Assessment of the anxiolytic, antidepressant, and antioxidant potential of Parquetina nigrescens (Afzel.) Bullock in Wistar rats.

ETHNOPHARMACOLOGICAL RELEVANCE: The recent growing concerns about the multisystemic nature of mental health conditions in the global population are facilitating a new paradigm involving alternative natural, nutritional, and complementary therapies. Herbal remedies despite accounts in literature of their ethnobotanical as alternative remedies for diverse ailments, remain underexplored for psychiatric disorders like anxiety, depression, and insomnia. AIM OF THE STUDY: Hence, the anxiolytic, antidepressant, and antioxidant properties of a hydro-ethanolic leaf extract of Parquetina nigrescens (PN) in male Wistar rats were investigated. MATERIALS AND METHODS: The sedative effect was evaluated using the Diazepam sleeping time test while anxiety was induced with a single intraperitoneal injection of 20 mg/kg pentylenetetrazol (PTZ). This was after pre-treatment with 100, 150, and 250 mg/kg of PN or the standard drugs (1 mg/kg diazepam and 30 mg/kg imipramine) for 14 consecutive days. Behavioral tests (Open Field test, Elevated Plus-Maze test, and Forced Swim test) were performed on days 1 and 14, to evaluate the antidepressant and anxiolytic activities of PN. Oxidative stress and neurochemical markers were determined in the brain homogenates of the animals. RESULTS: The duration of sleep was significantly (p < 0.001) increased in the PN-administered group compared to the control. The behavioral models showed that PN exhibited antidepressant and anxiolytic properties in PTZ-induced animals. Significant reductions were observed in GSH level and SOD activity while MDA, nitrite, and GPx levels were significantly increased in PTZ-induced rats. However, treatment with PN significantly improved brain antioxidant status by ameliorating the PTZ-induced oxidative stress. Dopamine, cortisol, and acetylcholine esterase activity levels were significantly (p < 0.05) elevated while serotonin and brain-derived neurotrophic factors were reduced in PTZ-induced rats compared with the control. CONCLUSION: The PN demonstrated neurotransmitter modulatory ability by ameliorating the PTZ-induced neurochemical dysfunction. Findings from this study showed that PN exhibited sedative, antidepressant, and anxiolytic activities in rats.

Acute chloroquine poisoning: A comprehensive experimental toxicology assessment of the role of diazepam.

BACKGROUND AND PURPOSE: Resurgence in the use of chloroquine as a potential treatment for COVID-19 has seen recent cases of fatal toxicity due to unintentional overdoses. Protocols for the management of poisoning recommend diazepam, although there are uncertainties in its pharmacology and efficacy in this context. The aim was to assess the effects of diazepam in experimental models of chloroquine cardiotoxicity. EXPERIMENTAL APPROACH: In vitro experiments involved cardiac tissues isolated from rats and incubated with chloroquine alone or in combination with diazepam. In vivo models of toxicity involved chloroquine administered intravenously to pentobarbitone-anaesthetised rats and rabbits. Randomised, controlled treatment studies in rats assessed diazepam, clonazepam and Ro5-4864 administered: (i) prior, (ii) during and (iii) after chloroquine and the effects of diazepam: (iv) at high dose, (v) in urethane-anaesthetised rats and (vi) co-administered with adrenaline. KEY RESULTS: Chloroquine decreased the developed tension of left atria, prolonged the effective refractory period of atria, ventricular tissue and right papillary muscles, and caused dose-dependent impairment of haemodynamic and electrocardiographic parameters. Cardiac arrhythmias indicated impairment of atrioventricular conduction. Studies (i), (ii) and (v) showed no differences between treatments and control. Diazepam increased heart rate in study (iv) and as with clonazepam also prolonged the QTc interval in study (iii). Combined administration of diazepam and adrenaline in study (vi) improved cardiac contractility but caused hypokalaemia. CONCLUSION AND IMPLICATIONS: Neither diazepam nor other ligands for benzodiazepine binding sites protect against or attenuate chloroquine cardiotoxicity. However, diazepam may augment the effects of positive inotropes in reducing chloroquine cardiotoxicity. LINKED ARTICLES: This article is part of a themed issue on The Pharmacology of COVID-19. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.21/issuetoc.

