyl groups decreased the basicity of their vicinal 4'-nitrogen atoms when judged from their electrostatic potentials, which showed a remarkably broadened negative charge around the nitrogens. As a result, the planarity of the whole molecule and the basicity of the 4'-nitrogen atom of enoxacin are likely to be dominant factors in the inhibition of theophylline metabolism by cytochrome P-450.

Pharmacokinetic interactions related to the chemical structures of fluoroquinolones

Fluoroquinolone derivatives interact with methylxanthines (theophylline, caffeine) and metallic ion-containing drugs to different degrees. The rat appears to be a suitable model for predicting such interactions in man. It has been possible to determine the relationship between the chemical structure of the fluoroquinolone and the magnitude of the interaction. Fluoroquinolones with a bulky substituent at the position 8, such as sparfloxacin, lomefloxacin and fieroxacin, are less prone to interact with theophylline than those without an 8-substituent, such as enoxacin. This substituent determines the planarity of the whole fluoroquinolone molecule and the interaction tends to be more significant for planar fluoroquinolones. Furthermore, a 4'-nitrogen atom in the 7-piperazinyl group is essential for the interaction to occur. The nitrogen atom is possibly the site that binds cytochrome P-450, which catalyses theophylline metabolism. The reduction in bioavailability of fluoroquinolones by concurrent administration of aluminium hydroxide is more striking for derivatives with fewer substituents on the essential structure and on the piperazinyl group, such as norfloxacin, ciprofloxacin and enoxacin. Substitution at the 5-position diminishes the interaction, which suggests that the 5-substituent may affect the formation and/or stability of unabsorbable chelate complex which is the probable cause of the interaction. These findings are potentially useful in designing fluoroquinolones less prone to drug interactions.

Effects of chronic methamphetamine on SCH23390- or haloperidol-induced catalepsy, and effects of coadministration of SCH23390 or haloperidol in mice

The influence of chronic treatment of mice with methamphetamine, an indirect dopamine agonist, on the cataleptic effects of R-(+)-chloro-2,3,4,5,-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepin -7ol hydrochloride (SCH23390), a D1 receptor agonist, or haloperidol, a mainly D2 antagonist, was investigated. Once every other day treatment with 3 mg/kg SC methamphetamine for 15 days resulted in an increase in the catalepsy produced by haloperidol (0.3 mg/kg IP) (haloperidol catalepsy), but in a decrease in the catalepsy produced by SCH23390 (0.3 mg/kg IP) (SCH23390 catalepsy), 24 h and 7 days after withdrawal of methamphetamine. These effects of chronic methamphetamine were antagonized by coadministration of either SCH23390 (0.5 mg/kg SC) or haloperidol (1.0 mg/kg SC). These results suggest that the decreased responsiveness to SCH23390 in chronic methamphetamine-pretreated mice results from a supersensitivity of D1 receptors, and that the increased responsiveness to haloperidol catalepsy results from a subsensitivity of D2 receptors. The attenuated response to SCH23390 may be interpreted as an example of sensitization to methamphetamine, and the enhanced haloperidol response as an example of tolerance to methamphetamine, based on the development of supersensitivity and subsensitivity of D1 and D2 receptors, respectively, after chronic methamphetamine administration. Furthermore, it is suggested that coadministration of either SCH23390 or haloperidol could prevent the development of D1 receptor supersensitivity and D2 receptor subsensitivity induced by chronic methamphetamine.

An automatic sleep-stage analysis system with off-line high-speed processing using a super mini-computer

An automatic sleep analysis system using a super mini-computer was developed. The system improved and expanded the data processed by the mini-computer. It had the following features: 1) wave-forms were collected and analyzed at a high speed (reproduced at 10 or 20 times the speed of a data recorder) by an off-line procedure to utilize the computer resources more efficiently; 2) all information and the original wave-forms were output to a laser printer because of the lower cost and more efficient arrangement of the data; 3) various wave-form parameters were measured by wave-form analysis; 4) the application program was based on general-purpose language; and 5) wave-form reanalysis and reconstruction of the logic was easily implemented for automatic evaluation of the sleep stages. Automatic analysis of the sleep stages was impossible for 15 of 1484 periods (20 sec per period) with one of the cases analyzed, and 142 of 1484 periods had to be corrected because of erroneous identification.

Automatic analysis of sleep spindles--assessment in one case treated with a benzodiazepine anxiolytic drug

Wave-form analysis and detection of sleep spindles should be automatically performed to achieve objective and highly precise determination of the pattern of appearance of sleep spindles. The conditions for constructing the automatic analysis and detection are as follows: 1) it is recommended that EEGs be sampled at 500 Hz or higher intervals; 2) the digital filter with the threshold that is most appropriate for removal of artifacts should be used; 3) various conditions for the analysis and detection of wave-forms are widely used; and 4) a procedure for inspecting and reading record paper should also be included in the set-up. Taking these points into consideration, the authors developed an automatic analysis system for sleep spindles, which employs a computer. The system was applied to a case preliminarily treated with a benzodiazepine anxiolytic drug, ethyl loflazepate (CM6912). The assessment using this system revealed that the CM6912 administration induced an increase in sleep spindles, delayed frequency, and caused amplitude increases and a prolonged duration.

