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Biomedical subjects

H H Samson

Publications and source records attributed to H H Samson.

At least 91 records · Page 5Linked to original sources
PubMed1986

Initiation of ethanol reinforcement using a sucrose-substitution procedure in food- and water-sated rats.

Rats, maintained on free access to both food and water, were trained to press a lever to obtain a 20% sucrose solution. When presentation of the sucrose solution was maintaining responding, low ethanol concentrations were added to the solution. Over 25 sessions, the solution presented as reinforcement was gradually reduced in sucrose concentration until a 10% ethanol solution with no sucrose was presented. Following this initiation procedure, ethanol concentrations up to and including 40% ethanol were found to maintain responding. At the higher ethanol concentrations, the rats consumed doses of ethanol between 0.90 and 0.95 g/kg in the 30-min session. When a concurrent choice between ethanol and water was available in the operant chamber, the rats responded on the lever associated with 10% ethanol presentation. Home cage preference between ethanol and water was found to be altered following the operant ethanol experience with the rats acceptability for 10% ethanol increased prior to the start of the experiment. This initiation procedure provides another manner in which ethanol reinforcement can be instigated in animals that have not been either food- or fluid-deprived. It is hypothesized that mechanisms which may regulate the intravascular and intragastric self-administration of ethanol may also be operating when the oral route is employed.

Alcoholism↗
PubMed1985

Induction and maintenance of ethanol self-administration without food deprivation in the rat.

Rats were trained to lick at a drinking tube containing 5% ethanol to obtain access to a 0.1-ml dipper containing 20% sucrose. Following 20 of these drinking sessions, a lever press response was shaped and maintained with ethanol presentation in the dipper. This induction procedure resulted in rats responding on a FR 8 schedule of reinforcement to receive 40% (v/v) ethanol. Ethanol intakes over 0.5 g/kg in 30 min were obtained when ethanol concentrations over 10% were available. These intakes frequently resulted in blood ethanol levels over 100 mg ethanol/dl blood. This contingent sucrose induction procedure did not use food deprivation at any time. It is suggested that this procedure can be used to investigate the processes involved with the initiation of ethanol as a reinforcer independent of food restriction procedures.

Animals↗
PubMed1985

Oral ethanol self-administration in the rat: effect of naloxone.

Rats responding on a two lever concurrent for ethanol and water, were injected with 5, 10, or 20 mg/kg naloxone hydrochloride 30 min prior to a 30 min session. Only the 20 mg/kg dose had any effect, a decrease in responding for ethanol of up to 50% compared to saline control injection sessions. There were no systematic effects upon water responding. An additional study using sucrose and water as the fluid concurrently available failed to find any effects of naloxone on sucrose responding at the same doses. The effect upon ethanol responding was found not to resemble a pattern of extinction, but rather was best described as a general overall reduction in responding. The relation of these findings to the direct involvement of the endogenous opiate system in ethanol reinforcement is discussed.

Animals↗
PubMed1985

Schedule-induced drinking in humans: a potential factor in excessive alcohol use.

The timed delivery of monetary reinforcement by a computer-controlled slot machine altered the amount of fluid drunk adjunctively by human subjects. In separate experiments, subjects were allowed access to one of three fluids, water, non-alcoholic beer, or alcoholic beer, while receiving monetary reinforcement from the slot machine on one of two Fixed-Interval schedules (FI30 s or FI90 s). The largest difference in intake between the two schedule conditions occurred when water was the fluid available, but a similar trend in consumption was observed in the other studies. Greater consumption occurred when reinforcement was presented on the FI90-s schedule, which was predicted from previous studies using animals. The possible interaction of schedule-induced drinking with other variables known to influence human alcohol consumption is discussed.

Adult↗
PubMed1985

Chlordiazepoxide effects on ethanol self-administration: dependence on concurrent conditions.

Experiments examined the effects of acute doses of chlordiazepoxide upon ethanol self-administration in the rat. A concurrent-schedule procedure was used that employed choice between ethanol (5%) and a second fluid (either water or a 1% sucrose solution). When ethanol and water were the available fluids, chlordiazepoxide at doses of 15 and 20 mg/kg reduced ethanol-reinforced responding and intake, with a greater reduction occurring at the 20 mg/kg dose. However, when ethanol and sucrose were concurrently available, in many rats only the 20 mg/kg dose of chlordiazepoxide reduced ethanol-reinforced responding. The differences in dose response function occurred in most animals without large changes in the baseline ethanol-reinforced responding across the two concurrent conditions. Thus the dose-effect curve relating chlordiazepoxide and ethanol self-administration can be altered, dependent upon the nature of the concurrently available reinforcers.

Animals↗
PubMed1984

Comparison of sucrose-sucrose to sucrose-ethanol concurrent responding in the rat: reinforcement schedule and fluid concentration effects.

Rats maintained at 80% of their ad lib body weight were trained on a two bar concurrent fixed ratio 8-fixed ratio 8 schedule with sucrose solutions presented at schedule completion. When the solutions were available on the same schedule of reinforcement, rats consistently responded more on the lever associated with the higher sucrose concentration over either less concentrated sucrose solutions or water. However, when a preferred 20% sucrose solution was placed on a high fixed ratio requirement (FR64) and a less preferred 2% sucrose solution remained on the lower ratio requirement (FR8), the rats were observed to increase their responding on the lever associated with presentation of the 2% sucrose solution. Response rates for the low concentrated sucrose solution increased to levels comparable to those seen when that solution was paired with water. These results were compared to prior studies using ethanol and sucrose as the available fluids.

