Effect of chlordiazepoxide on schedule-controlled responding and schedule-induced drinking

Effects of reinforcement amount on attack induced under a fixed-interval schedule in pigeons

Key pecking by pigeons was maintained on a chained fixed-interval 4-min (12-min for 1 subject) fixed-ratio 1 schedule of food presentation. Attacks toward a restrained and protected conspecific were recorded. In the first experiment, the amount of food presented per interval was manipulated across phases by varying the number of fixed ratios required in the terminal link of the chain. Measures of attack for all pigeons during the fixed-interval component increased monotonically as a function of food amount. In the second experiment, two different food amounts alternated within each experimental session under a multiple schedule. For both pigeons in this experiment, measures of attack were higher during the component that delivered the larger food amount per interval. The differences in levels of attack induced by the two food amounts in Experiment 2, however, were not as great as in Experiment 1; apparently this was because attack during the first interval of each component was controlled in part (P-5626) or entirely (P-7848) by the reinforcement amount delivered at the end of the previous component. Attack was also a function of the location of the interfood interval within the session. For both pigeons, attack tended to decrease throughout the session. The results of both experiments suggest that attack is an increasing function of reinforcement amount under fixed-interval schedules, but that this function may be influenced by the manner in which reinforcement amount is manipulated, by the duration of the interfood interval, and by the location of the interfood interval within the experimental session. In general, these results are compatible with theories of induced attack and other schedule-induced behavior that emphasize aversive after-effects of reinforcement presentation.

Behavioural and pharmacological specificity of the effects of drugs on punished schedule-induced polydipsia

Wistar rats were exposed to a multiple fixed-time 30-s food delivery schedule, with an on/off tone signalling the two components. Animals were matched in accordance with the levels of schedule-induced polydipsia. Drinking was then punished in one of the components: half of the rats received lick-dependent 10-s signalled delays and the other half lick-dependent electric shocks. The intensities of the shocks were adjusted to reduce behaviour by the same amount as the delays in food presentation. Unpunished components were used as yoked-control conditions, by presenting delays or shocks independently of the animals' behaviour. D-Amphetamine (0.3-2.0 mg/kg) and cocaine (1.0-10.0 mg/kg) dose-dependently increased (although only slightly) and then decreased schedule-induced polydipsia punished with lick-dependent delays in food presentation, a result not observed in control conditions or when the behaviour was suppressed by lick-dependent electric shocks. Diazepam (1.0-17.0 mg/kg) and pentobarbital (3.0-17.0 mg/kg) dose-dependently increased and then decreased only the schedule-induced drinking punished with lick-dependent shocks. Buspirone (0.1-1.0 mg/kg) and morphine (2.0-5.6 mg/kg) showed either no specific effects or further suppressed schedule-induced drinking. Results of these and previous experiments suggest that the antipunishment effects of drugs depend not only on the precise nature of the drug, but also on the manner in which the behaviour is maintained.

Pharmacological analysis of the effects of benzodiazepines on punished schedule-induced polydipsia in rats

Food-deprived Wistar rats were exposed to a fixed-time 60-s food delivery schedule until they developed schedule-induced polydipsia. Every fifth lick was then followed by an electric shock during two, signalled, 5-min periods, which ran concurrently with the food delivery schedule. Shock intensities were adjusted to reduce licking to 60-70% of the unpunished licking rates. The benzodiazepine full agonists, diazepam (0.3-3.0 mg/kg), chlordiazepoxide (0.3-10.0 mg/kg), oxazepam (0.3-3.0 mg/kg) and the benzodiazepine partial agonist, RU-32698 (3.0-17.0 mg/kg), led to increases in punished responding at intermediate doses and decreases at the highest doses tested. All benzodiazepine agonists brought about dose-dependent decreases in unpunished schedule-induced polydipsia, with doses required to reduce drinking proving higher than doses required to increase punished schedule-induced polydipsia. The antipunishment effect of 0.3 mg/kg of diazepam was dose-dependently antagonized by flumazenil and the benzodiazepine inverse agonist, RU-34000. Flumazenil effects, however, could reflect actions of flumazenil as a partial inverse agonist at GABAA receptors. RU-32698 at 10.0 mg/kg further facilitated the rate-increasing effect of 0.3 mg/kg of diazepam, but at 17.0 mg/kg partially blocked such antipunishment effect. Overall, the present results extend the similarities of the effects of benzodiazepine compounds on adjunctive and operant patterns of behaviour by showing similar interactions within the benzodiazepine receptor complex.