Garlic passion fruit (Passiflora tenuifila Killip): Assessment of eventual acute toxicity, anxiolytic, sedative, and anticonvulsant effects using in vivo assays.

Several Passiflora species are known for their sedative and anxiolytic properties. However, the functional properties of Passiflora tenuifila Killip are still unexplored. The objective of this work was to evaluate the phenolic composition and acute toxicity, anxiolytic, sedative, and anticonvulsant effects using in vivo assays. The whole fruit (peel, pulp, and seed) was lyophilized and used for all assays. LC-MS showed 19 phenolic compounds, tentatively identified as flavonoids and phenolic acids. Acute treatment with single doses of up to 2000 mg kg-1 in Wistar rats showed no signs of mortality or toxicity over 14 days. The assay of functional effects was performed with Swiss mice, four groups, received by gavage, doses of P. tenuifila (200 or 400 mg kg-1 body weight), water, and diazepam (as negative and positive control), and behavior tests were performed after 60 min of the treatments. The animals treated with P. tenuifila fruit showed a significant decrease in locomotor activity, indicating a sedative and anxiolytic activity. No significant changes were observed in the rotarod apparatus, suggesting that the P. tenuifila fruit did not cause muscle relaxation. The 400 mg kg-1 dose of P. tenuifila exerted a protective effect against pentylenetetrazole-induced seizures, decreasing the severity and not causing the death of the animals. In conclusion, P. tenuifila showed no acute toxicity and had a promising effect as an anxiolytic agent, hypnotic-sedative and anticonvulsant, which could be related to its composition of flavonoids and phenolic acids.

Noninvasive assessment of altered activity following restraint in mice using an automated physiological monitoring system.

In the laboratory setting, typical endocrine and targeted behavioral tests are limited in their ability to provide a direct assessment of stress in animals housed in undisturbed conditions. We hypothesized that an automated phenotyping system would allow the detection of subtle stress-related behavioral changes well beyond the time-frames examined using conventional methods. In this study, we have utilized the TSE PhenoMaster system to continuously record basal behaviors and physiological parameters including activity, body weight, food intake and oxygen consumption in undisturbed and stressed C57Bl/6J male mice (n = 12/group), with a pharmacological intervention using the conventional anxiolytic, diazepam (5 mg kg-1 i.p.; n = 8/group). We observed significant 20-30% reductions in locomotor activity in the dark phase, with subtle reductions in light phase activity for up to 96 h following a single 2 h episode of restraint stress. A single administration of diazepam reduced plasma corticosterone concentrations by 30-35% during stress exposure when compared to mice treated with vehicle. This treatment did not result in significantly different locomotor activity compared to vehicle within the first 48 h following restraint stress. However, diazepam treatment facilitated restoration of locomotor activity at 72 and 96 h after restraint stress exposure in comparison to vehicle-treated mice. Hence, the use of an automated phenotyping system allows a real time assessment of basal behaviors and empirical metabolism following exposure to restraint stress and demonstrates major and subtle changes in activity persist for several days after stress exposure.

[Assessment of afobazole effects on diazepam withdrawal-induced anxiety in rats].

Long-term administration of benzodiazepines is known to be associated with drug dependence. The aim of the present work was to investigate the effects of non-benzodiazepine anxiolytic afobazole in the treatment of benzodiazepine withdrawal syndrome. Male outbred rats were treated with either diazepam (4.0 mg/kg, i.p.) or vehicle for 30 days and then abruptly withdrawn for 48 h. Animals were tested in the elevated plus maze test. In addition, neurochemical shifts were evaluated in the selected brain structures (striatum, hippocampus, hypothalamus, and frontal cortex) during diazepam withdrawal. Withdrawn animals made fewer entries and spent less time on the open arms than did vehicle-treated rats and demonstrated a decrease in the dopamine level in striatum as compared with vehicle and diazepam-treated ones. Afobazole (5.0 mg/kg, i.p.) effectively (i) ameliorated withdrawal-induced anxiety, returning behavioral pattern in the elevated plus maze test up to levels comparable to that in vehicle-treated animals, and (ii) increased withdrawal-reduced dopamine level (+23.8%, p < 0.05) in striatum. It is suggested that afobazole, due to its multitarget receptor action, can be useful in the diazepam withdrawal-induced anxiety blockade through modulation of dopaminergic system activity.

