[Dissociation of two components of rat behaviour by psychotropic drugs. Utilization for studying anxiolytic drugs]

Effects of tamoxifen and glutamate and glutamine levels in brain regions in repeated sleep deprivation-induced mania model in mice

Protein kinase C inhibitor tamoxifen reduces symptoms of acute mania in bipolar patients and mania-like behaviors in animals. Memory impairment and altered levels of glutamate and glutamate/glutamine ratio have been reported in mania. Tamoxifen suppresses glutamate release which plays an important role in memory. The present study evaluated whether tamoxifen's activity participates in its antimanic efficacy in repeated sleep deprivation mania model. Mice were divided into control and 24-h sleep-deprived groups and were treated with vehicle or 1 mg/kg tamoxifen twice daily for 8 days. Sleep deprivation was repeated three times at intervals of 2 days. Square crossing and rearing were recorded as measures of locomotor activity. Memory and risk taking behavior were evaluated using novel object recognition and staircase tests, respectively. Glutamate and glutamine levels were measured in the frontal cortex and hippocampus. Behavioral tests were conducted 24 h after the second or immediately after the third sleep deprivations. Sleep deprivation increased locomotor activity and risk taking. Glutamate and glutamine levels and glutamate/glutamine ratio in the frontal cortex and hippocampus were unaffected. Locomotor hyperactivity was prevented by tamoxifen treatment. No change in the recognition index suggested lack of memory impairment in the model. These findings confirm the relevance of repeated sleep deprivation as a mania model and tamoxifen as an antimanic agent. However, future research is needed to further address lack of memory impairment in the model and lack of glutamatergic influence on the model and antimanic effect of tamoxifen.

Evaluation of n-hexane extract of Viola betonicifolia for its neuropharmacological properties

Viola betonicifolia (whole plant) has been used as a sedative and in various nervous disorders in Pakistani traditional medicines. The n-hexane extract of the whole plant of V. betonicifolia (HEVB) was investigated for neuropharmacological properties such as anxiolytic, muscle relaxant, sleep induction, antidepressant and sedative to ascertain its folk use. Anxiolytic activity was tested using the staircase test, while the muscle relaxing property of the extract was tested in various muscle relaxant paradigms, i.e. chimney test, traction test, rota rod and inclined plane. In anxiolytic and muscle relaxant tests, HEVB (0.3, 0.4 and 0.5 g/kg, i.p.), diazepam (1 mg/kg, i.p.) or distilled water (10 ml/kg i.p.) were administered 30, 60 and 90 min before performing the tests in mice. HEVB was also screened for a sleep-inducing effect. The antidepressant activity was determined by using the forced swimming test (FST), while line crossing in a special box was used for locomotor activity. HEVB showed a significant (P < 0.05) dose-dependent anxiolytic action in the staircase test. In muscle relaxant paradigms, a dose-dependent muscle relaxation was observed. For the phenobarbitone sleep induction test, HEVB notably (P < 0.05) reduced the latency time and increased the total sleeping duration. However, HEVB was devoid of any antidepressant activity, while the movements of mice were reduced significantly (P < 0.05) in locomotor activity. The results suggest that HEVB has anxiolytic, muscle relaxant, sleep-inducing (sedative) activity and, thus, provides pharmacological justification for the use of this plant as a sedative and for the relief of various nervous disorders.

Anxiety in mice: a principal component analysis study

Two principal component analyses of anxiety were undertaken investigating two strains of mice (ABP/Le and C57BL/6ByJ) in two different experiments, both classical tests for assessing anxiety in rodents. The elevated plus-maze and staircase were used for the first experiment, and a free exploratory paradigm and light-dark discrimination were used for the second. The components in the analyses produced definitions of four fundamental behavior patterns: novelty-induced anxiety, general activity, exploratory behavior, and decision making. We also noted that the anxious phenotype was determined by both strain and experimental procedure. The relationship between behavior patterns and the use of specific tests plus links with the genetic background are discussed.

