Effects of chlordiazepoxide and flumazenil on preference for punished and unpunished response alternatives in rats

Male food-restricted hooded rats were trained to respond on a two-component multiple schedule. Reinforcement density was several times higher in one component than in the other. However, responses were intermittently punished with shock in the richer reinforcement component (conflict situation). Shock intensities were adjusted to produce mild and strong suppression of responding in two separate phases. Half of the rats controlled which component was operating (Preference group) and half did not (Yoked group). The effect of chlordiazepoxide (CDZ; 0, 1, 3, and 10 mg/kg; IP) was measured on component preference and response rate. Chlordiazepoxide increased both time spent in the conflict situation and response rate in that component. This is the first study employing a schedule that permitted these two behavioral indices to be measured independently in a conflict paradigm. Response rates were also increased in the unpunished response alternative, but to a lesser degree than in the conflict situation. The effects of CDZ were at least partially mediated by the benzodiazepine receptor because CDZ's effects were diminished by flumanezil (10 mg/kg; IP), a benzodiazepine antagonist.     

The nature of performance deficit under secobarbital and chlorpromazine in the monkey

The effects of secobarbital and chlorpromazine were studied in monkeys trained on a continuous, rapidly presented successive discrimination task. The subjects were implanted with epidural electrodes to monitor EEG during drug-induced impairment of performance. The analysis was focussed on the phase of drug effect during which both drugs induced intermittent lapses of responding.EEG and behavioral analysis of events following stimulus onset lead to the conclusion that the mechanism of error occurrence is different under the two drugs. The effect of secobarbital was prominent both in correct and incorrect trials; input, integration and output processes seemed to be functional but slowed down. This was inferred from the presence of EEG arousal, late or abortive motor responses (in the case of errors) and prolonged reaction time of correct responses. In contrast to this general, even effect, CPZ affected the performance in an all-or-none fashion. Periods of normal functioning (i.e., correct responses with moderately increased average reaction time) alternated with complete absence of responsiveness including the EEG arousal reaction. These findings support the view that secobarbital suppresses the behavior by affecting the level of wakefulness and thus impairing the functional condition of the whole central nervous system; chlorpromazine on the other hand exerts its effect by selectively blocking input processes subserving the EEG and behavioral arousal.Supported by Grant MH-12568 from the National Institute of Mental Health, Public Health Service.Research Scientist Awardee (5-K-5-MH-14, 915) of the National Institute of Mental Health.     

EEG correlates of impaired attention performance under secobarbital and chlorpromazine in the monkey

The effects of secobarbital and chlorpromazineupon behavior in a continuous, rapidly presented successive (go-no go) discrimination (attention) task were evaluated in six Macaca mulatta monkeys. Simultaneous monitoring of EEG activity from epidural and subcortical electrodes permitted an evaluation of the nature of altered central nervous system events during erroneous performance (errors of omission) on this task. The computer-assisted analysis of pre-stimulus and post-stimulus EEG frequency activity (baseline crossings) suggests that the best measure of attentive behavior from the pre-stimulus EEG is percentage of beta 2 (25–40 cps) activity. No difference could be observed between drugs or among cerebral placements in this regard. This was determined by comparing measures of EEG frequency, pooled for a given test period, with performance from the same test period. On a trial-by-trial basis, however, the beta 2 measure in the pre-stimulus epoch failed to distinguish correct responses from errors of omission.Separation between correct responses and errors of omission is possible if comparisons are made between the changes in percentage of beta 2 activity in the pre-stimulus vs. post-stimulus epochs. For both drugs, the largest absolute change in beta 2 pre- vs. post-stimulus occurs with correct positive trials and the smallest change with correct negative trials. For secobarbital, no difference could be detected between correct and incorrect positive trials. For chlorpromazine, however, there was significantly less change in beta 2 for incorrect positive than for correct positive trials. The results were interpreted in terms of the hypothesis that secobarbital produces errors by depression of the general level of activation whereas chlorpromazine acts by reducing the sensory input which is necessary for correct discrimination performance.Some of these results were presented to the IXth Meeting of the Collegium Internationale Neuropsychopharmacologicum, Paris, France, July, 1974. Supported by USPHS grant No. MH 12568 from the National Institute of Mental Health. The authors are grateful to Dr. Eva Bakay Pragay for her wise counsel.Research Scientist Awardee K05 14915 of the National Institute of Mental Health.     