Assessment of reinforcement enhancing effects of toluene vapor and nitrous oxide in intracranial self-stimulation.

RATIONALE: Despite widespread abuse, there are few validated methods to study the rewarding effects of inhalants. One model that may have utility for this purpose is intracranial self-stimulation (ICSS). OBJECTIVES: This study aims to compare and contrast the ICSS reward-facilitating effects of abused inhalants to other classes of abused drugs. Compounds were examined using two different ICSS procedures in mice to determine the generality of each drug's effects on ICSS and the sensitivity of the procedures. METHODS: Male C57BL/6J mice with electrodes implanted in the medial forebrain bundle were trained under a three-component rate-frequency as well as a progressive ratio (PR) ICSS procedure. The effects of nitrous oxide, toluene vapor, cocaine, and diazepam on ICSS were then examined. RESULTS: Concentrations of 1,360-2,900 parts per million (ppm) inhaled toluene vapor significantly facilitated ICSS in the rate-frequency procedure and 1,360 ppm increased PR breakpoint. A concentration of 40 % nitrous oxide facilitated ICSS in the rate-frequency procedure but reduced PR breakpoint. Doses of 3-18 mg/kg cocaine facilitated ICSS in the rate-frequency procedure, and 10 and 18 mg/kg increased PR breakpoint. Doses of 1 and 3 mg/kg diazepam facilitated ICSS in the rate-frequency procedure, and 3 mg/kg increased PR breakpoint. CONCLUSIONS: The reinforcement-facilitating effect of toluene in ICSS is at least as great as diazepam. By contrast, nitrous oxide weakly enhances ICSS in only the rate-frequency procedure. The data suggest that the rate-frequency procedure may be more sensitive than the PR schedule to the reward-facilitating effects of abused inhalants.

Benefits of using magnesium sulphate (MgSO4) for eclampsia management and maternal mortality reduction: lessons from Kano State in Northern Nigeria.

BACKGROUND: Despite clear emphasis through the Millennium Development Goals, the problem of high maternal mortality persists especially within low and middle income countries. Various studies report remarkably high maternal mortality rates in northern Nigeria, where maternal mortality rates exceed 1,000 deaths per 100,000 live births and eclampsia contributes approximately 40% of maternal deaths. Across Nigeria, diazepam is routinely used for the management of eclampsia. Prior to February 2008, diazepam was widely used for the management of eclampsia in Kano State (within northern Nigeria) with case fatality rate being over 20%. While magnesium sulphate (MgSO4) is recognized as the most effective drug for the management of eclampsia; this study aims to compare MgSO4 therapy with diazepam therapy in terms of case fatality rates and costs. FINDINGS: This retrospective study, including 1045 patients with eclampsia and pre-eclampsia during the years 2008 and 2009, reports a drop in case fatality rates from 20.9% (95% CI: 18.7, 23.2) to 2.3% (95% CI: 1.4, 3.2) among eclampsia patients following the MgSO4 intervention. The study observed no significant difference in the cost of using MgSO4 therapy compared to diazepam therapy. CONCLUSIONS: The study found a remarkable reduction in case fatality rate due to eclampsia in those who received MgSO4 therapy with minimal increase in costs when compared to diazepam therapy. Concerted efforts should be focused on properly introducing MgSO4 into emergency obstetric protocols especially within developing countries to reduce maternal mortality and also impact on health system performance.

An integrated cardiovascular and neurobehavioural functional assessment in the conscious telemetered cynomolgus monkey.