Analysis of sleep EEGs by the interval histogram method--validity of the baseline night as a control and the effect of ethyl loflazepate (CM6912)

The effects of an anxiolytic drug, ethyl loflazepate (CM6912) on sleep EEGs were investigated by the interval histogram method originally developed. EEGs were classified into each of the delta 2-beta 2 and sigma 1 wave-form parameters, and the individual frequencies were determined on the third baseline, second drug and the first recovery nights in each sleep stage. In comparison with the second baseline night, the sigma 1 waves in stage 2 sleep and the delta 1 waves in REM sleep were decreased and the alpha and sigma 1 waves in stage 3 sleep were increased on the third baseline night. In consideration of the 5% significance level and the remarkable influence of drug administration, described below, no major problems were encountered in the use of the night as a control in this experimental schedule. The main characteristics of administration of CM6912 manifested as decreases in the slow wave, increases in the fast wave, and an increase in the sigma 1 wave in sleep stages other than stage 1. These tendencies were remarkable on the second drug night and were still evident even on the recovery night. Increases in sigma 1 wave were related to increases in sleep spindles. The increases in the beta 2 wave were particularly remarkable in REM sleep.

Alteration of cataleptic responses induced by dopamine receptor antagonists after chronic cocaine administration in mice

The influence of chronic treatment of mice with cocaine, an indirect dopamine receptor agonist, on the cataleptic effects of R-(+)-chloro-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepin- 7ol hydrochloride (SCH23390), a dopamine D1 receptor antagonist, or haloperidol, mainly a dopamine D2 receptor antagonist, was investigated. Mice were given cocaine (10 mg/kg s.c.) once every other day for 7 (4 injections), 15 (8 injections) or 21 (11 injections) days. The cataleptic effects of SCH23390 (0.3 mg/kg i.p.) were significantly reduced when it was given 1-7 days after the last dose of a 7- or 15-day pretreatment course of cocaine. When SCH23390 was given 14-21 days after the cocaine the cataleptic effect was increased in the 15-day, but not the 7-day, cocaine-pretreated mice. However, after a 21-day treatment with cocaine, a challenge dose of SCH 23390 given 1-3 days thereafter produced a decreased cataleptic response, but an increased response after 7-21 days. The cataleptic effects of haloperidol (o.3 mg/kg i.p.) were reduced when it was given 1-7 days after the last dose of a 7-day pretreatment, but increased 1-3 days after that of a 15-day pretreatment with cocaine (10 mg/kg s.c.) The pretreatment with cocaine for 21 days did not affect the haloperidol catalepsy during a 1- to 3-day withdrawal period. However, haloperidol catalepsy was decreased only 7 days, then reversed 14 days and gradually increased 21 days after the last injection of a 15- or 21-day pretreatment course of cocaine. These results suggest that chronic treatment with the indirect dopamine receptor agonist, cocaine, caused supersensitivity of dopamine D1 receptors (a decrease in SCH23390 catalepsy) during the early withdrawal period and subsensitivity (an increase in SCH23390 catalepsy) after a longer period of withdrawal. It was apparent that the longer the period and the higher the dose of pretreatment with cocaine, the less were the alterations in initial responses and the greater were the alterations in subsequent responses to the dopamine D1 receptor antagonists.

Stimulatory effect of butoctamide hydrogen succinate on REM sleep in normal humans

1. The efficacy of butoctamide hydrogen succinate (BAHS) was compared with that of nitrazepam on the basis of the polysomnograms and the subjective assessments. 2. Twelve healthy male students were divided into three groups consisting of 4 subjects each with were administered BAHS 600 mg, nitrazepam 5 mg, and BAHS 600 mg + nitrazepam 5 mg, respectively. 3. Polygraphic recordings were made for 8 consecutive nights for each subject, and the polysomnograms were evaluated by computerized automatic analysis using the interval histogram method. 4. An inert placebo was administered on the first 3 nights and on the seventh and eighth nights, and the test article regimen was administered on the fourth, fifth and sixth nights. 5. The test articles and the placebo were administered orally at 22:30 hr, and the recording of polysomnograms was started at 23:00 hr and ended at 8:00 hr the next morning. 6. The subjects were requested to fill out the subjective assessment of sleep before falling asleep and after arising the next morning. 7. BAHS increased REM sleep and decreased stage 2 sleep significantly; however, it failed to affect stage 1, 3 or 4 sleep. 8. Nitrazepam increased significantly the total sleep time and stage 2 sleep but decreased significantly the stage 3 sleep and decreased slightly the stages 1, 4 and REM sleep. 9. The combined treatment with BAHS and nitrazepam did not alter the sleep parameters except for increasing the total sleep time. 10. No obvious changes were observed in the subjective assessments after administration of the drugs. 11. These findings suggest that BAHS results in a unique sleep pattern different from benzodiazepines, and that BAHS may be suitable for treating insomnia in elderly patients and those with drug abuse, manic-depressive illness or schizophrenia.