Effects of cocaine on fixed-interval behavior and schedule-induced alcohol consumption in male and female rats

Three male and three female Wistar rats pressed a lever on a fixed-interval 60-s schedule of food reinforcement while they had simultaneous access to an alcohol solution. They were challenged with different doses of cocaine hydrochloride (vehicle, 1, 3, 10, and 30 mg/kg) once lever press rates and lick rates had stabilized. Low doses of cocaine (1 and 3 mg/kg) did not systematically affect lever press rates or lick rates. The administration of 10 and 30 mg/kg cocaine dose-dependently decreased lever press rates and schedule-induced licking to a greater extent in female than in male rats. Lick rates decreased even when cocaine administration did not affect the number of pellets obtained during an experimental session. Lever press rates accelerated throughout the interreinforcement interval during control sessions. Licking was mostly limited to the first 10 s (males) or 20 s (females) after pellet presentation. Cocaine administration did not affect the distribution of lever presses and licks during the interreinforcement interval. The results of the present experiment extend previous observations that cocaine's rate-dependent effects on lever press rates may be limited to situations in which changes in lever press frequency and/or distribution negatively affect reinforcement frequency and/or the physiological consequences of schedule-induced behavior.

Effects of chlordiazepoxide on food anticipation, drinking and other behaviors in food-deprived and satiated rats

Two groups of rats, Deprived and Satiated, were presented with food according to a fixed time 60-sec schedule. They were then injected with saline, 5, 10, and 15 mg/kg of chlordiazepoxide hydrochloride according to a Latin square design. During saline administration time spent visiting the food tray, time spent drinking, number of tray entries and the amount of water ingested were always greater in the Deprived than in the Satiated group; whereas the opposite was true for grooming. As chlordiazepoxide dose increased time spent visiting the food tray increased in both groups, but the effect was bigger in the Satiated than in the Deprived group. Drinking was not affected by the drug. Grooming and sniffing-rearing were reduced as the dose increased.

Suppression of saccharin-induced drinking in the nondeprived rat by low dose diazepam treatment

Access to a highly palatable 0.005 M sodium saccharin solution resulted in considerable overdrinking in nondeprived rats over a 6 hr observation period. Contrary to previous reports documenting benzodiazepine-induced hyperdipsia in animals challenged with thirst stimuli or in animals exhibiting schedule-induced drinking, diazepam (0.1-3.0 mg/kg) had no effect to enhance the intake of the saccharin solution. Instead, diazepam produced a significant suppression of fluid consumption, in a manner not monotonically related to dose. Thus, diazepam (0.3 mg/kg) produced maximal suppression which did not dissipate over a 6 hr period, while diazepam (3.0 mg/kg) had no effect. Possible behavioral mechanisms by which low dose diazepam treatment might reduce the drinking are briefly considered.

Pharmacological properties of tracazolate: a new non-benzodiazepine anxiolytic agent

Tracazolate (ICI 136,753, 4-butylamino-1-ethyl-6-methyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid ethyl ester) demonstrated dose-related anticonflict activity in rats and mice. The potency of tracazolate appears to be one-quarter to one-half that of chlordiazepoxide. No tolerance to the anticonflict activity of either tracazolate or chlordiazepoxide was evident following 12 consecutive days of treatment. Tracazolate exhibits a much greater separation between sedative and therapeutic doses than does chlordiazepoxide. Furthermore, based on rodent studies, tracazolate should be much less likely than the benzodiazepines to potentiate the actions of barbiturates and ethanol in man. Tracazolate potentiated both the anticonvulsant and anxiolytic effects of chlordiazepoxide in rodents. Unlike benzodiazepines, tracazolate enhances the binding of benzodiazepines to its receptor site. These results suggest that tracazolate is a novel agent with potential clinical utility as an anxiolytic drug.