Analgesic potency of sodium salicylate,indomethacin, and chlordiazepoxide as measured by the spatial preference technique in the rat

The analgesic potency of various doses of sodium salicylate (150, 200, 250, 300, 350 mg/kg), indomethacin (1.5, 2.0, 2.5, 3.0, 3.5, 5.0 mg/kg) and chlordiazepoxide (2.5, 5.0, 10.0, 20.0 mg/kg) were measured using the spatial preference technique. All three agents were active in a wide range of doses indicating that this technique is sensitive to the weak analgesics. The chlordiazepoxide data were interpreted to suggest that this tranquilizing agent may be able to impair the appreciation of the emotional (i.e., aversive) qualities of electric shock, thus reducing the animal's motivation to escape the noxious stimulus. A procedure for computing ED₅₀ estimates was also presented along with a summary of the ED₅₀ values for several standard narcotic and narcotic antagonist analgesics. Since this procedure is a reliable and sensitive index of drug-induced analgesia, it should be useful as a screening procedure in evaluating the analgesic potency of a wide variety of chemical agents.     

Alcohol preference in the laboratory rat induced by hypothalamic stimulation

Wistar rats were induced to drink aversive alcohol solutions by electrical stimulation in the lateral-hypothalamus. They increased their home-cage intake of alcohol over that of control animals. Changes in alcohol-directed behavior continued after termination of the brain-stimulation treatment. Experimental animals developed a preference for alcohol over water, tolerance for increasing doses of alcohol and alcohol dependence, as shown by withdrawal stress. They consumed alcohol even when it was contaminated with quinine. These data suggest the development of an addiction to the alcohol solutions.     

Effects of chlordiazepoxide on schedule-induced water and alcohol consumption in the squirrel monkey

Lever pressing of five squirrel monkeys was maintained by a 3-min fixed-interval schedule of food presentation. 3 monkeys had water concurrently available and, for a second pair of monkeys, initially water, then increasing concentrations of alcohol (1–3% v/v) were present. Substantial amounts of post-pellet drinking occurred with all five monkeys. The amount of water ingested was approximately 100 ml per session, that of 3% alcohol nearly 63 ml. For the monkeys drinking alcohol, increasing concentrations of alcohol decreased both the rate of lever pressing and the volume of fluid consumed. Chlordiazepoxide (1.0–17.0 mg/kg) produced increases in lever pressing and in the schedule-induced consumption of both 3% alcohol and water.     

Enhanced choice of familiar food in a food preference test after chlordiazepoxide administration

Chlordiazepoxide (5.0 and 10.0 mg/kg) increased the time spent eating familiar laboratory chow, in a food-choice test in which both familiar and novel food objects were available. Chlordiazepoxide did not affect the feeding response to the novel food. Prior handling of the rats and repeat testing affected feeding responses in the test, although in ways which were different from and independent of the effect of chlordiazepoxide. Chlordizepoxide may facilitate feeding responses by a direct enhancement of feeding motivation, and not necessarily secondarily by either a release of suppression of feeding or as attenuation of anxiety evoked by unfamiliarity.     

The effects of electric shock on responding maintained by cocaine injections in a choice procedure in the rhesus monkey

A choice procedure was used to determine the ability of electric shock to suppress cocaine-maintained responding in a situation where cocaine was also available on a second level without shock. In each session rhesus monkeys were allowed to self-inject cocaine five times in the presence of a stimulus. Thirty minutes after the fifth injection a second dose of cocaine could be self-injected five times in the presence of a different stimulus. At the onset of the injection of this dose a 5 or 10 mA electric shock was delivered. Thirty minutes later choice trials began in which both stimuli were present and monkeys could choose one of the two doses of cocaine. Electric shock was delivered at the onset of the injection of one of these alternatives. Initially, both doses of cocaine were 0.1 mg/kg. The dose of cocaine associated with electric shock was systematically increased until it was preferred to the dose not associated with electric shock. The results indicate that although responding main-tained by cocaine can be suppressed by punishment, this effect can be attenuated by increasing magnitude of reinforcement.A preliminary report of the present experiment, in part, appeared in Pharmacol. Rev. 27, 343–355 (1975)     

Effects of chronic chlordiazepoxide treatment on novel and familiar food preference in rats

Chlordiazepoxide (CDP) given acutely has been found to have dose-related effects in rats given food preference tests. Low doses selectively increase consumption of familiar food, while high doses increase novel food consumption. The present study examined the effects of three doses of CDP given chronically. All doses (2.5, 5.0 and 10.0 mg/kg) selectively increased novel food eating. There was some evidence for a selective retardation of eating rate for familiar food and an enhanced taste preference for sweet food in CDP-treated rats. However, the overall results suggest that increased consumption of novel food represents an antineophobic action of CDP, which is potentiated by chronic treatment over a low to medium dose range.     