INTRODUCTION: Unwanted effects of drugs on neurobehavioural and cardiovascular functions are normally assessed in separate studies and using different animals. The purpose of this study was to validate, in the monkey, a model that incorporates the neurobehavioural assessment into the Safety Pharmacology cardiovascular study, allowing for an integrated evaluation of these two physiological systems. METHODS: Conscious male cynomolgus (Macaca fascicularis) monkeys (n=4) were given single oral doses of vehicle, D-amphetamine (0.5, 1 and 2 mg/kg) or diazepam (0.5, 1 and 2.5 mg/kg) in a dose-escalation study design. Blood pressure, heart rate, electrocardiogram (ECG), body temperature, locomotor activity and behaviour (by video) were monitored continuously for 24h post-dose. Animals underwent a standardised neurobehavioural test battery which allowed the direct examination of 31 signs, including behavioural responses and neurological examinations, conducted the day before dose, at maximal plasma concentration time (T(max)), and 24 h post-dose. The study was carried out in a first phase with telemetric cardiovascular recording only, and a second phase with telemetric cardiovascular recording and neurobehavioural observations. Results from the second phase of the study were used to evaluate the influence of the direct neurobehavioural examination on the telemetrically acquired cardiovascular parameters. RESULTS: The expected cardiovascular and neurobehavioural changes, based on the pharmacological properties of the compounds tested, were accurately detected. In the second phase of the study the direct neurobehavioural examination caused fluctuations of the telemetric cardiovascular parameters for no more than 20 min from the end of the procedure and this did not alter or jeopardize the analysis and interpretation of the cardiovascular parameters. DISCUSSION: These results confirm the validity of this combined model capable of providing in the cynomolgus monkey a reliable and reproducible neurobehavioural and cardiovascular assessment of candidate drugs during the course of safety pharmacology evaluations.

Repeated assessment of cardiovascular and respiratory functions using combined telemetry and whole-body plethysmography in the rat.

INTRODUCTION: As the currently recommended laboratory techniques for assessing cardiovascular and respiratory functions are telemetry and plethysmography, we therefore combined both in a single rodent model. The purpose of the present work was to assess the potential influence of body growth on the recorded parameters, to verify the sensitivity of the system to detect well known pharmacological effects of reference drugs, and to determine their reproducibility over time. METHODS: Telemetry instrumented rats were enrolled in successive experiments over a total of 5 months. In each run, they were placed in individual plethysmography chambers for 6h, and received a single intraperitoneal injection of vehicle or test compound. Heart rate, blood pressure, body temperature and respiratory parameters were measured in real time. Six of these 16 rats were submitted 5 times at one month intervals to a vehicle injection, and six rats received theophylline (30 mg/kg) twice at 4 months interval. Nine other reference compounds were also tested at a single dose. RESULTS: Analysis of baseline data mainly showed correlations between body weight or age and heart rate, as well as tidal volume. In the five successive runs, handling-induced perturbations were noted in all the parameters during 60 to 90 min. The effects of the different reference drugs were consistent with data published in animals and man. The response to theophylline was qualitatively similar at 4 months interval. DISCUSSION: We established a combined model of telemetry and plethysmography in the conscious rat, allowing the reuse of the animals over several successive pharmacodynamic studies. Although a shift of some parameters, particularly heart rate and tidal volume, was noted with age and body weight, this can easily be managed by appropriate design measures. We showed that the combined system can detect negative or positive effects on both cardiovascular and respiratory functions with enough sensitivity.

Assessment of luteolin (3',4',5,7-tetrahydroxyflavone) neuropharmacological activity.

Since the discovery that certain flavonoids (namely flavones) specifically recognise the central BDZ receptors, several efforts have been made to identify naturally occurring GABA(A) receptor benzodiazepine binding site ligands. Flavonoid derivatives with a flavone-like structure such as apigenin, chrysin and wogonin have been reported for their anxiolytic-like activity in different animal models of anxiety. Luteolin (3',4',5,7-tetrahydroxyflavone) is a widespread flavonoid aglycon that was reported as devoid of specific affinity for benzodiazepine receptor (BDZ-R) binding site, but its psychopharmacological activity is presently unknown. Considering (1) the close structural similarity with other active flavones, (2) the activity of some of its glycosilated derivatives and (3) the complexity of flavonoid effects in the central nervous system, luteolin was submitted to a battery of tests designed to evaluate its possible activity upon the CNS and its ability to interact with the BDZ-receptor binding sites was also analysed. Luteolin apparently has CNS activity with anxiolytic-like effects despite the low affinity for the BDZ-R shown in vitro. Our findings suggest a possible interaction with other neurotransmitter systems but we cannot rule out the possibility that luteolin's metabolites might show a higher affinity for the BDZ-R in vivo, thus eliciting the evident anxiolytic-like effects through a GABAergic mechanism.

An optimised methodology for the neurobehavioural assessment in rodents.