Effects of diazepam on schedule-controlled and schedule-induced behavior under signaled and unsignaled shock

Schedule-controlled lever pressing and schedule-induced licking were studied in rats under a multiple fixed-interval fixed-interval schedule of food reinforcement upon which was superimposed a multiple variable-time variable-time schedule of electric-shock delivery. Shocks were signaled in one component of the multiple schedule and unsignaled in the other. The effects of diazepam upon the suppression of behavior during the signal (conditioned suppression) and during signaled and unsignaled shock (differential suppression) were studied under several shock intensities (Experiment 1) and at increased body weight (Experiment 2). In each study, diazepam led to dose-dependent increases in the rate of pressing and licking during signaled and unsignaled shock, but had little effect on conditioned suppression. the rate-enhancing effects of diazepam depended upon the intensity of shock, nature of the response, and whether or not shocks were signaled. The data was discussed in terms of (1) implications for understanding the effects of signaled and unsignaled shock on behavior, (2) the effects of diazepam on behavior suppressed by response-independent shock, and (3) comparison between operant and schedule-induced behavior.

Effects of psychotropic drugs on FI responding and adjunctive drinking in rats

Effects of d-amphetamine (AM), chlorpromazine (CPZ) and diazepam (DZ) on schedule controlled responding (lever-pressing) and adjunctive drinking under a fixed interval (FI) 1.5 min schedule of food reinforcement in rats were investigated. The drinking was measured with a drinkometer and a lickometer. AM 0.13--1.0 mg/kg SC increased the total responses, and decreased the total amount of drinking and licking counts dose-dependently. A marked response increase in the early portion (0.30 sec component of the FI) and mid portion (30--60 sec component), and decrease of the drinking in the mid portion and terminal portion (60--90 sec component) occurred. CPZ 0.25--2.0 mg/kg SC decreased responses, drinking and licking in proportion with the doses. After CPZ, a response decrease in the mid and terminal portions was observed, but not in the early portion. Higher doses of CPZ decreased the drinking and licking in the whole range of the interval. A small dose of DZ (0.25 mg/kg SC) produced a significant response increase. Higher doses of DZ also increased responding, but the change was not significant. The drinking and licking were suppressed by DZ. A dose-related response increase in the mid portion was observed after DZ, but not in the early and terminal portions except after 0.25 mg/kg. Higher doses of DZ (more than 0.5 mg/kg) decreased drinking and licking throughout the whole range of the FI. The present results suggest that the interpellet distribution of responding, drinking and licking, as well as their total values, yield important information when assessing drug effects on FI responding and adjunctive drinking in rats.

Effects of isoproterenol and chlordiazepoxide on drinking and conflict behaviors in rats

Isoproterenol, a beta-adrenergic agents, induced drinking in water-satiated rats. Isopropeternol exhibited significant anti-conflict activity on water-deprived rats in the Shock-induced Suppression of Drinking (SSD) procedure. Chlordiazepoxide (CDP), at the highest dose tested, also increased drinking in non-deprived naive rats. As expected, CDP demonstrated highly significant anti-conflict activity in thirsty rats (SSD test). These results suggest that in conflict procedures, where food or water is used as a reward, agents that affect the consumatory drive mechanisms could show up as "false positives." Moreover, agents that affect primary drives (e.g., CDP), in addition to their anti-anxiety activity, could show additive activity in such conflict procedures.

Schedule-induced drinking and thirst: a pharmacological analysis

Similar levels of water consumption were induced in two groups of rats by means either of prior fluid deprivation or a schedule of food pellet delivery. Injections of d-amphetamine (0.25, 0.5, 1.0 and 2.0 mg/kg) had similar attenuating effects of drinking induced by both procedures. Chlordiazepoxide (2.5, 5.0, 10 and 20 mg/kg), however, exerted differential actions on schedule-induced and deprivation-induced drinking. Drinking induced by deprivation was facilitated by all doses of this drug while the higher doses decreased levels of schedule-induced drinking. This result emphasises the difficulties involved in using the concept of thirst in explanations of behavior and of drug action.

Differential effects of chlordiazepoxide on comparable rates of responding maintained by food and shock avoidance

Comparable rates and patterns of lever-pressing by rats were obtained under a multiple variable interval schedule of food reinforcement and continuous shock avoidance. Chlordiazepoxide (1.0--17.0 mg/kg) produced increases in food maintained responding at doses that decreased avoidance responding. Removing food, shock, or both in separate individual probe sessions did not produce differential effects. Under certain circumstances, the effects of chlordiazepoxide appear to be best predicted by knowledge of maintaining conditions.