Enhancement by chlordiazepoxide of the anticholinergic-induced locomotor stimulation in mice

Spontaneous locomotor activity has been studied in mice treated with chlordiazepoxide, atropine, and scopolamine, given alone or in combination. Chlordiazepoxide alone increased activity for a short time, while the two anticholinergic drugs produced longer lasting stimulatory effects. Locomotor stimulation was stronger when chlordiazepoxide and anticholinergics were given in combination.     

Toward a mechanism of the anti-aggression effects of chlordiazepoxide in rats

Rats were given chlordiazepoxide (CDP) before testing in the Ulrich and Azrin shock-induced aggression paradigm for 10 consecutive days. CDP significantly decreased shock-induced aggression but fighting rates did not increase over the course of testing with the drug. Thus any tolerance to the general behavioral depressant effect of the drug either did not occur, or the behavioral depression was not responsible for the reduction in aggression.Another group was administered no drug, caffeine, and CDP, alone or in combination in a spontaneous activity test. CDP suppressed activity, caffeine increased activity and the two drugs in combination had antagonistic effects. The same drugs were used alone or in combination to measure their effects on shock-induced aggression. CDP suppressed aggression, caffeine also suppressed aggression and the two drugs together had additive effects. It was concluded that CDP-induced general behavioral depression is not responsible for suppression of aggression but more likely the property of CDP as a c-AMP phosphodiesterase inhibitor is responsible for the anti-aggression effect.This research was submitted by the first author in partial fulfillment of the Masters of Science degree at the University of Massachusetts.This experiment was supported by Faculty Research Funds from the Graduate School at the University of Massachusetts. Chlordiazepoxide was generously supplied by Hoffmann-LaRoche Inc., Nutley, New Jersey. Nancy F. Feldman composed and drew the figures.     

Dose-dependent impairment in the performance of a go-no go successive discrimination by chlordiazepoxide

After learning a light-cued, go-no go successive discrimination to criterion, male Sprague-Dawley rats received 0, 5, or 10 mg/kg chlordiazepoxide on six performance sessions, followed by two drug-recovery (saline) sessions. Chlordiazepoxide impaired discrimination performance in a dose-dependent manner, with animals in the 5 mg/kg dose condition demonstrating tolerance to the drug after two performance sessions. The degree of discrimination impairment in both drug dose conditions paralleled an increase in responding during no-go phases of the performance task. These findings are consistent with a disinhibitory hypothesis of performance impairment and suggest that CDP-drugged animals have difficulty in withholding incorrect responses.These data were presented at the Annual Meeting of the Psychonomic Society, San Antonio, Texas, 1984     

Associative control of tolerance to the sedative and hypothermic effects of chlordiazepoxide

Pavlovian control of tolerance to the sedative and hypothermic effects of chlordiazepoxide (CDP) was demonstrated in two experiments. In Experiment I, drug-experienced rats were repeatedly treated with CDP (30 mg/kg) in one environment (CS+); on alternate days, they were given saline injections in a different environment (CS-). Duration of sleeping and inactivity were used as measures of sedation. A comparable conditioning procedure was used in Experiment II, but tolerance to the hypothermic effect of CDP was the dependent measure. During tolerance testing, rats from both Experiments I and II were given CDP in one of three environments, CS+, CS-, or a novel environment (CSnov). In Experiment I, rats were equally tolerant in all three test environments when duration of sleep was assessed. However, when inactivity was used as the measure of tolerance, rats showed tolerance in CS+ and CS-, and significantly less tolerance in CSnov. Drug-naive controls showed similar nontolerant responses to CDP in all environments, thus ruling out the possibility that the effect of sedation was mediated nonassociatively. In Experiment II, drug-experienced rats showed tolerance to CDP-induced hypothermia in CS+ and CS- but less tolerance in CSnov. A compensatory hyperthermia was observed when these rats were given saline in CS+. There was some evidence for a generalization gradient in the conditional control of tolerance in both experiments.     

