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N A Ator

Publications and source records attributed to N A Ator.

46 records · Page 3Linked to original sources
PubMed1983

Oral self-administration of methohexital in baboons.

Oral self-administration of methohexital was generated in baboons that were food-restricted but not water-deprived. Stable intake of an 8% ethanol solution (two baboons) or water (two baboons) was first established in 3-h-sessions. Increasing concentrations of methohexital (0.005-10 mg/ml) then were substituted with a return to the ethanol or water baseline condition between methohexital conditions. For one baboon in the ethanol baseline condition, drinking was initially suppressed by methohexital substitution, but increased under a food-induced drinking procedure. For all baboons, an inverted U-shaped function generally described the relation between methohexital concentration and volume consumed. Anesthetization was observed at concentrations of 1.6 mg/ml and above. In two-bottle choice tests, three baboons generally drank greater volumes of methohexital than water at concentrations of 0.8 mg/ml and above. After a methohexital-free period of 1-3 months methohexital self-administration was readily reestablished.

Animals↗
PubMed1983

Nicotine self-administration in baboons.

Two experiments were conducted in which responding maintained by nicotine and cocaine was studied under two different schedules of drug delivery. In Experiment 1, nicotine (0.01-0.32 mg/kg IV) was available under a fixed-ratio 2 timeout 15 sec reinforcement schedule. When nicotine was substituted for cocaine or saline, dose-dependent differences in self-administration were evident across the first five sessions, resulting in an inverted U-shaped dose-effect curve. With continued exposure to each nicotine dose, however, number of injections generally stabilized at levels not very different, if at all, from saline; and the terminal dose-effect functions generally were low and flat. In Experiment 2, nicotine (0.01-0.56 mg/kg IV) was available under a fixed-interval 5 min timeout 60 sec reinforcement schedule. Response rates were considerably lower and response patterning was less likely to be scalloped than when responding was maintained by either cocaine or food, but number of injections was higher than those maintained by saline. When fixed-interval value was varied, number of nicotine reinforcements remained low and virtually constant, but number of food reinforcements increased as the fixed interval decreased. The present results, along with those from previous studies, suggest that the ability of nicotine to serve as a reinforcer appears to be strongly influenced by the conditions of drug availability, perhaps more so than for other drugs of abuse.

Animals↗
PubMed1983

Lorazepam and pentobarbital drug discrimination in baboons: cross-drug generalization and interaction with Ro 15-1788.

Four baboons were trained to discriminate lorazepam (1.0 mg/kg i.m.) and two baboons were trained to discriminate pentobarbital (5.6 mg/kg i.m.) in a two-lever drug discrimination procedure. Food delivery depended on 20 consecutive responses on one lever in sessions preceded by an injection of the training drug and on 20 consecutive responses on the other lever after no drug. All baboons reliably completed 100% of the response runs on the appropriate lever in training sessions. Test sessions were conducted in which a drug dose different from the training dose was injected and 20 consecutive responses on either lever produced food. Drug lever responding occurred after a range of lorazepam and diazepam doses in both lorazepam- and pentobarbital-trained baboons. Drug lever responding also occurred after a range of doses of pentobarbital in the pentobarbital-trained baboons but in only one of the four lorazepam-trained baboons. Ro 15-1788 (0.1-1.0 mg/kg p.o.) antagonized the effect of lorazepam but had no effect on the pentobarbital discriminative stimulus. The asymmetrical generalization with lorazepam and pentobarbital suggests a specificity of discriminative stimulus effects that heretofore have not been documented in drug discrimination experiments with benzodiazepines and barbiturates. The selective antagonism of lorazepam by the benzodiazepine-receptor antagonist Ro 15-1788 suggests that the lorazepam but not the pentobarbital discriminative stimulus is mediated at the benzodiazepine receptor.

Animals↗
PubMed1980

Mirror pecking and timeout under a multiple fixed-ratio schedule of food delivery.

Pigeons were trained to peck a key under a multiple fixed-ratio 25 fixed-ratio 175 schedule of food presentation. In the first condition, either a mirror or the opportunity to produce a 30-second timeout were available. In a second condition, mirror and timeout availability were reversed for the two groups. Following a return to the initial condition, mirror and timeout keys were presented together for all birds. Mirror and timeout responses occurred predominantly in the pause in the larger fixed-ratio component, regardless of whether the opportunities for the two responses were available singly or together. Mirror responding occurred in a greater proportion of the pauses than did timeouts. When the opportunities for both mirror pecking and timeout were available concurrently, they occurred with probabilities similar to those under the single conditions. Within the pause itself, mirror responses most frequently occurred immediately after reinforcement. Timeouts occurred most frequently toward the end of the pause, and some timeouts occurred in the early part of the run. Longer preratio pausing occurred in the larger fixed-ratio component in the conditions in which the mirror was present, whether or not any mirror pecks were recorded.

Journal Article↗
PubMed1979

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.

Animals↗
PubMedDate not supplied

Modulation of the behavioral effects of carbon monoxide by reinforcement contingencies.

Behavioral effects of carbon monoxide (CO) were studied in rats during 75-minute exposures in which food reinforcement depended either on 30 lever presses (fixed ratio, FR, 30) or on the first lever press after 3 min (fixed interval, FI, 3 min). Concentrations of 500, 700, and 900 ppm were studied for each rat under at least one of the reinforcement schedules presented singly and under one or more compound schedules (multiple (MULT) FR FI, MULT FR FR, MULT FI FI). Response rates decreased as a function of CO concentrations under all conditions, but overall rate decreases were greater at lower concentrations under the FR schedule than under the FI schedule. Differential effects of CO on the schedule-generated patterns of FR and FI responding were responsible for the differences in rate decreases under those schedules. In some cases, the multiple schedule context attenuated the rate-decreasing effect of CO on FR responding. Differences in magnitude of CO effects were not attributable to previous CO exposures, control response rates, or reinforcement frequency. The extent to which CO disrupts behavior can be a function of the prevailing behavioral contingencies.

Animals↗