INTRODUCTION: The most widely used test to identify undesired effects of drugs on the central and the peripheral nervous system is the neurobehavioural observation battery adapted from that first described by Irwin in mice. As a neurobehavioural assessment is based on observations; thus, all factors involved need to be controlled and standardised to make the data collected objective, reproducible, reliable and predictive of safety liabilities. METHODS: An observation battery comprising 58 signs with assigned full details of numerical scores was defined, and a standard design with associated recording, presenting and analysing data system was established. Validation studies were conducted with chlorpromazine, amphetamine, diazepam or clonidine given orally to rats or mice, in order to assess if this methodology could clearly differentiate the profile of effects produced by these compounds. The analysis of data from 80 control rats allowed for the assessment of the normal behaviour in order to characterise the inter-individual, daytime-related variability and the habituation of animals to the procedure. RESULTS: The reference compounds induced their typical and expected transient effects on neurobehaviour, observed both in the home cage and open-arena, and on body temperature. In particular, amphetamine induced a stimulation of the nervous system activities and marked hyperthermia. Chlorpromazine, diazepam and clonidine induced depressive, anxiolytic or sedative effects associated with hypothermia. The analysis of data collected in control animals allowed for the identification of 6 signs which scored differently from the assigned normality at the first handling occasion due to the characteristic fear reactions to the unknown, and 9 signs at 8 h post-dose due to the animal's habituation to experimental conditions and handling. DISCUSSION: The neurobehavioural changes expected by reference compounds administration were detected. These results confirm that by using this methodology the normal behaviour of the rat and the mouse, the daytime-related variability and the habituation of animals can be characterised, allowing a refined, reliable and reproducible neurobehavioural assessment of test substances in rodents.

Assessment of the effects of 2 sedation regimens on cardiopulmonary parameters in pediatric dental patients: a retrospective study.

PURPOSE: The purpose of this study was to evaluate the cardiopulmonary effects of 2 sedation regimens during treatment: (1) oral meperidine and hydroxyzine with nitrous oxide (N2O); and (2) oral diazepam and hydroxyzine, submucosal meperidine, and N2O. Nitrous oxide was tapered to oxygen (O2) only 10 minutes following submucosal meperidine administration. METHODS: Sixty-two children were evaluated who met the following criteria: (1) history of uncooperative behavior; (2) ASA I or II; (3) nothing to eat or drink after midnight the night before the appointment; (4) an initial/recall exam prior to the sedation appointment; and (4) patients who met the American Academy of Pediatric Dentistry guidelines for sedation. Regimens I and II included 32 and 30 patients, respectively. A single clinician treated all patients. A Criticare monitor recorded the following at 5-minute intervals: (1) O2 saturation; (2) respiratory rate; (3) heart rate; (4) systolic and diastolic blood pressures; (5) end tidal carbon dioxide concentration; and (6) mean arterial blood pressure. RESULTS: The t test indicated significant differences between the 2 regimens for: (1) heart rate; (2) systolic blood pressure; and (3) diastolic blood pressure (regimen II had higher values). Using the general linear model, no significant differences were found. All cardiopulmonary parameters were within normal limits. CONCLUSION: Regimens I and II had similar cardiopulmonary effects.

Effects of diazepam on the latency of saccades for luminance and binocular disparity defined stimuli.

Saccadic latency is composed of separate sensory and motor processing delays. Therefore, any alteration in the sensory processing should effect the saccadic latency. Because the highest density of benzodiazepine (Bz) binding sites is located in cerebral cortex, sensory processing of stimuli in this cortical area is expected to be substantially effected by administration of Bzs. It is well known that sensory processing of binocular disparity occurs in the cerebral cortical areas and therefore the latency of saccades to stimuli defined by binocular disparity should be substantially affected by Bz intake. In this study, we tested this prediction by comparing the latency of saccadic eye movements for binocular disparity defined stimuli (stereo stimuli) with those for luminance contrast defined stimuli (luminance stimuli), after diazepam or placebo. Eye movements were mainly recorded by use of the magnetic search coil technique, and the study was performed in a randomized, double-blind way. Although diazepam prolonged the latency of saccades for stereo and luminance stimuli, the percentage increases in saccadic latency for the stereo stimuli were significantly larger than those for the luminance stimuli. Saccadic peak velocity, and saccadic amplitude, also significantly decreased after diazepam under conditions of stereo and luminance stimuli. However, there was no significant difference for either saccadic peak velocity or amplitude between the two types of target. The results suggest that the latency of saccades to binocular disparity defined random-dot stimuli could more sensitively reflect the pharmacodynamic effects of Bzs on the cerebral cortex.