Development of tolerance and reverse tolerance to haloperidol- and SCH23390-induced cataleptic effects during withdrawal periods after long-term treatment

The development of tolerance and reverse tolerance and reverse tolerance to the cataleptic effects of selective D1 antagonist, SCH23390, and the mainly D2 antagonist, haloperidol, was investigated in mice that had been chronically treated (7 or 30 days) with haloperidol (1 mg/kg SC), SCH23390 (0.5 mg/kg SC), or saline (5 ml/kg SC). In control animals, SCH23390 (0.1-1.0 mg/kg IP) and haloperidol (0.1-1.0 mg/kg IP) produced cataleptic responses in a dose-dependent manner, although the responses had different time course profiles. SCH23390 catalepsy had a rapid onset but a short duration, whereas haloperidol catalepsy had a slower onset and longer duration. This could be due to differences in lipid solubility of the drugs, or at least pertly to an action of the drugs on different neuronal pathways. The cataleptic effects of SCH23390 (0.3 mg/kg IP) and haloperidol (0.3 mg/kg IP) were significantly reduced in mice when given 24 h, but not 72 h, after the last dose of a 7 day-pretreatment course (short-term treatment) of SCH23390. However, after long-term treatment (30 days) with SCH23390, a challenge dose of SCH23390 exhibited reverse tolerance (i.e., increased catalepsy) when given 7-21 days, but not 1-3 days, after the last injection of the SCH23390 pretreatment course. In contrast, haloperidol catalepsy was not affected by long-term SCH23390 treatment. However, after the last dose of long-term haloperidol treatment both SCH23390 and haloperidol exhibited tolerance to their cataleptic effects at 1-3 days, a normal response at 7 days, and an exaggerated response (reverse tolerance) at 15-21 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Characteristics of the anxiolytic effects of buspirone in high- and low-anxious normal humans assessed by frontal midline theta activity

Fmtheta is a distinct theta activity in the frontal midline area that appears during performance of mental tasks. It is suggested that relief from anxiety might be reflected in the appearance of Fmtheta. In the present study, the anxiolytic effects of buspirone were investigated using 24 male university students with (Fmtheta group, n = 12) and without (non-Fmtheta group, n = 12) Fmtheta. The subjects were given placebo, buspirone 5 mg and 15 mg in a double-blind, crossover design. Blood samples were obtained, scores were made on the State Trait Anxiety Inventory (STAI), and EEGs were recorded before and during performance of an arithmetic addition. The test was repeated twice: before and 1 h after drug administration. In the Fmtheta group, buspirone dose-dependently produced a decrease in plasma 5-HT and 5-HIAA concentrations and in state anxiety scores and an increase in Fmtheta amounts. In the non-Fmtheta group, however, there were no differences in these items except for 5-HT concentration before and after buspirone administration. These results suggest that anxiety in the Fmtheta group is mainly correlated with 5-HT1A receptor function, and that buspirone may have anxiolytic effects in patients with reactive anxiety but not those with endogenous anxiety.

[Effects of dopamine receptor agonists and antagonists on cocaine-induced behaviors in rats]

In this study, cocaine (5-20 mg/kg), an indirect dopamine agonist, increased locomotor activity and rearing accompanied with head circling and body shaking in a dose-dependent manner. A high dose of cocaine (40 mg/kg), meaning a toxic dose, slightly induced sniffing and licking. Both SCH23390, a D-1 receptor antagonist, and raclopride, a D-2 antagonist, inhibited all behaviors induced by cocaine, suggesting that the behavioral actions of cocaine may involve the activation of D-1 and D-2 receptors. Selective D-2 agonist quinpirole (0.1 and 1.0 mg/kg) inhibited hyperlocomotion induced by cocaine (20 mg/kg), but was replaced by the typical stereotyped behaviors such as sniffing at low dose (0.1 mg/kg), and licking and gnawing at high dose (1.0 mg/kg). SK & F38393, a selective D-1 agonist, in combination of cocaine did not induce these stereotyped behaviors which resulted in synergistic interaction of D-1 and D-2 receptor stimulation. These results suggest that the indirect stimulation of postsynaptic D-2 receptors by cocaine (20 mg/kg) was insufficient to induce stereotyped behaviors. The actions of cocaine on dopamine D-1 receptors seem to be more potent than that on D-2 receptors.