The effects of d-amphetamine and scopolamine on drinking induced by a multiple schedule

Three food-deprived rats obtained food pellets on a multiple fixed-interval fixed-time schedule. During fixed-interval components a 45 mg pellet was made available for a lever-press every minute (FI 1 min). When the fixed-time component was in operation the lever was retracted and a pellet was delivered every minute (FT 1 min) independent of behaviour. A water bottle was available to each subject and similar levels of schedule-induced drinking developed during the two schedule components. The effects of several doses (0.25, 0.5, 1.0, 2.0 mg/kg) of d-amphetamine and scopolamine were assessed on lever-pressing and drinking maintained by this procedure. Both drugs increased rates of lever-pressing at lower doses and reduced levels of licking and water intake at all doses. The patterning of fixed-interval lever pressing was altered by both drugs increasing the proportion of responses emitted during early parts of the intervals. d-Amphetamine also increased the proportion of licks that occurred during early segments of the interfood intervals, while scopolamine had variable effects on patterns of licking. There were no consistent differences in the effects of the drugs on licking induced by the two schedules.

Effects of clozapine, chlorpromazine and diazepam upon adjunctive and schedule controlled behaviors

Two twelve-animal groups of rats were trained to press a lever for food reinforcement under either a fixed ratio 20 (FR 20) or a fixed interval 2 min (FI 2 min) schedule. During the FI 2 min schedule a measure of adjunctive behavior (i.e., drinking) was taken. Each group was then administered various doses of chlorpromazine (2.5, 5.0, 10.0 mg/kg, P.O.), clozapine (2.5, 5.0, 10.0 mg/kg, P.O.) or diazepam (5.0, 10.0, 15.0 mg/kg, P.O.) in a random order. All three drugs reliably reduced FR 20 response rates in a dose dependent manner, but chlorpromazine and clozapine were more potent in this regard. Chlorpromazine reduced FI 2 min responses rates especially in the terminal portions of the fixed intervals while diazepam generally elevated rates primarily in the min-portion of the interval. Clozapine produced a less defined effect on overall responding. All three drugs affected index of curvature. Only chlorpromazine was able to reliably reduce occurrence of adjunctive behavior and reinforcements.

Effects of diazepam on behaviour suppressed by extinction in pigs

Diazepam injected to pigs previously trained to perform an operant response for food according to a continuous reinforcement schedule significantly increased resistance to extinction compared to control pigs. In pigs submitted to a time-out procedure diazepam increased the number of nonreinforced responses at the beginning of the acquisition but was unable to disinhibit suppressed behaviour in the later stages of acquisition when the extinguished behaviour was well acquired. The results are discussed with respect to antiaversive or disinhibitory effects of benzodiazepines and an alternative interpretation, the strengthening of the prevailing behavioural tendency in the animal's repertoire at the time of test, is put forward.

Scopolamine and adjunctive drinking in rats

Nine, food-deprived rats were each given daily sessions during which 60 45-mg food pellets were delivered individually at 60-sec intervals, independently of behaviour. Water spouts were available to the animals and the intermittent delivery of food induced high levels of adjunctive drinking. The administration of scopolamine (0.125, 0.25, 0.5, 1.0 mg/kg) produced a dose-related attenuation of this drinking. A dose of physostigmine (0.2 mg/kg) was found to slightly reduce levels of drinking but this dose did not consistently modify the action of scopolamine on this behaviour. Tolerance was found to occur to the action of the highest dose of scopolamine (1.0 mg/kg).

Effects of diazepam and ripazepam on two measures of adjunctive drinking in rats

Four rats were maintained at 85% of their pre-experimental body weights and were given daily 1 hr sessions during which they were each placed in a test chamber in which a 45 mg food pellet was delivered regularly every min independently of behavior. During these sessions water spouts were available to the rats and all 4 animals developed high levels of adjunctive drinking, a burst of licking typically following the consumption of each food pellet. This behavior was found to be sensitive to the effects of diazepam and ripazepam. Small doses of both drugs increased the volume of water consumed during a session. The number of licks was not increased to the same extent, however. Larger doses of both drugs resulted in decreased numbers of licks and decreased water intake although licking appeared on several occasions to be more sensitive than water intake to this action of the drugs. A possible explanation of these effects is that the drugs affected the topography of the rats' licking at the water spouts. Whatever the mechanism involved, however, these results suggest that in such experiments measures of both water intake and number of licks should be obtained.