Estimation of the number of "true" null hypotheses in multivariate analysis of neuroimaging data.

The repeated testing of a null univariate hypothesis in each of many sites (either regions of interest or voxels) is a common approach to the statistical analysis of brain functional images. Procedures, such as the Bonferroni, are available to maintain the Type I error of the set of tests at a specified level. An initial assumption of these methods is a "global null hypothesis," i.e., the statistics computed on each site are assumed to be generated by null distributions. This framework may be too conservative when a significant proportion of the sites is affected by the experimental manipulation. This report presents the development of a rigorous statistical procedure for use with a previously reported graphical method, the P plot, for estimation of the number of "true" null hypotheses in the set. This estimate can then be used to sharpen existing multiple comparison procedures. Performance of the P plot method in the multiple comparison problem is investigated in simulation studies and in the analysis of autoradiographic data.

Assessment of the multiple discriminative stimulus effects of ethanol using an ethanol-pentobarbital-water discrimination in rats.

Previous drug discrimination studies have elucidated the importance of gamma-aminobutyric acidA (GABAA), N-methyl-D-aspartate (NMDA) glutamate, and serotonin (5-HT) receptor systems in mediating the discriminative stimulus effects of ethanol. The present study used a three-choice operant drug discrimination procedure in an attempt to determine if salient GABAergic effects could be separated from other stimulus effects of 2.0 g/kg ethanol. Adult male Long-Evans rats (n = 7) were trained to discriminate pentobarbital (10.0 mg/kg; intragastrically (i.g.) from ethanol (2.0 g/kg; i.g.) from water (4.7 ml; i.g.) using food reinforcement. Stimulus substitution tests were conducted following the administration of allopregnanolone (1.0-17.0 mg/kg; intraperitoneally (i.p.)), diazepam (0.1-7.3 mg/kg; i.p.), midazolam (0.0056-17.0 mg/kg; i.p.), dizocilpine (0.01-0.56 mg/kg; i.p.), phencyclidine (1.0-5.6 mg/kg; i.p.), CGS 12066B (3-30 mg/kg; i.p.), RU 24969 (0.1-5.6 mg/kg; i.p.) and morphine (1 or 3.0 mg/kg; i.p.). Within the group, allopregnanolone and midazolam completely substituted (> 80%), and diazepam partly substituted (67%) for the discriminative stimulus effects of pentobarbital. Dizocilpine and phencyclidine partly substituted (58 and 57%, respectively) for ethanol without substantial pentobarbital-appropriate responding. RU 24969, CGS 12066B and morphine did not result in complete substitution for either ethanol or pentobarbital, although RU 24969 resulted in partial (68%) pentobarbital substitution. The ability to train the present three-choice discrimination in rats indicates that the discriminative stimulus effects of 10.0 mg/kg pentobarbital were separable from those of 2.0 g/kg ethanol. The results suggest that the pharmacological effects of ethanol, which can control behavior, may seemingly be modified by training conditions (two-versus three-choice discrimination procedures), to the extent that a receptor system prominently linked to the behavioral activity of ethanol (i.e. GABAA) appears no longer to be involved in the interoceptive effects of the drug.

Assessment of the anxiolytic and amnesic effects of three benzodiazepines, diazepam, alprazolam and triazolam, by conflict and non-matching to sample tests in mice.

The anti-conflict and amnesic effects of three benzodiazepines (diazepam, alprazolam and triazolam) po-administered in mice were assessed by a modified Geller Seifter conflict test and a non-matching to sample test using a 4-arm maze with 3 selectable arms, respectively. Diazepam (10 mg/kg), alprazolam (1-10 mg/kg) and triazolam (1 and 3 mg/kg) significantly increased the lever-press in the alarm period (punished responding) under the conflict test. Under the non-matching to sample test, the correct response (CR), but not non-reward response (NR), decreased depending on the delay time. Diazepam (3 mg/kg) significantly decreased the CR under 0-sec delay condition, but not that under 30-sec delay condition. Comparatively higher doses of the benzodiazepines, diazepam (10 mg/kg), alprazolam (1 and 3 mg/kg) and triazolam (0.3 and 1 mg/kg), significantly decreased the CR under both 0- and 30-sec delay conditions. However, no significant change in the NR was produced by any dose of the three benzodiazepines. These results suggest that the decrease in CR during the non-matching to sample test is caused by the impairment of cognitive function rather than working and reference memories, and that such effects appear at doses equal to and/or less than the effective doses for anti-conflict effect. However, the assumption that triazolam has the highest risk of induction of amnesia, as compared to the advantage of sleep induction or relief of anxiety in the benzodiazepine group, was not supported by the present results.