Comparative pharmacokinetics of the histamine H1-receptor antagonist ebastine and its active metabolite carebastine in rats, guinea pigs, dogs and monkeys

The pharmacokinetics of ebastine (CAS 90729-43-4), a new histamine H1-receptor antagonist, was investigated in rats, guinea pigs, dogs and monkeys. Plasma levels of ebastine and its active carboxylated metabolite, carebastine (CAS 90729-42-3), were determined after an intravenous dose (2 mg/kg) or an oral dose (10 mg/kg). After intravenous administration to dogs, plasma levels of the unchanged ebastine showed a bi-phasic decrease with a t1/2 alpha of 0.16 h and t1/2 beta of 4.2 h. In contrast, after oral administration, the unchanged ebastine was scarcely detected in plasma of 4 animal species examined, indicating extensive first-pass metabolism of ebastine. There were marked interspecies differences in the plasma concentration-time profiles of carebastine after oral administration of ebastine. The Cmax of carebastine in guinea pigs (2820 ng/ml) was markedly higher than that in rats (311 ng/ml), dogs (465 ng/ml) and monkeys (1036 ng/ml). Guinea pig also showed the slower elimination of carebastine (t1/2 of 9.4 h) than rat (0.92 h), dog (2.4 h) and monkey (1.2 h). After oral administration of carebastine to rats, the Cmax and AUC were approximately 3/4 of those after administration of ebastine. Once daily 7-day repeated oral administrations of ebastine did not affect the pharmacokinetics of ebastine and carebastine in rats. These findings strongly indicate that carebastine is responsible for the antihistamine activity after oral administration of ebastine.

Pharmacokinetics of the gastrokinetic agent mosapride citrate after intravenous and oral administrations in dogs and monkeys

The pharmacokinetics and bioavailability of mosapride citrate ((+-)-4-amino-5-chloro-2-ethoxy-N-[[4-(4- fluorobenzyl)-2-morpholinyl]methyl]benzamide citrate dihydrate, AS-4370, CAS 112885-42-4), a new gastrokinetic agent, were investigated in dogs and monkeys. Plasma levels of mosapride and its des-4-fluorobenzyl metabolite (M-1) were determined after a single intravenous dose (2 mg/kg) or a single oral dose (10 mg/kg). After intravenous administration, mean plasma levels of mosapride in male dogs and monkeys showed biphasic decrease with t1/2 alpha of 0.3 and 0.6 h, and t1/2 beta of 2.4 and 2.4 h, respectively. Mean concentrations of mosapride increased rapidly and reached the maximum 0.5-1 h after oral administration to male dogs and monkeys, followed by quick decrease with t1/2 of 1.5 and 0.9 h, respectively. The Cmax was 207 ng/ml in dogs and 862 ng/ml in monkeys. The Cmaxs of M-1 in both species were virtually equivalent to those of the unchanged drug. Plasma concentration-time profiles and pharmacokinetic parameters of mosapride and M-1 in female dogs and monkeys were similar to those in males, indicating no sex-related differences in the pharmacokinetics of mosapride in these animal species. Oral bioavailability was 8% of the dose in dogs and 14% in monkeys, suggesting the extensive first-pass metabolism of mosapride.

Pharmacokinetics of the gastrokinetic agent mosapride citrate after intravenous and oral administrations in rats

The pharmacokinetics and bioavailability of mosapride citrate ((+/-)-4-amino-5-chloro-2-ethoxy-N-[[4-(4-fluorobenzyl)-2- morpholinyl]methyl]benzamide citrate dihydrate, AS-4370, CAS 112885-42-4) were investigated in rats of both sexes. Plasma levels of mosapride and its des-4-fluorobenzyl metabolite (M-1) were determined after an intravenous dose of 2 mg/kg or an oral dose of 10 mg/kg. There were marked sex-related differences in the mean plasma concentration-time profiles of mosapride after single intravenous and oral administration. After oral administration, the Cmax of the unchanged mosapride in male rats (44 ng/ml) was approximately 1/18 of that in female rats (788 ng/ml). The Cmax of M-1 (277 ng/ml) was 6 times higher than that of mosapride in males, while the Cmax in females (149 ng/ml) was 1/5 of that of mosapride. Male rats exhibited more rapid elimination (t1/2 of 1.9 h) than females (2.8 h). These sex-dependent pharmacokinetics of mosapride in rats would be explained by two reasons: different activity of hepatic drug-metabolizing enzymes to M-1 and partly different distribution volume of mosapride. Oral bioavailability of mosapride was 7% of the dose in males and 47% in females, suggesting extensive first-pass metabolism in males. Once daily 7-day multiple administration did not affect the pharmacokinetics of mosapride both in male and female rats.

Memory and cognitive impairments in a case of long-term trihexyphenidyl abuse

We present a case of long-term trihexyphenidyl (THP) abuse in which memory and cognitive impairments were observed 23 years after the commencement of medication. This case showed a dramatic improvement after withdrawal of THP. Clinical course during admission was followed with psychometric testing and laboratory examinations. The fact that the patient showed no evidence of lowered alertness during the clinical course raises the possibility that THP can primarily induce impairment of memory and cognitive functions. This is supported by the findings on the resting EEG of the patient. This case emphasizes the need to exercise caution in prescribing high doses of anticholinergic agents for long periods, particularly in elderly patients with underlying brain pathology.