Anxiolytic-like action in mice treated with nitrous oxide and oral triazolam or diazepam

Few animal studies have explored the interaction of nitrous oxide (N2O) with a benzodiazepine (BNZ) administered by the oral route, as used in clinical procedures involving "conscious sedation". The purpose of this study was to evaluate the relative "anxiolytic-like" and sedative effectiveness of N2O, oral triazolam (TRIAZ; Halcion) or oral diazepam (DIAZ; Valium), either alone or in various combinations of drugs and doses. One hundred and twelve Swiss Webster male mice, 35-45 days old, were assigned to 28 groups, each of which contained four mice. The mouse staircase test was used for the assessment of anxiety (number of rearings) and sedation (number of steps ascended). Three doses of oral TRIAZ (0.1, 0.3, 1.0 mg/kg) or DIAZ (2.0, 3.5, 5.0 mg/kg) were given in combination with room air, or N2O/O2 at a N2O concentration of 25, 50 or 75%. Each mouse was tested once. N2O alone did not reduce NR in any concentration, but caused a significant increase in locomotion. DIAZ without N2O reduced NR only with the middle and high doses, but the addition of N2O significantly enhanced the anxiolytic-like effect of all DIAZ doses. TRIAZ, alone, reduced NR only in the highest dose, but added N2O resulted in anxiolytic-like behavior with all three TRIAZ doses. The sedative effects of the BNZs were extremely variable. Only the middle dose of DIAZ plus 25% N2O unequivocally reduced the number of steps ascended, i.e., caused sedation. TRIAZ lacked the inverted U-shaped dose-response relationship with NR usually seen with DIAZ. TRIAZ, therefore, provides better dose control. This behavioral animal model indicates that the optimal combinations for reduction of anxiety-like behavior with minimal effects on sedation are 0.1 mg/kg oral TRIAZ with 25% N2O or 2.0 mg/kg oral DIAZ with 25% N2O.

The pharmacology of CP-154,526, a non-peptide antagonist of the CRH1 receptor: a review

Since CRH has been shown to mediate stress-induced physiological and behavioral changes, it has been hypothesized that CRH receptor antagonists may have therapeutic potential in disorders that involve excessive CRH activity. CP-154,526 and its close analog antalarmin are potent, brain-penetrable, selective nonpeptide CRH1 receptor antagonists that were discovered in an effort to develop compounds with efficacy in CNS disorders precipitated by stress. Since its discovery many investigators have used CP-154,526 as a tool to study the pharmacology of CRH and its receptors and to evaluate its therapeutic potential in a variety of CNS and peripheral disorders. Systemically-administered CP-154,526 has been demonstrated to antagonize CRH- and stress-induced neuroendocrine, neurochemical, electrophysiological, and behavioral effects. These findings support the hypothesis that CRH1 receptor antagonists may have therapeutic utility in a number of neuropsychiatric disorders. CP-154,526, as well as other CRH1 receptor antagonists that have since been discovered, have also shown activity in several preclinical models of anxiety, depression, and substance abuse, while having little effect on locomotor activity and motor function. Although these effects are on occasion inconsistent among different laboratories, clinical evaluation of CRH1 antagonists appears justified on the basis of these and clinical data implicating the involvement of CRH in several CNS disorders. The effects of CRH1 antagonists on cognition, neurodegeneration, inflammation, and the gastrointestinal system have not been as extensively characterized and additional studies will be necessary to evaluate their therapeutic potential in these areas.

Effects of nitric oxide synthase inhibitors 7-NI, L-NAME, and L-NOARG in staircase test

BACKGROUND

The objective of the study was to investigate the effects of the nitric oxide synthase (NOS) inhibitors 7-nitroindazole (7-NI), N(G)-nitro-L-arginine (L-NOARG), and N(G)-nitro-L-arginine methyl ester (L-NAME) on the behavior of mice in the staircase test.