The assessment of residual effects of a single dose of diazepam on visually-defined EEG patterns.

The aim of this single-blind study was to evaluate the residual effects of a 10-mg dose of diazepam on cortical activation 11 h after oral intake. The electroencephalographic segments (from O1-O2) delimited by a sequence of photic stimuli presented every 10 sec during a simple reaction-time task (36 min duration) were arbitrarily classified into nine cerebral patterns (EEGP). EEGP segment classifications were grouped into six peri-stimulus transitions expressed in percentages: alpha-blockade; alpha-persistence; beta-persistence; alpha-induction; activation and deactivation. A sample of 42 young healthy university students (21 females and 21 males) each underwent three counterbalanced experimental conditions (control, placebo and diazepam). Diazepam affected all the subjects, although the women showed a greater number of EEGP transitions which indicated deactivation, than did the men. The results show that this type of visual EEG analysis is a useful technique for detecting the residual effects of benzodiazepines.

[Assessment of anxiolytics (5)--Vogel-type conflict task in mice].

The Vogel-type conflict task, in which drinking of water by animals is punished by electric shock, is well known as a simple conflict procedure, and has come into wide use. This task has almost been established in rats. On the other hand, there are only few reports about application of the task to mice, and such studies have not proceeded smoothly. This report presents technical problems in the application of the task to mice based on various experiments, in which experimental conditions such as procedures, intensity of electric shock and mouse strain differed, in order to determine the anti-conflict action of diazepam (DZ). These experiments showed that successful detection of DZ action depended upon the experimental conditions. Therefore, experimental designs are important in evaluating anti-conflict action of chemicals in the Vogel-type task in mice.

[Assessment of anxiolytics (2)--An elevated plus-maze test].

When rodents are placed on an elevated plus-maze which consisted of two enclosed arms and two open arms, they enter the enclosed arms more frequently and spend more time on the enclosed arms than on the open arms since they prefer the enclosed arms to the open arms. The elevated plus-maze test can measure effects of drugs based on this tendency of rodents. Anxiolytics increase the time spent on the open arms and number of entries into open arms, and anxiogenics decrease them. We investigated the basal behavior of mice and the effects of diazepam in the elevated plus-maze test using 4 mazes with different size. The basal behavior of mice were changed by the maze size, especially by the width of the open arms. Further, we suggested that the maze size might affect anxiolytic activity of drugs detected in this test. This test is very useful because it needs neither complicated training for rodents nor an expensive apparatus, and the anxiolytic effects of drugs can be easily measured. However, this test is difficult to detect putative anxiolytics acting on serotonin receptors. When this method is used for measuring the activity of drugs, the choice of experimental conditions and evaluation of the results should be carefully done.

Benzodiazepines promote the intermediate stage at the expense of paradoxical sleep in the rat.

The effects of diazepam, a long half-life benzodiazepine, midazolam and triazolam, two with short half-life, on the transitional stage between deep slow wave sleep and paradoxical sleep were studied in Wistar and WAG/Rij rats. This intermediate stage is characterized by the unusual association of cortical spindles and low frequency hippocampal theta rhythm. The main result was extension of the intermediate stage at the expense of paradoxical sleep by diazepam and triazolam by influencing only the duration of the intermediate stage and both the onset and maintenance of paradoxical sleep. Midazolam increased both intermediate stage and paradoxical sleep. Several differences in the qualitative modulation of the stage characteristics and between rat strains were found. In regard to the possible peculiar physiological significance of the intermediate stage, we conclude that benzodiazepines promote a transient pharmacological cerveau isolé-like stage during sleep in rats.