Behavioral effects of dilazep on cholinergic, dopaminergic, and purinergic systems in the rat

This study examined the effects of 1,4-bis[3-(3,4,5-trimethoxy benzoyloxy)-propyl] perhydro-1,4-diazepine (dilazep; Comelian) on central dopaminergic, cholinergic, and purinergic neuronal systems in rats. Intraperitoneal injections of dilazep (1-5 mg/kg) produced yawning responses, the most effective dose being 2 mg/kg. Dilazep potentiated physostigmine-induced yawning but not pilocarpine- and bromocriptine-induced yawning. Dilazep-induced yawning was not affected by low doses of haloperidol or sulpiride, but was completely inhibited by atropine, a muscarinic M1 receptor antagonist. Dilazep-induced yawning, as well as physostigmine-induced yawning, were markedly inhibited by pretreatment with SK & F 38393, a dopamine D1 receptor agonist, and were potentiated by SCH23390, a dopamine D1 receptor antagonist that alone does not elicit yawning. Caffeine, an adenosine receptor antagonist, inhibited dilazep- and physostigmine-induced yawning responses but N6-cyclohexyl adenosine (CHA) and N6-(L-phenylisopropyl, adenosine (L-PIA), adenosine A1 receptor agonists, were inactive. These results suggest that because the effects of dilazep on central cholinergic neurons are similar to those of physostigmine dilazep may potentiate indirectly the action of endogenous acetylcholine. Cholinergic neurons activated by dilazep may be modulated by postsynaptic dopamine D1 receptor activity but may not be affected by dopamine D2 receptor activity. Furthermore, the stimulatory effects of dilazep on cholinergic neuron may not be due to an inhibition of dopamine D1 receptors via purinergic (adenosine A1 receptor) stimulation by dilazep.

Effects of mianserin in chronic schizophrenia

1. The efficacy of mianserin as a supplement in treating chronic schizophrenia was tested by monitoring the BPRS and plasma monoamine metabolites. 2. Twenty inpatients with schizophrenia were administered fixed doses of neuroleptics throughout the study. 3. A control BPRS scoring and blood sampling were done before mianserin administration. 4. Fixed doses of 60 mg/day of mianserin for 2 weeks and flexible doses for 4 weeks were given orally in an open study for 6 consecutive weeks, and no treatment followed for 1 additional week. 5. BPRS scoring was carried out once weekly, and blood samples were obtained after mianserin treatment. 6. Both total BPRS scores and scores for negative symptoms were decreased by mianserin treatment as compared with the control values. 7. 5-HIAA concentrations of both responding patients and nonresponding patients to mianserin were increased after medication; however, 5-HIAA values of responding patients were lower than those of nonresponding patients. 8. HVA concentrations of the responding group were slightly increased by mianserin administration. 9. There were no significant changes in MHPG levels between the two groups. 10. These results suggest that the negative symptoms of schizophrenia are partly improved by mianserin treatment.

Effects of lithium and purinergic compounds on the behavioral and physiological aspects of restraint stress in rats

This study investigates the effects of lithium and caffeine on psychomotor activities, defecation, and gastric lesions induced by restraint stress. Rats exposed to restraint stress typically exhibited a biphasic response consisting of an initial hypermotility (such as tail-flipping, body-rolling, jaw movement, and vocalization) accompanied by defecation, and followed by hypomotility (decrease in motility) accompanied by gastric ulceration. Lithium chloride (150 micrograms, ICV; 50 and 100 mg/kg, IP) significantly attenuated these responses while N6-cyclohexyl adenosine (CHA; 1.5 micrograms, ICV; 0.3 mg/kg, IP), a potent adenosine A1 receptor agonist, attenuated the behavioral effects but potentiated the gastric ulceration. Caffeine (3 micrograms, ICV; 1.0 mg/kg, IP), an adenosine receptor antagonist, inhibited the effects of CHA in animals exposed to 3 h of stress, but aggravated the effects in animals exposed to 6-12 h of stress. These results suggest that caffeine consumption may produce supersensitivity of adenosine receptors, which potentiate the actions of adenosine or CHA. Lithium may modulate the effects of stress by indirectly inhibiting central adenosine receptor activity.

