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Biomedical subjects

R A Meisch

Publications and source records attributed to R A Meisch.

17 recordsLinked to original sources
PubMed1979

Food deprivation increases oral and intravenous drug intake in rats.

Rats given continuous access to etonitazene hydrochloride in their drinking water (5 micrograms per milliliter) more than doubled their drug intake while deprived of food. Another group of rats with implanted jugular catheters self-administered etonitazene (10 micrograms per kilogram) intravenously on a continuous reinforcement schedule, and the number of infusions increased significantly on days when they were deprived of food. These results suggest that feeding condition may be a powerful determinant of drug-reinforced behavior.

Administration, Oral↗
PubMed1979

Effects of food deprivation on etonitazene consumption in rats.

One group of free-feeding rats was given a 5 microgram/ml etonitazene HCl solution as their sole liquid. This group increased their drug intake by 100% when they were partially food-deprived during a 23-day period. Another group that remained food-satiated and received etonitazene for an equal number of days did not show similar increases in drug intake. However, this group drank greater volumes of the etonitazene solution than a food-satiated control group drank of water. These results are contrasted with a fourth group showing a 50% decrement in water intake during similar food-deprived conditions. The food-deprived group drinking etonitazene showed highly erratic drinking patterns compared to all the other groups. Daily liquid intake ranged from 30 to 250 ml in this group, and volumes oscillated from high to low on alternating days. When the food-deprived/food-satiated conditions were replicated in this experimental group, corresponding increases and decreases in drinking reliably occurred. However, during the second food-deprived phase, the large increases occurred almost immediately as contrasted with a gradual increase over 17 days during the first food-deprived phase. This would suggest a learning mechanism may be involved. Self-mutilation and other forms of stereotypy were noted only in food-deprived rats consuming etonitazene.

Animals↗
PubMed1979

Ethanol drinking by rhesus monkeys with concurrent access to water.

Three monkeys were provided concurrent access to water and ethanol in concentrations of either 8, 16 or 32% (w/v) during daily 3-hr sessions. The monkeys were those for whom ethanol had been established as a reinforcer in an earlier study in which only ethanol or water was available. Ethanol was preferred to water at all concentrations and volume of ethanol consumed was inversely related to ethanol concentration. Quantity of ethanol (g/kg of body wt.) consumed remained relatively constant, and blood ethanol determinations confirmed that the monkeys were drinking ethanol. Water drinking occurred at negligible levels except by one monkey at 16 and 32% who followed ethanol drinking bouts by water bouts (chasers) in a manner similar to that reported in other studies. Two monkeys were also provided concurrent access to 8% ethanol and water during 23-hr daily sessions. Under these conditions, ethanol was consumed every few hours to the near exclusion of water. The significance of this study lies largely in its procedure; that is, the development and application of a concurrent water-ethanol preparation in which ethanol serves as a reinforcer for rhesus monkeys. This preparation should be useful in the evaluation of a wide range of factors suspected to control alcoholic drinking.

Alcohol Drinking↗
PubMed1978

Etonitazene as a reinforcer: oral intake of etonitazene by rhesus monkeys.

Drinking of etonitazene HCI was studied in three rhesus monkeys during daily 3-h sessions. As the drug concentration was increased, the number of liquid deliveries decreased, and etonitazene intake (microgram/kg body weight) increased. As fixed-ratio (FR) requirements were increased, rate of responding increased, and liquid deliveries slightly decreased. When water was substituted for the drug, there was a large increase in responding for several sessions, followed by a slow decline to low rates. When etonitazene was reintroduced, responding abruptly increased to previous drug levels. These data suggest that etonitazene can serve as a positive reinforcer when taken orally by rhesus monkeys.

Animals↗
PubMed1978

Ethanol-reinforced behavior of rats with concurrent access to food and water.

Dippers filled with water or an ethanol solution were presented to male Wistar rats contingent on lever-pressing under a concurrent fixed-ratio 1 (water) fixed-ratio 1 (ethanol) schedule. During Phase I, when maintenance feedings were given during instead of following the daily 3-h sessions, the feedings increased drinking of both 8% (w/v) ethanol and water, with 8% ethanol being consumed in greater volumes than water. In Phase II, a 28-day transitional period from the food-deprived to the food-satiated state, continuous access to food during 3-h sessions moderately decreased 8% ethanol intake, and increased water intake and total liquid intake (water plus 8% ethanol). In Phase III, concurrent water and ethanol intake of food-satiated rats was compared over two identical series of ethanol concentrations (8, 11.3, 16, 22.6, 32, and 8% retest). Food was freely available in both the operant conditioning chambers and home cages. The number of dipper presentations of ethanol exceeded presentations of water for each rat at each concentration studied. Presentations of water were low in number and did not vary with the ethanol concentration. As the ethanol concentration was increased, the number of ethanol presentations decreased, while the quantity consumed (mg/100 g body weight/h) generally increased.

Animals↗
PubMed1978

Ethanol drinking by rhesus monkeys as a function of concentration.