METHODS

NOS inhibitors 7-NI (20-120 mg/kg), L-NOARG (20 and 40 mg/kg), and L-NAME (20 and 40 mg/kg) were administered intraperitoneally (i.p.) 30 min prior to the staircase test. Staircase test consisted of placing a mouse in an enclosed staircase with five steps and recording the number of rearings made and the number of steps climbed during a 3-min period.

RESULTS

7-NI and L-NOARG did not have a significant effect on the behavior of mice in the staircase test. L-NAME caused a decrease in the number of rearings without changes in the number of steps taken.

CONCLUSIONS

NOS inhibitor L-NAME but not 7-NI or L-NAME induced an anxiolytic effect in the staircase test.

Small platform stress increases exploratory activity of mice in staircase test

Small platform (SP) stress was induced by placing mice on small platforms (3.5 cm diameter) surrounded by water for 24 h. This model contains several factors of stress like rapid eye movement (REM) sleep deprivation, isolation, immobilization and falling into the water. The staircase test consisted of placing a mouse in an enclosed staircase with 5 steps and recording (1) the number of steps and (2) rearings made during 3 min. SP stress increased the exploratory activity of mice in the staircase test as evidenced by an increase in the number of steps and rearings made In control mice diazepam (0.25 and 0.5 mg/kg) induced an anxiolytic effect in the staircase test as evidenced by a decrease in the number of rearings without changes in the number of steps. In SP stressed mice the anxiolytic effect of diazepam was not seen and the sedative effect as evidenced by a decrease in the number of steps was more pronounced. Buspirone at a dose of 1.0 mg/kg did not have effect on the behaviour of control or SP stressed mice in the staircase test. To study possible diurnal variations the staircase test was carried out at 3 different times of a day (08:00, 14:00, 20:00) with control and SP stressed mice. The exploratory activity of control mice in the staircase test gradually increased from 08:00 to 20:00 as evidenced by an increased number of steps and rearings made. SP stress increased the exploratory activity of mice irrespective of the time of testing. In conclusion, on the basis of these data the authors can propose that SP stress increases the exploratory activity of mice in the staircase test and induces a hyposensitivity of mice to the anxiolytic effect of diazepam. The effect of SP stress on the behaviour of mice in the staircase test is not caused by the disruptance of diurnal rhythms.

The effects of flumazenil, Ro 154513 and beta-CCM on the behaviour of control and stressed mice in the staircase test

The effects of flumazenil, Ro 154513 and beta-CCM in the staircase test were studied in control and small platform (SP) stressed mice. SP stress was induced by placing mice on small platforms (3.5 cm in diameter) surrounded by water for 24 h. This model contains several factors of stress, such as rapid eye movement sleep deprivation, isolation, immobilization and falling into the water. The staircase test consisted of placing a mouse in an enclosed staircase with five steps and recording: (i) the number of rearings and (ii) steps made during 3 min. SP stress increased the exploratory activity of mice in the staircase test as demonstrated by an increase in the number of rearings and steps made. In control mice flumazenil (2.0 and 10.0 mg/kg), Ro 15-4513 (1.0 and 3.0 mg/kg) and beta-CCM (1.0 and 2.0 mg/kg) exerted an anxiogenic effect that was demonstrated by an increase in the number of rearings without significant changes in the number of steps. Similar to control mice, flumazenil induced an anxiogenic effect in SP stressed mice as demonstrated by an increase in the number of rearings. However, the sedative effect of flumazenil as demonstrated by a decrease in the number of steps made was more pronounced in SP stressed mice. In the SP stressed mice, the anxiogenic effect of Ro 15-4513 and beta-CCM was masked by their strong sedative effect and a decrease in both measures of exploratory activity (number of rearings and number of steps). These data suggest that SP stress induces hypersensitivity to the sedative effect of flumazenil, Ro 15-4513 and beta-CCM in the staircase test.