[The threshold lowering effects of chronic treatment with haloperidol on beta-carboline derivative-induced tonic convulsion]

To clarify a relationship between dopamine neuron and purine, GABA or benzodiazepine system, we have studied the changes in the threshold of tonic convulsion induced by each antagonist after chronic treatment with haloperidol in mice. Mice were given haloperidol (1 mg/kg, sc) once a day for 19 d and challenged with caffeine (an adenosine receptor antagonist), beta-DMCM (beta-carboline derivative: as a benzodiazepine receptor antagonist), picrotoxin (a Cl- channel blocker) or bicuculline (a GABAa receptor antagonist) 30 min, 24 h and 48 h after the last injection of haloperidol. Only the threshold of beta-DMCM-induced tonic convulsion was lowered and it was reversed 7 d after the last injection. The beta-DMCM-induced convulsions on 2 d withdrawal were reversed by diazepam (2.5 mg/kg, ip; a benzodiazepine receptor agonist), Ro15-1788 (5.0 mg/kg, ip; as like a benzodiazepine receptor partial agonist), muscimol (2.0 mg/kg, ip; a GABAa receptor agonist) or apomorphine (0.25 and 2.0 mg/kg, ip; a dopamine receptor agonist). These results suggest that the lowering effect of chronic haloperidol on seizure threshold may be involved in the development of tolerance to haloperidol. It may implicate in direct interactions between benzodiazepine and dopamine or GABA systems but may not between dopamine and GABA neurons in development of lowering seizure threshold following chronic haloperidol treatment.

Differential responses to mental stress in high and low anxious normal humans assessed by frontal midline theta activity

The distinct EEG theta rhythm from the frontal midline area observed during performance of mental tasks has been called Fm theta. In the present study, plasma catecholamine responses to mental stress were investigated using male students with (n = 12) and without (n = 12) Fm theta. The subjects were requested to complete the trait anxiety scale of STAI, and control blood samples were obtained. 65 min later, their EEGs were recorded during performance of an arithmetic addition task for 5 min. The state anxiety scores of STAI were obtained twice before and after the EEG recording. Blood samples were drawn three times during the state anxiety test and the EEG recording. The Fm theta appearance group showed low trait anxiety and a decrease of state anxiety after the mental task; however, the Fm theta non-appearance group exhibited high trait anxiety and no changes of state anxiety before and after the mental task. The concentrations of DA, HVA, NA and MHPG in the Fm theta appearance group showed lower levels at all times compared to those in the non-appearance group. In the Fm theta appearance group, an increase of DA turnover was observed by the addition of mental task. On the other hand, the Fm theta non-appearance group showed an increase of NA turnover.

Psychological stress increases dopamine turnover selectively in mesoprefrontal dopamine neurons of rats: reversal by diazepam

The effects of psychological stress on catecholamine and indoleamine metabolism were examined in various brain regions of rats. Psychologically stressed rats were exposed to emotional responses of foot-shocked rats, but were themselves prevented from receiving foot-shock. Psychological stress for 30 min resulted in significant increases of both 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) levels in the medial prefrontal cortex (MPFC), but not in other dopamine (DA) terminal fields. The levels of noradrenaline (NA), serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) were unaffected in all brain regions examined after 30 min of psychological stress. A small but significant increase of DOPAC levels in the ventral tegmental area (VTA) was observed after a shorter (10 min) duration of stress. Moreover, an increase of DOPAC levels in the MPFC 30 min after psychological stress was attenuated by diazepam (5 mg/kg), and this attenuating effect was antagonized by Ro 15-1788 (15 mg/kg). These results suggest that mesoprefrontal DA neurons are selectively activated by psychological stress, and that the activation of the A10 cell body site (VTA) may precede that of the terminal field (MPFC). Moreover, diazepam was found to possess an inhibitory effect on the activation of mesoprefrontal DA neurons induced by psychological stress, and this effect may be partly mediated by benzodiazepine (BZD) receptors and implicated in the specific anxiolytic action of BZDs.

Effects of indeloxazine hydrochloride on sleep in normal humans

The effects of 40 mg of indeloxazine hydrochloride, a cerebral metabolic enhancer, on sleep were investigated in 6 healthy male students. Polygraphic recordings were made for 8 consecutive nights on each subject. An inert placebo was given on the first 3 nights and on the 7th and 8th nights, and 40 mg of indeloxazine was administered on the 4th, 5th and 6th nights. Drug and placebo were administered orally at 21:30 h, and the recording of polysomnograms started at 22:00 h and ended at 8:00 h the next morning. The polysomnograms were evaluated by computerized automatic analysis using the interval histogram method. Indeloxazine prolonged both sleep latency and REM latency, and increased stage 1 sleep, but decreased stages 3, 4 and REM sleep. A significant increase of REM sleep was observed on the 7th and 8th recovery nights. No obvious changes were shown in the subjective assessments after administration of the drug. These results suggest that the effects of indeloxazine on sleep are similar to those of the tricyclic antidepressants. Furthermore, polysomnographic examinations might be useful in evaluating the pharmacological properties of cerebral metabolic enhancers.

