Biomedical subjects

Richard A Meisch

Publications and source records attributed to Richard A Meisch.

5 recordsLinked to original sources

PubMed2004

Methadone and nicotine self-administration in humans: a behavioral economic analysis.

RATIONALE: Prior research has revealed inconsistencies in the behavioral relations between nicotine and opiates among methadone-maintained patients. OBJECTIVES: The current study examined whether the drug reinforcers cigarette puffs and methadone were economic complements or substitutes. METHODS: Five methadone-maintained, nicotine-dependent participants were trained to self-administer methadone, cigarette puffs, or concurrently available methadone and puffs. Following training, the fixed ratio (FR) value ("price") was increased across sessions (FR 32, 64, 128, 256, and 512), first for methadone and then for puffs. Subsequently, methadone and puffs were concurrently available, and the price of each drug was increased independently, while the price of the alternative (puffs or methadone) remained constant at FR 32. RESULTS: Demand for methadone and cigarette puffs decreased as a function of increases in methadone and cigarette puff prices, respectively. When methadone and puffs were concurrently available, an increase in methadone's price decreased puff consumption, and demand for methadone was less elastic than when puffs were not concurrently available. An increase in puff price decreased puff and methadone demand, but the elasticity of puff demand was unaffected. The concurrent presence of methadone had no effect on the elasticity of demand for cigarette puffs. CONCLUSIONS: Methadone and cigarette puffs appear to be asymmetric economic complements.

Adult↗

PubMed2004

Direct relation between etonitazene dose and response rate: responding under a single FI per session.

Response-contingent injections of etonitazene (ETZ) have been shown to reinforce rats' lever pressing behavior. The objective of the present study was to determine the relation between response rate and ETZ dose when ETZ was administered subcutaneously once per session by the experimenter contingent upon completion of a 10-min fixed-interval (FI) schedule. When injections of the saline vehicle replaced drug injections, response rates dropped to low levels; rates subsequently increased above saline levels when drug injections were reintroduced, demonstrating that ETZ was serving as a reinforcer. A range of ETZ doses (0.01, 0.1, 1, 5.7, and 10 microg/kg) was administered subcutaneously to six rats, resulting in response rates that were directly related to drug dose. These findings are consistent with other studies that have found an increase in reinforcing effects with increases in drug dose. Thus, studies in which drug is administered once per session may be used to measure the reinforcing effects of drugs directly from rate measures, as the response rate in these studies is unaffected by satiation or direct drug effects.

Animals↗

PubMed2003

Relation between choice of ethanol concentration and response rates under progressive- and fixed-ratio schedules: studies with rhesus monkeys.

RATIONALE: A fundamental problem in the study of drugs as reinforcers is the evaluation of a drug's relative reinforcing effects and changes in such effects. Relative reinforcing effects can be measured by determining the preference for one drug dose relative to another drug dose. However, in IV drug self-administration studies technical limitations make direct comparisons between drug doses difficult. An alternative procedure is to measure the relative persistence of behavior across increases in schedule size. OBJECTIVE: To develop a more rapid method to measure the relative persistence of behavior. Instead of increasing the schedule size across sessions, schedule size was increased within sessions by use of a progressive-ratio schedule (PR). METHODS: Male rhesus monkeys orally self-administered ethanol during daily 3-h sessions. At each concentration responding was measured with fixed-ratio (FR) 8 schedules to obtain baseline values. Subsequently behavior was studied with a PR schedule. Relative persistence of behavior was calculated by dividing the mean response rate under the PR schedule by the mean response rate under the FR8 schedules. To compare these findings with results of choice between concentrations, monkeys were given concurrent access to pairs of ethanol concentrations. RESULTS: The relative persistence of behavior increased with increases in drug concentration. When two concentrations were concurrently available, the higher concentration maintained higher response rates. CONCLUSIONS: The relative persistence of behavior can be efficiently measured by dividing the response rate under the PR schedule by the response rate under the FR schedule. Measures of relative persistence corresponded well with measures of choice and show that relative reinforcing effects increase as dose increases.

Administration, Oral↗

PubMed2002

Relative reinforcing effects of different benzodiazepine doses for rhesus monkeys.

The relative reinforcing effects of different doses of benzodiazepines were determined by giving rhesus monkeys concurrent access to different diazepam and midazolam concentrations. For each monkey a dose response function was obtained using three drug concentrations: low (L), intermediate (I), and high (H). The benzodiazepine and the water vehicle were concurrently available under independent fixed-ratio (FR) schedules. After establishing that each concentration was a reinforcer in comparison to vehicle, relative preference for the different concentrations was examined by making pairs of concentrations concurrently available under independent FR schedules. Three pairs were studied (H vs. L, H vs. I, and I vs. L). With both drugs, higher concentrations maintained greater response rates than lower concentrations. Thus, relative reinforcing effects increased with dose. These findings are similar to those obtained with other reinforcing drugs and provide further evidence that benzodiazepines share significant characteristics with other drug reinforcers. Importantly, absolute response rates (responses per session) obtained when only one drug dose was present were not reliably predictive of subsequent preferences for the dose. Both benzodiazepines served as effective reinforcers in that consistent levels of responding were maintained across doses and above vehicle levels under concurrent FR 32 schedules. As with other reinforcing drugs, the reinforcing effects of benzodiazepines increase with increases in dose over a broad range of values.

Administration, Oral↗

PubMed2002

Relative reinforcing effects of different oral ethanol doses in rhesus monkeys.

The relative reinforcing effects of different doses of orally delivered ethanol were evaluated. Mouth-contact responding by rhesus monkeys was measured under concurrent fixed-ratio fixed-ratio schedules of liquid delivery (0.67 ml/delivery) from each of two spouts during daily 3-hr sessions. Experiment 1 examined persistence of responding with ethanol (2%, 8%, and 32% wt/vol) and water available. When fixed-ratio values from 8 to 128 were tested, the number of ethanol deliveries obtained per session decreased as the response requirement increased. The decrease in deliveries was less at higher than at lower ethanol concentrations, however. Experiment 2 examined choice between two ethanol concentrations under concurrent fixed-ratio 16 schedules (4% vs. 8%, 4% vs. 16%, 8% vs. 16%, 2% vs. 8%, 2% vs. 32%, 8% vs. 32%). Higher concentrations (16%, 32%) generally maintained more responding than concurrently available concentrations of 8% or less. An exception was the observation of a preference for 8% over 32% ethanol. When the fixed-ratio value was increased, however, the relative preference for these two doses was reversed so that 32% ethanol maintained more responding than 8% ethanol. Thus, the direction of the preference depended on the size of the response requirement. These results indicate that the reinforcing effects of ethanol increase with dose.

Alcohol Drinking↗