Biomedical subjects

R W Foltin

Publications and source records attributed to R W Foltin.

134 records · Page 8Linked to original sources

PubMed1982

Intragastric methylphenidate does have effects on the behavior of rats.

The effects of intraperitoneal (2.0-32 mg/kg) and intragastric (8.0-96 mg/kg) methylphenidate on milk intake were determined in two groups of rats. Experimental sessions consisted of 15 min access to a sweetened milk solution each day, seven days a week. Following the determination of baseline intake, a dose of methylphenidate was administered prior to the session once every four days with all rats in each group receiving all doses. Although methylphenidate was equally effective in decreasing milk intake using either route of administration, intraperitoneal methylphenidate was four times as potent as intragastric methylphenidate.

Animals↗

PubMed1982

Behavioral tolerance and cross-tolerance to dl-cathinone and d-amphetamine in rats.

The effects of dl-cathinone (0.25-48 mg/Kg, i.p. and d-amphetamine (0.25-8.0 mg/kg, i.p.) on milk intake in rats were determined before, during and after a period of repeated daily administration of dl-cathinone. Experimental sessions consisted of 15-min access to a sweetened milk solution each day. 7 days a week. After the determination of the acute effects of dl-cathinone and d-amphetamine on milk intake, rats were injected daily with either 4.0 mg/kg of dl-cathinone 15 min before each session and saline 15 min after each session; or saline 15 min before each session and 4.0 mg/kg of dl-cathinone 15 min after each session. Milk intake returned toward base-line levels for animals receiving daily dl-cathinone before the session over a period of 16 sessions, and remained slightly decreased compared to animals that received postsession injections. Dose-response functions for dl-cathinone and d-amphetamine were then redetermined by substituting a test dose for the usual presession injection once every 4 to 5 days. In animals that were receiving presession dl-cathinone, both drugs had less effect, indicating the development of tolerance to dl-cathinone and cross tolerance to d-amphetamine. The development of tolerance to the suppression of milk drinking was contingent upon the relationship of the time of the daily injection to milk availability. Animals that were receiving dl-cathinone after the session did not develop tolerance but were more sensitive to the effects of both drugs on milk intake. Dose-response functions for both drugs determined after 10 drug free days were similar to the initial dose-response functions, indicating the transient nature of the tolerance and supersensitivity.

Alkaloids↗

PubMed1981

Dopamine depletion by 6-hydroxydopamine prevents conditioned taste aversion induced by methylamphetamine but not lithium chloride.

Specific lesions of the central dopaminergic system produced by intraventricular injections of 6-hydroxydopamine with pargyline and desmethylimipramine pretreatment significantly attenuated conditioned taste aversions to a sweetened-condensed milk solution induced by methylamphetamine. Identically treated rats formed an aversion to the milk solution when lithium chloride was utilized. These results suggest that the methylamphetamine-induced aversion is dependent upon intact dopaminergic neurons.

Animals↗

PubMed1981

The aversive stimulus properties of repeated infusions of cocaine.

When the presentation of a novel food to a rat is followed by the administration of certain compounds, including psychomotor stimulants, the animal consumes less of the food on subsequent presentations relative to an animal administered saline. This phenomenon has been termed gustatory avoidance conditioning. Conflicting results have been obtained when cocaine is used in this procedure. Therefore, the possibility that the weak efficacy of cocaine in this paradigm is due to its relatively short duration of action was investigated. Fluid intake was limited to a single 15 min presentation, seven days a week. Following the determination of baseline water in take sweetened milk was given during the session followed by a series of infusions of cocaine through chronic indwelling peritoneal catheters. Four infusions, spaced 15 min apart, of 9.0 mg/kg cocaine induced an avoidance response, while one infusion of 36 mg/kg cocaine followed by three saline infusions did not. This supports the hypothesis that the low efficacy of cocaine in this paradigm is due, at least in part, to its short duration of action.

Animals↗

PubMed1981

The effects of dl-cathinone in a gustatory avoidance paradigm.