Effects of mianserin on negative symptoms in schizophrenia

The efficacy of mianserin as a supplement in treating chronic schizophrenia was tested in 20 inpatients with schizophrenia who were receiving fixed doses of neuroleptics. Mianserin was given for six weeks with a starting dose of 60 mg/day. A brief psychiatric rating scale (BPRS) was completed before starting mianserin and thereafter BPRS scoring was carried out once weekly. The total BPRS score and the score for negative symptoms were decreased by mianserin treatment as compared to the pre-treatment values. Plasma 5-HIAA concentrations were increased after medication in both responding patients and nonresponding patients. However, the 5-HIAA values of responders were lower than those of nonresponders. Plasma HVA levels were slightly increased by mianserin in the responders. There were no significant changes in MHPG levels. These results suggest that the negative symptoms of schizophrenia may be improved by mianserin treatment.

A physiological marker for assessing anxiety level in humans: frontal midline theta activity

The distinct theta rhythm in the frontal midline area during performance of mental tasks has been designated as Fm theta. Sixteen male university students who failed to show any appearance of Fm theta in 3 consecutive days were given diazepam 5 mg, amobarbital 80 mg, methylphenidate 15 mg and placebo, in a double-blind, crossover design. Scores were made on the state anxiety scale of STAI; EEGs were recorded before and during performance of an arithmetic addition. The test was repeated twice: before and one hr after drug administration. Fm theta appeared following the drug administration even in those who had never shown the appearance of Fm theta, and the appearance time of Fm theta increased in the following order: diazepam greater than amobarbital greater than placebo greater than methylphenidate. The scores of STAI decreased in the same order. The speed of performed tasks was increased by methylphenidate and placebo, but decreased by amobarbital and diazepam. These results suggest that relief from anxiety might be reflected in the appearance of Fm theta and that Fm theta might be a useful tool to measure the anxiety level in humans.

Interaction of enoxacin with theophylline in rats

Enoxacin (ENX) has been reported to raise significantly plasma levels of theophylline (TP) in humans. In order to elucidate a mechanism of this interaction, in vivo and in vitro studies were carried out in rats. Concomitant dosing of ENX with TP significantly elongated plasma elimination half-life of TP, which led to a marked increase in the maximum plasma TP level after repeated administrations of both drugs. In rats treated with ENX, urinary excretion of unchanged TP increased and that of TP metabolites comparably decreased. The pharmacokinetic analysis showed that ENX did not change renal clearance of TP and these observed effects of ENX were attributed to reduced metabolic clearance of TP. In the in vitro studies by using liver microsomes, ENX reduced the magnitude of the type II difference spectral interaction of TP with cytochrome P-448 (P-448) and the formation of TP metabolites catalyzed by P-448. These results strongly suggest that the inhibition of the TP binding to the ferric iron of P-448 leads to that of the TP metabolism. The most essential site of ENX to inhibit the TP metabolism was found to be the 4'-nitrogen atom in the 7-piperazinyl group, and the stereochemical structure of ENX was suggested to be responsible for this inhibition.

Effects of dilazep (Comelian) on the central purinergic system: inhibitory effects on clonidine-induced aggressive behavior

Mice given clonidine (20-50 mg/kg i.p. and 5 micrograms i.c.v.) exhibited aggressive behavior. Dilazep as well as N6-(L-phenylisopropyl) adenosine (adenosine agonist) inhibited this behavior. Dilazep combined with N6-(L-phenylisopropyl) adenosine markedly inhibited the behavior at low doses that were without effect when given alone whereas the inhibitory effect of dilazep on the behavior was reversed by caffeine and 8-phenyltheophylline, which are adenosine antagonists. The results suggest that the inhibitory action of dilazep on clonidine-induced aggressive behavior can be substantially attributed to central purinoceptor stimulation.

[Effects of bifemelane on central dopaminergic and cholinergic systems in rats]

The study served to examine the effects of bifemelane on central dopaminergic-cholinergic neuronal mechanisms in rats. Bifemelane (5-20 mg/kg) evoked yawning responses, the frequency being low. Bifemelane (10 mg/kg) as well as bromocriptine (2.5 mg/kg) potentiated physostigmine (0.2 mg/kg)-, bromocriptine (2.5 mg/kg)- or apomorphine (0.1 and 0.5 mg/kg)-induced yawning but completely inhibited pilocarpine-induced yawning. Pretreatment with sulpiride (20 mg/kg) and a low dose of haloperidol (0.02 mg/kg) reversed the stimulatory effect of bifemelane on physostigmine-induced yawning and the inhibitory effect of the drug on pilocarpine-induced yawning, whereas atropine (5 mg/kg) diminished these yawning responses. SK&38393 (2.0 mg/kg), a dopamine D-1 receptor agonist, markedly potentiated bifemelane- and bromocriptine-induced yawning but inhibited physostigmine-induced yawning, and did not affect pilocarpine-induced yawning. The increased yawning responses were blocked by atropine and a low dose of haloperidol. Bifemelane (10 mg/kg) and bromocriptine (2.5 mg/kg) tended to increase apomorphine (5 mg/kg)-induced oral stereotypy, such as licking and biting, but the increase was not significant. These results suggest that the effects of bifemelane on central dopaminergic and cholinergic neurons may be similar to those of bromocriptine.