Changes in the amnesic and aversive properties of avoidance conditioning with chlordiazepoxide

In two series of experiments the effects were investigated of chlordiazepoxide (CDP) upon acquisition of avoidance behavior in mice using footshock to establish an avoidance response and posttrial electroconvulsive shock (ECS) to retroactively disrupt the retention of that response. The relationship of either footshock and/or ECS during passive avoidance conditioning acquisition following prior drug treatment provided for reduced active avoidance response acquisition where such training was given following assessment of the retention of the passive avoidance behavior. The present experiments suggest that chlordiazepoxide interacts with acquired avoidance behavior such as to modify the amnesic properties of ECS. This may be due to a partial antagonism of the ECS induced retrograde amnesia, or to modification of active avoidance acquisition by drug treatment.     

Enhancement of osmotic- and hypovolemic-induced drinking by chlordiazepoxide in rats is blocked by naltrexone

Recent reports indicate that benzodiazepine-induced hyperphagia can be antagonised by naloxone, an opiate antagonist. Benzodiazepines are also known to facilitate water ingestion in water-deprived rats, and the present study showed that in addition, benzodiazepine treatment can enhance drinking which is elicited by an osmotic tirst stimulus (2 M hypertonic saline) or by a hypovolemic thirst stimulus (20% polyethylene glycol). In both cases, low dose levels of naltrexone (also an opiate antagonist) dose-dependently suppressed the facilitation of thirst-aroused drinking by chlordiazepoxide. Taken with recent biochemical data these behavioral results indicate that the enhancement of ingestive responses by benzodiazepines may depend upon a naloxone-reversible release of endogenous opioid peptides.     

Extinction and reacquisition of differential responding in rats trained to discriminate between chlordiazepoxide and saline

In order to assess the resistance of drug discriminative responding to prolonged reinforcement omission, rats were trained to discriminate between either 6.0 mg/kg PO or 30.0 mg/kg PO. CDP and saline, using a food reinforced (VI40-FR10) operant procedure. Dose generalization tests were conducted for both groups. Sessions were then run without reinforcement while drug (D) and saline (S) administrations were continued (extinction phase). After a maximum of 30 sessions without reinforcement, or when the rats emitted less than ten responses on either lever during three successive sessions (extinction criterion), reinforcement was reinstated. Finally, additional dose generalization tests with CDP were run. The discriminative responding controlled by the D and S administrations was not affected significantly by prolonged reinforcement omission in either group. For both groups, response rates were decreased and latencies to initiate responding were increased during the extinction phase. Response rate reduction occurred more rapidly for the drug condition in the high training dose group. This group also reached the extinction criterion sooner than the low training dose group. The reacquisition process occurred very rapidly. Response rates increased substantially after the first reinforcement had been obtained. After ten reacquisition sessions, response rates and latencies had reached values similar to those observed before extinction was initiated. Data revealed no differences between groups and the course of reacquisition did not differ between the S and D conditions. The generalization tests executed before the extinction phase and after the reacquisition phase yielded similar results and were in agreement with earlier findings. The major conclusion was that the resistance to extinction of the discriminative accuracy was substantial.     

Effects of chlordiazepoxide training dose on the mixed agonist-antagonist properties of benzodiazepine receptor antagonist Ro 15-1788, in a drug discrimination procedure

In experiment 1, rats (n=12) were trained to discriminate the benzodiazepine (BDZ) compound chlordiazepoxide (CDP, 20 mg/kg, IP) from saline in a two-lever food-reinforced procedure, and subsequently were tested for stimulus control with different doses of CDP, Ro 15-1788 (a proposed BDZ receptor antagonist) and Ro 15-1788 plus 20 mg/kg CDP. Ro 15-1788 (0.63–40 mg/kg) dose-dependently antagonized CDP, and induced predominantly saline appropriate responding when administered alone. Thereafter, the same rats were retrained by progressively decreasing the training dose, to discriminate 2.5 mg/kg CDP from saline, and were tested again with the same compounds. Ro 15-1788 (0.16–40 mg/kg) now failed to antagonize CDP (2.5 mg/kg) and increased the percentage of drug-appropriate responding in a dose-related manner when administered alone. In experiment 2, separate groups of rats (n=10) were similarly trained to discriminate either 15 or 3 mg/kg CDP from saline. Tests with CDP, Ro 15-1788 and Ro 15-1788 plus CDP (either 15 or 3 mg/kg) yielded similar results to experiment 1, suggesting that the training dose effects on generalization and antagonism of Ro 15-1788 were not affected by the manner in which the lower CDP dose acquired drug stimulus control. It is concluded that mixed agonist-antagonist properties are apparent after-variations of the BDZ training dose in a drug discrimination procedure.     