Ethanol deliveries maintained fixed-ratio (FR) responding of three rhesus monkeys during daily 3-h sessions. At FR values of 8 or 16, ethanol concentration was varied in the sequence 0 (water), 8, 11.3, 16, 22.6 32, 8, and 0% (w/v). As the ethanol concentration increased, number of liquid deliveries decreased somewhat. Blood ethanol levels were usually greater than 200 mg% and occasionally greater than 300 mg%.

Alcohol Drinking↗
PubMed1977

Establishment of etonitazene as a reinforcer for rats by use of schedule-induced drinking.

Drinking of etonitazene HCl by 6 rats was studied during daily 4-hr sessions. Five related experiments were conducted sequentially. In the first experiment schedule-induced polydipsia was established. Subsequently, etonitazene concentrations (1.25, 2.5 and 5.0 microgram/ml) were substituted for water, and intake of large quantities of the drug occurred. In the second experiment the concurrent food reinforcement schedule was discontinued and lever presses maintained by etonitazene (5 microgram/ml) persisted. In the third experiment the number of lever presses, required per dipper presentation of etonitazene (5 microgram/ml) was increased, and rate of lever pressing increased directly with the response requirement whereas number of dipper presentations remained constant. In the fourth experiment water was substituted for the 5 microgram/ml etonitazene solution. Water responding declined to low rates, but when etonitazene was reintroduced, responding increased to previous levels. Thus, etonitazene (5 microgram/ml) was functioning as a positive reinforcer. In the final experiment, progressive increases in the etonitazene concentration (5, 10, 20 and 40 microgram/ml) resulted in both systematic decreases in response rate and increases in quantity (microgram) consumed.

Animals↗
PubMed1977

Ketamine self-administration by the rhesus monkey.

Intravenously administered ketamine served as a reinforcer of self-administration behavior in rhesus monkeys during daily 2-hour sessions. When the dose of ketamine was varied over a wide range at fixed-ratio schedules of reinforcement of 1, 8 and 64, the response rate was an inverted U-shaped function of the dose. Maximal response rates occurred at progressively higher doses as the fixed-ratio size was increased; drug intake per session was positively related to the dose. When the ketamine dose was held constant and the fixed-ratio was increased in a geometric series, the response rate increased as the fixed-ratio was increased to FR 128 or FR 256; additional increases in fixed-ratio size produced abrupt decreases in response rates. Since the response rate increased linearly as the fixed-ratio was increased geometrically, drug intake was a decreasing function of the response requirement. With respect to magnitude of reinforcement and fixed-ratio response requirement, the data show that ketamine maintains self-administration behavior in a manner similar to that of a number of other drugs and conventional reinforcers.

Animals↗
PubMed1976

Ethanol as a positive reinforcer via the oral route for rhesus monkeys: maintenance of fixed-ratio responding.

Two rhesus monkeys were required to emit 1 to 16 responses (FR 1, 2, 4, 8, and 16) per 0.5 ml delivery of either 8% (w/v( ethanol or water. Ethanol had been established as an effective reinforcer via the oral route in an earlier experiment [4]. At FR 16, responding maintained by ethanol clearly exceeded responding maintained by water for both monkeys. The volume of ethanol intake per session remained nearly constant from FR 1 to FR 16, however, the volume of water consumed per session decreased when FR 16 was required.

Animals↗
PubMed1976

Drinking device for rhesus monkeys.

A drinking device for rhesus monkeys is described which is simple, reliable, and permits intermittent scheduling of liquid availability. The device may be of particular use in oral drug self-administration experiments since the amount of fluid dispensed may be calibrated and spillage is minimals. The system has been successfully used for over 3 years with 9 unrestrained rhesus monkeys.

Animals↗
PubMed1975

Ethanol as a reinforcer for rats: effects of concurrent access to water and alternate positions of water and ethanol.

Water and ethanol solutions were concurrently made available on a continuous reinforcement schedule to 4 food-deprived male albino rats during daily 1-hr sessions in an operant conditioning chamber equipped with 2 levers and 2 liquid dippers. The number of ethanol reinforcements substantially exceeded the number of water reinforcements for each rat at each concentration studied (8, 16, and 32% w/v). Water reinforcements were low in number and did not vary with ethanol concentration. As the ethanol concentration was increased, the number of ethanol reinforcements obtained decreased, while the quantity consumed (mg/100 g of body weight/hr) increased. The highest rate of responding occurred at the beginning of the session.

Alcohol Drinking↗
PubMedDate not supplied

Ethanol-reinforced responding and intake as a function of volume per reinforcement.

Number of ethanol reinforcements obtained and ethanol intake (mg/100 g body weight/hr) of 3 food-deprived rats were measured over a range of dipper volumes during daily 1 hr sessions. The rats had free access to water in their home cages between sessions. Ethanol concentration was 8 percent (W/V); each response was reinforced. As the volume per reinforcement increased, ethanol intake tended to increase while the number of reinforcements obtained decreased systematically. Responding was maintained by 8 percent (W/V) ethanol but not by water.

Alcohol Drinking↗