Differences in anxiety-related behavior and response to diazepam in BALB/cByJ and C57BL/6J strains of mice

The study in an ethological perspective of inbred strains of mice offers a more accurate description of anxiety-related behavior. In this context, behavioral performances of the BALB/cByJ and C57BL/6J strains were systematically compared in the staircase test, the light/dark test and the elevated plus maze test. A rarely used variable, the latency of the first entry in the dark box, was also recorded in the light/dark test. A new statistical approach to this measure meant that specific avoidance strategies could be differentiated in the two strains. A study of the behavioral responses of the two strains given treatment with diazepam, a widely used anxiolytic compound, was also carried out. Results showed substantial differences between BALB/cByJ and C57BL/6J strains. C57BL/6J mice had high baseline activity and exploration of a new environment, suggesting a low level of anxiety. BALB/cByJ mice displayed defensive and protective behavior, with limited exploration of the new environment together with low locomotor activity. The response to diazepam was also different for each strain: C57BL/6J mice showed higher sensitivity to diazepam treatment than did BALB/cByJ mice.

Cerebellar GABA(A) receptors and anxiolytic action of diazepam

Alcohol-sensitive ANT rats have a point mutation in the cerebellum-enriched GABA(A) receptor alpha6 subunit, which makes this subunit and the ANT rats in vivo highly sensitive to benzodiazepine agonists. In the elevated plus maze test of anxiety, diazepam produced a greater anxiolytic response in the ANT rats than in the control, alcohol-insensitive AT rats. The ANT rats were less sensitive to the sedative effect of diazepam in the staircase test of exploration. The results thus suggest that the mutant cerebellar granule cell layer receptors can participate in GABA(A) receptor-activation-induced anxiolysis.

Brain-derived neurotrophic factor transgenic mice exhibit passive avoidance deficits, increased seizure severity and in vitro hyperexcitability in the hippocampus and entorhinal cortex

Transgenic mice overexpressing brain-derived neurotrophic factor from the beta-actin promoter were tested for behavioral, gross anatomical and physiological abnormalities. Brain-derived neurotrophic factor messenger RNA overexpression was widespread throughout brain. Overexpression declined with age, such that levels of overexpression decreased sharply by nine months. Brain-derived neurotrophic factor transgenic mice had no gross deformities or behavioral abnormalities. However, they showed a significant passive avoidance deficit. This deficit was dependent on continued overexpression, and resolved with age as brain-derived neurotrophic factor transcripts decreased. In addition, the brain-derived neurotrophic factor transgenic mice showed increased seizure severity in response to kainic acid. Hippocampal slices from brain-derived neurotrophic factor transgenic mice showed hyperexcitability in area CA3 and entorhinal cortex, but not in dentate gyrus. Finally, area CA1 long-term potentiation was disrupted, indicating abnormal plasticity. Our data suggest that overexpression of brain-derived neurotrophic factor in the brain can interfere with normal brain function by causing learning impairments and increased excitability. The results also support the hypothesis that excess brain-derived neurotrophic factor could be pro-convulsant in the limbic system.

Nitrous oxide anxiolytic effect in mice in the elevated plus maze: mediation by benzodiazepine receptors

In earlier research, we have hypothesized that exposure to nitrous oxide (N2O) produces an anxiolytic effect that is mediated by benzodiazepine (BZ) receptors. The present research was conducted to characterize pharmacologically the behavioral effects of N2O in comparison with a BZ standard, chlordiazepoxide (CP), in the mouse elevated plus maze. Exposure to increasing levels of N2O produced a concentration-related increase in the percent of total entries into and the percent of total time spent on the open arms, a pattern of response similar to that induced by CP. These effects on N2O and CP were both antagonized by pretreatment with the BZ receptor blocker flumazenil (FLU). In another experiment, mice made tolerant to CP also exhibited a cross-tolerance to N2O. These results support the hypothesis that the anxiolytic effect of N2O is mediated by BZ receptors.

