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Biomedical subjects

D J Sanger

Publications and source records attributed to D J Sanger.

At least 127 records · Page 7Linked to original sources
PubMed1981

The effects of pimozide and of reward omission on fixed-interval behavior of rats maintained by food and electrical brain stimulation.

Pimozide (0.125 to 2.0 mg/kg) was administered to rats whose behavior was maintained by a fixed-interval schedule in which the reward was either food (Experiment 1) or electrical stimulation of the brain (Experiment 2). The effects of the drug were compared with the effects of withholding reward (i.e., extinction) in both experiments. Reward omission and administration of pimozide both resulted in decreases in overall rates of responding and increases in the time taken by the subjects to complete a specified number of fixed-intervals. The typical patterning of responding during the sessions of reward omission was also characteristic of the effects of pimozide with food reward but not with brain stimulation reward. The duration of trains of brain stimulation which was under the control of the subjects in Experiment 2, was not altered by administration of pimozide. The differences between the effects of pimozide on behavior maintained by intermittent food reward or by intermittent brain stimulation reward limits a global interpretation of the effects of neuroleptics.

Animals↗
PubMed1980

The effects of caffeine on timing behaviour in rodents: comparisons with chlordiazepoxide.

Previous research has shown that benzo-diazepines and barbiturates can increase the proportion of response bursts emitted by rats on differential reinforcement of low rate (DRL) schedules. A recent report found that caffeine could exert a similar effect in mice and the present study was carried out to compare the actions of caffeine with those of chlordiazepoxide on DRL responding in rats and Mongolian gerbils. Chlordiazepoxide increased response rates, decreased reinforcement frequencies and increased percentages of response bursts in both species. Caffeine also increased response rates and decreased reinforcement frequencies, but in neither species was the percentage of response bursts systematically increased. d-Amphetamine administered to the gerbils also did not increase the percentages of response bursts. Combinations of caffeine and chlordiazepoxide were administered to the rats and produced effects which were generally additive.

Animals↗
PubMed1980

Differential effects of morphine on food and water intake in food deprived and freely-feeding rats.

In two experiments the effects of a range of doses of morphine (1, 3, 10 and 30 mg/kg) on the food and water consumption of rats were studied. The results of the first experiment showed that in 24 h food-deprived rats, morphine reduced levels of food and water intake. The duration of these actions was dependent upon dose, with only the highest dose (30 mg/kg) producing any effect persisting for longer than 4 hr. In contrast a second experiment showed that morphine increased levels of food and water intake in non-deprived animals. The effect on food intake was most apparent when measurements were taken at 2 hr and after 4 h after drug administration, while water intake remained above control levels for over 6 h. This study shows that the actions of morphine on ingestion of food and water are affected by food deprivation, and the results are consistent with the hypothesised role of endogenous opiates in the mediation of such behaviour.

Animals↗
PubMed1980

Learned taste aversion to saccharin produced by orally consumed d-amphetamine.

Rats were presented with solutions containing both saccharin and d-amphetamine and the development of taste aversions to solutions of either or both of these substances was studied. In Experiment 1 it was found that taste aversions developed to solutions of saccharin (1 mg/ml) which contained amphetamine at concentrations of 0.01, 0.03 and 0.1 mg/ml. Experiment 2 showed that a taste aversion conditioned to a solution of saccharin (2 mg/ml) and amphetamine (0.2 mg/ml) generalised to solutions containing saccharin at concentrations between 0.625 and 20 mg/ml but not to a solution containing only amphetamine. In the third experiment it was found that the degree of generalisation of a taste aversion to lower saccharin concentrations depended upon the concentration used during conditioning trials. When the conditioning concentration was 0.625 mg/ml the aversion generalised to concentrations as low as 0.075 mg/ml but when a 10 mg/ml solution was used for conditioning the aversion did not generalise to concentrations below 2 mg/ml. The characteristics of taste aversions conditioned with orally consumed amphetamine are similar to those of conditioning involving injections of the drug.

Animals↗
PubMed1979

The effects of fenfluramine on schedule-induced drinking in rats.

The lever pressing of rats was maintained by a fixed-interval 60 sec schedule of food reinforcement. Water bottles were available during sessions and high levels of schedule-induced drinking developed. Both fenfluramine (0.5, 1.0, 2.0, 4.0, 8.0 mg/kg) and d-amphetamine (0.25, 0.5, 1.0, 2.0 mg/kg) produced dose related decreases in this drinking with d-amphetamine approximately four times as potent as fenfluramine. d-Amphetamine produced large increases in overall rates of lever pressing and greatly decreased the duration of postreinforcement pauses. Fenfluramine exerted similar actions but at all doses studied these effects were much less than the effects of d-amphetamine on these measures.