Automatic real-time analysis of human sleep stages by an interval histogram method

A new interval histogram method for automatic, all-night sleep stage scoring, simulated on a digital computer, is described. The system consists of a 2-step analysis. The first step is recognition of elementary patterns in EEG, EOG and EMG, and the second step is the determination of sleep stages based on these parameters. Correlation of this method with power spectral analysis of the dominant EEG patterns during each sleep stage supported the reliability of the first step analysis. Overall agreement (89.1%) between the computer and human judges was only 3% less than the agreement (92.1%) among the scorers, indicating considerable reliability of the second step. The primary areas of disagreement that arose in the identification of sleep stages occurred with stages 1, 2 and REM. To improve scoring accuracy, the system may require epoch sequence information. The profile of the elementary parameters of the EEG signals clearly illustrated the cyclic nature of these activities throughout the night. The alpha and delta 2 waves clearly separated the awake state from sleep stages. Beta 2 can discriminate stages 1 and REM from stage 2, and the best indicator for distincting stage 1 from REM was muscle activity. Sigma and spindles were prominent during stage 2 sleep. Both delta 2 and high voltage delta waves distinguished stage 3 from stage 4. On the other hand, delta 1 was evenly distributed and seemed to be common to all sleep stages.

Benzodiazepines increase tonic component of postdecapitation convulsions in mice

The effects of benzodiazepines (BDZs) and GABA system on tonic and clonic component of postdecapitation convulsion (PDC) were studied in mice. Mice decapitated at the occipito-cervical junction, exerted biphasic convulsions, i.e., initially tonic and subsequently clonic convulsions. BDZs such as diazepam or clonazepam increased tonic and clonic components of PDC. These effects were not antagonized by Ro 15-1788, a benzodiazepine receptor antagonist. The increased tonic component was antagonized by the GABA receptor antagonists, bicuculline and picrotoxin, whereas the clonic component was augmented by them. Aminooxyacetic acid, which increases the endogenous GABA content by inhibiting the GABA-transaminase, increased the tonic component significantly; this increase was antagonized by both bicuculline and picrotoxin. Muscimol, a GABA agonist, however did not affect the tonic components but rather augmented the clonic component. Bicuculline and picrotoxin did not antagonize this effect of muscimol. These results indicate that endogenous GABA may play a crucial role in mediating the tonic component of PDC and the facilitation of this component by BDZs may also be due to the activation of GABA in the spinal cord. Furthermore, the mechanisms of the tonic component may be different from that of the clonic component.

Effects of Neurotropin on polysomnographic patterns in normal humans

The effects of Neurotropin, an analgesic drug, on polysomnographic patterns were investigated in 6 male healthy volunteers aged from 18 to 23 years (mean age 21.1 years). Polysomnographic recordings were made for 6 consecutive nights from each subject. An inert placebo, identical to the Neurotropin tablets, was given on the first 3 nights and on the sixth night. Forty-eight mg of Neurotropin (4 tablets containing 12 mg of Neurotropin each) was administered on the fourth and fifth nights. The drug and placebo were administered orally 30 min before starting the record of polysomnograms, i.e. around 22.00 h and continued until the natural awakening of the subjects the next morning. The polysomnographic record of the first night was discarded from the data, because of the first night effect. Neurotropin, given on the fourth night, significantly reduced total sleep time, stage 3 and percent of stage 3 as compared to those of the baseline placebo nights. Neurotropin given on the fifth night significantly decreased only total awakening time. These effects were not observed on the sixth placebo night (recovery night). As for the subjective assessments, no obvious changes were observed after administration of the drug. These results suggest that Neurotropin decreases total sleep time as well as stage 3 sleep. However, these effects are transient and unaccompanied by rebound phenomena. It is further suggested that Neurotropin seems to elevate slightly and transiently the arousal level.

Effects of ethyl loflazepate (CM 6912) on sleep in normal humans

The effects of 2 mg and 4 mg of ethyl loflazepate (CM 6912), a new anxiolytic benzodiazepine, on sleep were studied in 12 healthy male subjects. Polygraphic recordings were made for 6 consecutive nights from each subject. An inert placebo was given on the first 3 nights and on the sixth night, and 2 mg or 4 mg of CM 6912 was administered on the fourth and fifth nights to 6 subjects, respectively. The drug and placebo were administered orally 30 min after supper, and the record of polysomnograms started at 22:30 hr and continued until the natural awakening of the subjects the next morning. The polysomnograms were evaluated by computerized automatic analysis using the method of interval histogram. Both doses of CM 6912 increased total sleep time, and reduced sleep latency and total awakening in a dose-dependent manner. Both doses slightly decreased stage 1 sleep, significantly increased stage 2 sleep, but slightly decreased stages 3, 4 and REM sleep. These changes continued into the sixth recovery night. No obvious changes were observed in subjective assessments after administration of CM 6912. These results suggest that CM 6912 is an efficacious compound and has minimal adverse effects on sleep.