Effects of oral ethanol self-administration on the inhibition of the lever-press response in rats

The effects of ethanol on the inhibition of a learned response were examined in adult, male Wistar rats from two treatment groups: oral self-administration of alcoholic solution (10% ethanol and 10% glucose in distilled water) and oral self-administration of sweet solution (10% glucose in distilled water). Subjects were food deprived and alcoholic or control solutions were available 1 h per day during 15 days. After this period, rats were tested in a two-bottle paradigm during 1 h per day and placed in the operant chambers immediately afterward. This phase went on for 19 days. Subjects were trained to lever press for food and were tested in a continuous reinforcement schedule, operant extinction, successive discrimination, and two-stimuli tests. Alcohol impaired the ability to inhibit previously reinforced responses but only in situations indicated by exteroceptive stimuli. Ethanol intake did not impair the lever-press behavior neither in the acquisition of the response nor in the continuous reinforcement schedule. These data suggest that the sedative effects of alcohol at this dose were not apparent in reinforcement situations, in contrast with extinction situations.

Roman strains as a psychogenetic model for the study of working memory: behavioral and biochemical data

Performances of male rats of the Roman High- (RHA), Roman Control- (RCA) and Roman Low- (RLA) Avoidance strains were compared in two working memory tests, a spatial one, the radial maze, and a nonspatial one, an object recognition test. The same rats were subjected to measures of emotional reactivity and of different forms of motor activity and finally to measures of cholinergic and aminergic activities in the hippocampus, frontal cortex and striatum. Compared to RHA, RLA performed better in the two working memory tests, displayed "anxiety" and had also lower levels of exploratory locomotor activity. Hippocampal ChAT activity was higher in RLA than in RHA. Levels of DA and DOPAC in the striatum were higher in RLA compared to RHA, whereas in the frontal cortex they were lower. For most of these measures, RCA were intermediate between RLA and RHA. These results confirm and extend the finding that the Roman strains are not only a genetic model for two-way avoidance conditioning but also for working memory.

Ethologically-based animal models of anxiety disorders

An overview of ethologically-based animal models suitable for investigating the pharmacological treatment of anxiety disorders is presented. The DSM-IIIR classification provides a framework for the discussion. The limitations of the models in current use are considered. It is suggested that there is a need for a greater emphasis on animal models of anxiety with an etiological basis.

Effects of benzodiazepine agonist, inverse agonist and antagonist drugs in the mouse staircase test

This study examined the effects of the benzodiazepine agonist midazolam and inverse agonist noreleagnine independently and in conjunction with the antagonist flumazenil in the mouse staircase test. According to this paradigm, the numbers of steps ascended (NSA) and rears (NR) reflect locomotor activity and anxiety, respectively. Midazolam reduced NR at doses that did not affect NSA; this NR-lowering effect was blocked by flumazenil. Noreleagnine increased NR at doses that did not affect NSA; this NR-elevating effect was also blocked by flumazenil. Effective antagonist doses of flumazenil alone had no effect on NR or NSA. The exactly opposite effects of midazolam and noreleagnine on NR and their antagonism by flumazenil are consistent with the postulated activities of these drugs at benzodiazepine receptors.

Behavioural effects of the benzodiazepine receptor partial agonist RO 16-6028 in mice

The imidazo-diazepinone RO 16-6028 is a benzodiazepine receptor partial agonist which exhibits some anti-conflict effects in the two-chambered light/dark test without significantly affecting the behaviour of mice confronted with the staircase test. In addition, this drug slightly reduced locomotion and more markedly rearing in a free exploration procedure. These results indicate that RO 16-6028 appears to produce some anxiolytic and sedative properties like full agonists, but with weaker magnitude. This could be related to the benzodiazepine partial agonistic profile of the compound.

Does RO 15-4513 reverse the anxiolytic effects of ethanol by its intrinsic properties?