Animals↗
PubMed1979

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.

Animals↗
PubMed1978

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.

Animals↗
PubMed1978

Effects of d-amphetamine on temporal and spatial discrimination in rats.

Rats were trained to lever-press for food reinforcers on a multiple schedule that had a fixed-interval (FI) and a differential reinforcement of low rate (DRL) component. Illumination of a stimulus light above the right-hand lever indicated that responses on this lever would be reinforced according to a FI 60-s schedule while responses on the left-hand lever were without programmed consequences. However, when the light above the left-hand lever was illuminated only responses on this lever were reinforced according to a DRL 15-s schedule. When the behaviour of the subjects had been brought under schedule control so that characteristic patterns of FI and DRL responding were emitted and there were relatively few responses on the incorrect levers, the effects of several doses of d-amphetamine (0.25, 0.5, 1.0, and 2.0 mg/kg) were assessed. The drug increased preference for responding on the right-hand lever. Thus, as dosage increased performance tended towards a constant high rate of responding on the right-hand lever throughout a session, with a much lower response rate on the left-hand lever. This result emphasises that the behavioural effects of drugs depend not only on patterns of ongoing behaviour but also on the context in which this behaviour occurs.

Animals↗
PubMed1978

Nicotine and schedule-induced drinking in rats.

In the first experiment 4 rats developed schedule-induced water drinking during daily 1 hr sessions of a fixed-time 1 min schedule of food pellet delivery. Injections of a range of doses (0.25, 0.5, 1.0, 2.0 and 4.0 mg/kg) of nicotine hydrogen tartrate were found to produce a dose related attenuation of water intake. The higher doses also reduced the numbers of entries into the food tray in three rats, while the lowest dose consistently facilitated this behavior in the same animals. In a second experiment schedule-induced water drinking developed in 4 other rats under a similar schedule. Substitution of nicotine solution (0.05 and 0.1 mg/ml) for the water reduced volumes of fluid consumed. However, schedule-induced drinking continued at a rate sufficient for the animals to ing-st average doses of the nicotine salt of up to 8.5 mg/kg. It is concluded that schedule-induced drinking can be used successfully as a method of inducing self-administration of nicotine by rats.

Animals↗
PubMed1977

d-Amphetamine and adjunctive drinking in rats.

In the first experiment four food-deprived rats developed high levels of adjunctive water drinking during daily sessions of intermittent food pellet delivery. When the water was removed and a solution of d-amphetamine sulfate (0.01 mg/ml) put in its place, adjunctive drinking was disrupted towards the end of each session although the rats ingested doses of approximately 0.5 mg/kg daily for over 40 sessions. Consumption of the d-amphetamine solution was increased by injections of several doses of alpha-methyl-p-tyrosine (AMPT). In a second experiment injections of d-amphetamine (0.25, 0.5, 1.0, 2.0 mg/kg) were found to reduce adjunctive water consumption in six rats. It was also found that the actions of the two highest doses of d-amphetamine were reduced by pretreatment with a dose of AMPT (100 mg/kg), which itself slightly reduced levels of drinking. These results suggest that, although adjunctive drinking may be a useful technique for inducing rats to self-administer d-amphetamine, the amount of drug consumed is limited by a direct action of the drug on drinking.

Animals↗
PubMed1976

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).

Animals↗
PubMed1976

Effects of chlordiazepoxide, ripazepam and d-amphetamine on conditioned acceleration of timing behaviour in rats.

The lever-pressing behaviour of three rats was maintained by a schedule in which food reinforcement was obtained by any response which was emitted at least 15 s after the previous response (DRL 15s). When performance on this schedule had stabilised, the animals were presented intermittently with 1-min periods of a white noise stimulus, the termination of which was accompanied by the delivery of a mild electric footshock. This procedure let to reliable increases in response rates furing the stimulus although responding at other times continued to be appropriate to the DRL 15-s schedule. Administration of the benzodiazepine chlordiazepoxide (1, 3, 10, 17 and 30 mg/kg) and of ripazepam (1, 3, 10, 30 and 56 mg/kg), a non-benzodiazepine reported to have anxiolytic properties, increased response rates on the DRL baseline while decreasing the acceleration of responding produced by the preshock stimulus. Baseline response rates were also increased by d-amphetamine (0.25, 0.5, 1.0 and 2.0 mg/kg) and at the higher doses this drug completely abolished the accelerated responding during the preshock stimulus. Although the effects of chlordiazepoxide and ripazepam are consistent with the suggestion that these drugs may attenuate the behavioural effects of aversive stimuli, in this experiment the behavioural effects of d-amphetamine were similar in many respects.

Animals↗
PubMed1976

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.

Animals↗