Interactions between the reinforcing effects of cocaine and heroin in a drug-vs-food choice procedure in rhesus monkeys: a dose-addition analysis

Rationale Concurrent abuse of cocaine and heroin is a common form of polydrug abuse, but the interactions between the reinforcing effects of cocaine and heroin are poorly understood. Dose-addition analysis is a tool for the quantitative assessment of drug interactions, but this analysis has not been applied to evaluation of the reinforcing effects of cocaine and heroin.Objectives To evaluate interactions between the reinforcing effects of cocaine and heroin using dose-addition analysis.Methods Rhesus monkeys were trained under a concurrent-choice schedule of food delivery (1 gm pellets) and drug injections (cocaine or heroin, 0–0.1 mg kg^–1 injection^–1). Full dose–effect curves were determined for cocaine alone and heroin alone. Subsequently, full dose–effect curves were determined for three fixed-proportion mixtures of cocaine and heroin (fixed proportions of 1:3.2, 1:1 and 3.2:1 cocaine/heroin). Dose-addition analysis was used to assess whether cocaine/heroin interactions were super-additive, additive, or sub-additive.Results Cocaine, heroin, and all cocaine/heroin mixtures maintained dose-dependent and monotonic increases in drug choice and dose-dependent decreases in response rates. Choice dose–effect curves for cocaine/heroin mixtures were shifted to the left of dose–effect curves for cocaine or heroin alone, and dose-addition analysis indicated that cocaine/heroin interactions on drug choice were sub-additive or additive. Cocaine/heroin interactions on response-rate measures were also sub-additive or additive.Conclusions These results confirm that mixtures of cocaine and heroin produce reinforcing effects in rhesus monkeys; however, cocaine/heroin interactions were only or sub-additive or additive. Thus, these results do not support the hypothesis that simultaneously delivered cocaine and heroin produces super-additive reinforcing effects.     

Buspirone, chlordiazepoxide and diazepam effects in a zebrafish model of anxiety

Zebrafish are becoming more widely used to study neurobehavioral pharmacology. We have developed a method to assess novel environment diving behavior of zebrafish as a model of stress response and anxiolytic drug effects. In a novel tank, zebrafish dwell in the bottom of the tank initially and then increase their swimming exploration to higher levels over time. We previously found that nicotine, which has anxiolytic effects in rodents and humans, significantly lessens the novel tank diving response in zebrafish. The specificity of the diving effect was validated with a novel vs. non-novel test tank. The novel tank diving response of zebrafish was tested when given three anxiolytic drugs from two different chemical and pharmacological classes: buspirone, chlordiazepoxide and diazepam. When the test tank was novel the diving response was clearly seen whereas it was significantly reduced when the test tank was not novel. Buspirone, a serotonergic (5HT_1A receptor agonist) anxiolytic drug with some D₂ dopaminergic effect, had a pronounced anxiolytic-like effect in the zebrafish diving model at doses that did not have sedative effects. In contrast, chlordiazepoxide, a benzodiazepine anxiolytic drug, which is an effective agonist at GABA-A receptors, did not produce signs of anxiolysis in zebrafish over a broad dose range up to those that caused sedation. Diazepam another benzodiazepine anxiolytic drug did produce an anxiolytic effect at doses that did not cause sedation. The zebrafish novel tank diving task can be useful in discriminating anxiolytic drugs of several classes (serotonergic, benzodiazepines and nicotinic).     

Effects of chlordiazepoxide upon spontaneous alternation and the hippocampal electrical activity in white rats

Chlordiazepoxide (CDP) at 20 mg/kg, i. p. reduced the rate of spontaneous alternation in hungry rats on 6 successive trials with no particular reward in a T-maze (Experiment I). The result could not be ascribed simply to the drug-produced changes in running speeds; although alternation is usually assumed to be higher in rate with shorter inter-choice intervals, CDP rats ran slightly faster than saline rats. The same dose of CDP depressed the hippocampal theta activity by decreasing its frequency and facilitating regular fast activity of about 30 Hz which was superimposed on the theta rhythm (Experiment II). The reduction of alternation after CDP was explained in terms of the drug's depressant action upon one of the hippocampal functions, characterized by the theta activity, which is assumed to have a significant role in internal inhibition underlying such behaviors as discrimination reversal, passive avoidance, extinction, frustration, habituation and spontaneous alternation.