When the presentation of a novel food to a rat is followed by the injection of a certain compounds, including many psychomotor stimulants, the animal consumes less of that food on subsequent presentations compared to an animal injected with saline. This phenomenon has been termed gustatory avoidance conditioning. The effect of dl-cathinone, a psychomotor stimulant drug structurally similar to amphetamine, was determined in this paradigm. Fluid intake was limited to a single 15 min presentation, seven days a week. Following the determination of baseline water intake, sweetened milk was presented for five consecutive sessions. There were six groups of rats with each group receiving a different dose of cathinone (0--16.0 mg/kg) five min after the session each day. Following these five days of milk-cathinone pairings, milk intake was significantly decreased only in the rats receiving 16 mg/kg. These results indicate that cathinone which is nearly as potent as amphetamine in many other behavioral measures, is less potent in inducing gustatory avoidance responses.

Alkaloids↗

PubMedDate not supplied

Performance enhancement in a semi-autonomous confined microsociety.

Research in a continuously programmed human experimental laboratory has been directed toward identifying, defining, and expanding generalized knowledge concerning motivational factors within the structure of human behavioral repertoires that maintain and enhance performance. Participants (in groups of three) engaged in a series of repetitive work activities (e.g., word sorting and rug-hooking) for extended periods each day, while living continuously in a residential laboratory. Other parts of the day were spent either interacting socially with other participants or engaging in individual recreational activities. The percentage of time devoted to the various work tasks provided the basis for selecting one activity that occurred with high frequency and one with low frequency. Performance of the low-frequency activity was then required in order to gain access to the high-frequency activity. Under such contingencies, time devoted to the original low-frequency activity increased greatly, and the participants consistently did more than the required amount of the low-frequency work than was necessary to restore access to the restricted work activity. The theoretical significance of these findings resides in the clear demonstration that a time-based model of value applies as well to the enhancement of work-like performance as it does to voluntarily selected or preferred recreational activities.

Achievement↗

PubMedDate not supplied

The effects of D-amphetamine on responding for candy and fruit drink using a fixed ratio and a progressive ratio schedule of reinforcer delivery.

The first purpose of this study was to compare the effects of D-amphetamine (AMPH) on operant responding reinforced under fixed ratio (FR) or progressive ratio (PR) schedules of reinforcement, testing the hypothesis that responding reinforced under a PR operant schedule would be disrupted by lower doses of AMPH than responding reinforced under a FR operant schedule. The second purpose of this study was to test the generalizability of the first hypothesis by comparing the effects of AMPH on responding reinforced by two different reinforcers under both FR and PR operant schedules. Rhesus monkeys had five to six candy and five to six fruit drink sessions per day, and could receive two reinforcers per session. Responding was initially reinforced under a PR procedure, such that the ratio size increased with each subsequent session. The parameters of the PR schedule were individually selected so that monkeys consumed a similar number of candy and fruit-drink reinforcers each day. The effects of oral AMPH (0.5, 0.75, 1.0 mg/kg) on responding were assessed. Responding was then stabilized using a FR schedule with parameters individually selected so that monkeys consumed a similar number of candy and fruit-drink reinforcers each day, and the effects of oral AMPH were again assessed. The PR breakpoint was significantly greater for candy than fruit-drink. AMPH produced dose-related decreases in both candy and fruit-drink intake, but each AMPH dose decreased the number of fruit-drink deliveries to a greater extent than the number of candy deliveries. The results failed to support the hypothesis that responding under PR schedules of reinforcement would be disrupted by lower doses of AMPH.

Animals↗

PubMedDate not supplied

Concentration of cocaine and metabolites in plasma of humans following intravenous administration and smoking of cocaine.

Plasma was obtained from 10 human subjects at various intervals after administration of two rapid doses of cocaine, either intravenously or by smoking, and multiple doses by smoking and intravenously. The plasma was analyzed for COC and its metabolites, benzoylecgonine (BE) and ecgonine methyl ester (EME). Plasma concentrations of COC were found to be dose-dependent. For patients receiving two successive doses of COC intravenously (IV) or by smoking (SM), the average half-life of COC was found to be between 38 and 39 minutes, regardless of the dose or route of administration. Considerable interindividual variation was observed. Multiple doses of both SM and IV COC were administered to three patients in a manner consistent with COC abuse. The maximum COC concentration observed was 1.2 mg/L following a total administration of 316 mg of COC over 90 min. Analysis of BE and EME confirmed that BE is the principle metabolite of COC in blood. All COC was accounted for by BE. EME, when present, did not exceed 5% of the BE concentration.

Cocaine↗