In order to better understand the antagonistic effects of the partial inverse agonist of benzodiazepine receptors, RO 15-4513, against the disinhibitory action of ethanol, we examined the effects of RO 15-4513 at a dose (2.0 mg/kg) that did not alter locomotor activity, given alone or in combination with ethanol, on the behavior of mice confronted with the light/dark choice procedure and the staircase test. At this dose, RO 15-4513 given alone was found to have slight anxiogenic properties and when given in combination with ethanol, to completely reverse the disinhibitory effects of ethanol. Since we previously observed postictal depression after higher doses of RO 15-4513 given alone and antagonistic effects of these same doses on the action of ethanol, it can be suggested that the antagonistic effects of RO 15-4513 against ethanol are due to its anxiogenic or depressive properties depending on doses. However, this hypothesis can only be regarded as being in early stages of development at the present time since these results do not parallel with those of several other studies and the question whether the antagonistic action of RO 15-4513 against ethanol is additive or interactive remains open.

Benzodiazepine antagonist RO 15-1788 partly reverses some anxiolytic effects of ethanol in the mouse

The effects of the benzodiazepine (BZD) receptor antagonist RO 15-1788 (3 mg/kg) on the anxiolytic properties of ethanol in mice confronted with a light/dark choice procedure and with the staircase test were investigated. RO 15-1788 reversed the effects of ethanol on some of the behavioural parameters without eliciting intrinsic effects when given alone. These data closely resemble those we previously obtained with several BZD receptor inverse agonists such as RO 15-3505, RO 15-4513 or beta-CCM. Since anxiogenic-like properties of low doses of RO 15-1788 have been identified by other authors, it is suggested that the antagonistic action of this drug against some of the behavioural effects of ethanol could be due to its being a partial BZD inverse agonist.

The benzodiazepine receptor inverse agonists beta-CCM and RO 15-3505 both reverse the anxiolytic effects of ethanol in mice

The antagonistic effects of the benzodiazepine receptor inverse agonist beta-CCM (1 mg/kg) and of the partial inverse agonist RO 15-3505 (3 mg/kg) on the anxiolytic properties of ethanol (1 g/kg) in mice confronted with a light/dark choice procedure and with the staircase test were investigated. Both drugs reversed the effects of ethanol on some of the behavioral parameters, but beta-CCM alone elicited anxiogenic intrinsic effects. RO 15-3505 induced seizures in mice treated with a subconvulsant dose of pentylenetetrazole, the most efficient doses being 3 and 6 mg/kg. These data indicate that beta-CCM and RO 15-3505 can reverse some of the anxiolytic effects of ethanol, acting probably to oppose GABA function via the benzodiazepine receptor.

Rearing and step climbing behavior of X-linked hypophosphatemic (Hyp) mice

Hyp mice are a model for X-linked hypophosphatemia, the most common form of vitamin D-resistant rickets. Previous reports indicate alterations in the nervous system of these mice. The present study examined rearing and step climbing behavior in Hyp mice in the staircase test. We found that male Hyp mice have large reductions in both the number of rears and steps climbed when compared to normal male mice. When compared to normal female mice, female Hyp mice have a small reduction in the number of steps climbed but no significant reduction in the number of rears. However, they have greater rearing and climbing activity than male Hyp mice. These reductions in activity are not correlated with the severity of bone disease. Gonadectomy had no effect on activity in male mice but reduced activity comparably in both Hyp and normal female mice. We conclude that Hyp mice have altered behavior in the staircase test and that the magnitude and type of the alteration is influenced by the sex of the animal.

Comparing benzodiazepines using the staircase test in mice

Eleven benzodiazepines were evaluated in the staircase test in mice. The behavioural parameters measured were the number of steps climbed and the number of rears during a 3-min test. Climbing and to a lesser extent rears were enhanced at low doses, whereas both parameters, particularly rearing, were reduced at higher doses. The differential effects of the drugs on the two parameters were used to determine indices of anxiolytic efficacy for each drug where increases in climbing were taken to indicate the onset of anxiolytic activity and decreases in rearing the onset of sedative activity. The compounds could be ranked according to these indices in a manner which appears to reflect their therapeutic profile in man.

Comparison of nitrous oxide, morphine and diazepam effects in the mouse staircase test

Mice were exposed for 10-20 min to room air, 100% oxygen (O2) or increasing concentrations of nitrous oxide (N2O) in O2, then tested for 3 min in a staircase inside a glovebag. N2O produced a concentration-dependent increase in the number of steps ascended (NSA) but no change in the number of rears (NR). Pretreatment with naloxone reversed the increase in NSA and also unmasked N2O reduction in NR. By comparison, increasing doses of the narcotic standard morphine reduced NSA and NR; these changes in NSA and NR were sensitive to antagonism by naloxone. The benzodiazepine standard diazepam produced a dose-related reduction in NR while reducing NSAd only at higher doses. These data indicate that N2O influences on NSA and NR resemble neither morphine nor diazepam. In addition, it appears that the opioid activity of N2O might mask its antianxiety activity in this particular paradigm.

Effects of brotizolam, a new thieno-triazolo-diazepine derivative, on the central nervous system

The effects of brotizolam, a new thieno-triazolo-diazepine derivative, on the central nervous system were analyzed in mice, rats and rabbits. Diazepam, estazolam and triazolam were used as control drugs. Brotizolam inhibited spontaneous motor activities; performances in the rotarod test, staircase test, and maximal electroshock seizure test; and pentetrazol- or bemegride-induced convulsion. Moreover, catalepsy inducing action and potentiating effect on sleep elicited by pentobarbital or ethanol were observed. Following intraperitoneal or oral administration of brotizolam to rabbits with chronically implanted electrodes, the electroencephalographic profile in spontaneous EEG was characterized by slow waves with high amplitudes in the neocortex. The arousal responses by stimulation of the midbrain reticular formation and posterior hypothalamus were slightly inhibited, but the recruiting responses induced by stimulation of the diffuse thalamic projecting system were not inhibited, and seizure discharges induced by stimulation of the dorsal hippocampus were inhibited markedly. When motor activities and pentetrazol-induced convulsions were observed as indices of tolerance for brotizolam, tolerance was not developed by repeated administration of brotizolam up to 14 days. These results suggested that brotizolam, a new thieno-triazolo-diazepine derivative, is judged to be a safer and stronger sleep inducer than diazepam and estazolam.

The staircase test in mice: a simple and efficient procedure for primary screening of anxiolytic agents

The staircase test consists of placing a naive mouse in an enclosed staircase with five steps and observing the number of steps climbed and rearings made in a 3-min period. All the clinically active anxiolytics tested (chlordiazepoxide, clorazepate, diazepam, lorazepam, meprobamate, phenobarbital) reduce rearing at doses which did not reduce the number of steps climbed. The majority of non-anxiolytic substances tested (haloperidol, chlorpromazine, imipramine, amitriptyline, amphetamine, morphine and carbamazepine) produced a parallel reduction of both behavioural variables. Ethosuximide had no effect on behaviour. The anticonvulsant sodium valproate produced an anxiolytic profile in this test, since it reduced rearing, while increasing step climbing. This result confirms the anxiolytic properties of valproate observed in other behavioural models. Our results indicate that the staircase test in mice is simple, rapid and selective for anxiolytics. The test is well suited for use as a primary screening method.

[A simple device for measuring exploratory activity and motility in mice (author's transl)]

A simple apparatus for measuring curiosity and motor activity is described. The practicability of the device for testing psychoactive drugs is demonstrated by several experiments in mice. The results show that curiosity (looking through holes in the side walls of the experimental cage) is often more influenced by drugs than rearing and motor activity.