Animals↗
PubMed1984

Social drinking in a simulated tavern: an experimental analysis.

Five groups of five male social drinkers, who frequently drank with one another, were observed during a 30-min drinking period in an experimental tavern. Audio/video tapes of each session were rated by two observers for onset and duration of drinking and talking using a computer scoring system. Drinking was found to follow a negatively accelerating function, with session intakes correlated with reported weekly drinking. Group talking was found to increase during the session, supporting previous reports of increased socialization following drinking. Drinking patterns and intakes were found to be comparable to some of the observations from naturalistic tavern settings suggesting that the simulated tavern is an appropriate environment in which to study drinking consequences.

Adult↗
PubMed1983

A microcomputer-based data acquisition system for continuous recording of feeding and drinking by rats.

A monitoring system to continuously record the daily pattern of drinking and eating of rats is described. This system, based on a North Star microcomputer, can record the amount of food ingested with a temporal resolution of +/- 1.0 second and quantitative accuracy within +/- 5%. Drinking behavior is detected using a drinkometer which also has a temporal resolution of +/- 1.0 second. Data are analyzed by computer to determine absolute amounts of consumption and patterns of intake. The patterns of feeding and drinking recorded by this system are similar to those observed using other monitoring devices.

Animals↗
PubMed1983

Neonatal ethanol exposure: effects on adult behavior and brain growth parameters.

Neonatal rats were reared using an artificial feeding technique from postnatal day 4 through 18. On postnatal day 4 through 7, some animals were given ethanol in their milk formula with the remaining animals serving as controls. The ethanol was given in amounts that have been shown to induce microcephaly when animals are examined at 18 days after birth. In this study, on postnatal day 18, all animals were weaned and allowed ad lib food and water until they were sacrificed at 60 days of age. When the animals were 30 days old, they were tested on a battery of behavioral tasks (nose poke, passive avoidance, and open field). No differences were found between the ethanol exposed animals and their controls on passive avoidance or nose poke activity. Ethanol-exposed female animals showed increased activity compared to their controls in the open field. There were no differences in open field activity between the ethanol exposed males and their controls. An examination of brain growth parameters (wet weights, DNA, cholesterol and protein content) showed no difference between the brains of ethanol-exposed males compared to controls at 60 days of age, regardless of brain parameter or brain area studied (forebrain, cerebellum or brainstem). The brains of ethanol-exposed females, however, had considerably less catch-up growth, with the ethanol effect on the cerebellum being very similar to that observed at 18 days of age. The results imply that sex and the time of ethanol exposure may interact to determine the ability of the brain to develop following a neonatal alcohol insult.

Animals↗
PubMed1983

Ethanol reinforced responding in the rat: relation of ethanol introduction to later ethanol responding.

Rats, maintained on ad lib food and water, were trained to lever press on a concurrent schedule using water and sucrose (10% w/v) as the fluids presented contingent on responding. Each fluid was associated with a lever and available on a fixed ratio eight (FR8) response requirement. The lever with which each fluid was paired was alternated daily. When stable responding occurred, ethanol was substituted for water, first at low concentrations, and then slowly increased to 5% (v/v). When stable sucrose-ethanol responding was reached, the response requirement for sucrose was altered to fixed ratio requirements of either FR32 or FR64. Moderate, but unstable increments in the number of ethanol responses occurred during the increased sucrose response requirements. Following the sucrose response requirement manipulation, water was substituted for the sucrose. Ethanol responding was found to fall to or below prior baseline levels. Weight reduction by food restriction failed to increase ethanol responding. The levels of ethanol responding resulting from this introduction procedure were always much lower independent of body weight than previously reported levels found in rats trained to respond for ethanol using a different procedure of initial ethanol introduction.

Administration, Oral↗
PubMed1983

A survey analysis of first intoxication experiences.

In men and women, there has been a significant decrease in the age at first intoxication over the last 20 years. Significant differences were also found between men and women in their drinking partners during their first intoxication.

Adolescent↗
PubMed1982

Ethanol reinforced responding in the rat: a concurrent analysis using sucrose as the alternate choice.

Rats were trained on a two lever concurrent schedule of reinforcement (Fixed Ratio 8 Fixed Ratio 8) with ethanol (5% v/v) and water as the two available fluids. After establishing baseline responding patterns, various concentrations of sucrose (0.05% to 5.0% w/v) were substituted for the water in an ascending series. When water was the alternative fluid, ethanol responding predominated. With increasing sucrose concentration, percent ethanol responding decreased. At sucrose concentrations between 1.00% and 1.25% approximately half of the total responses per session were for each substance. This change in relative responding for the two fluids occurred as a result of increased total responding and not as a result of decreased ethanol responses. When ethanol was paired with either a 3% or 5% sucrose concentration, ethanol responding decreased, with increased sucrose responding. However, when the number of responses required to obtain these sucrose solutions was greatly increased (Fixed Ratio 64), ethanol responding increased to levels of up to twice that of the water ethanol condition. This increased ethanol responding was found to remain in the following ethanol water session after the sucrose schedule manipulation.

Animals↗
PubMed1982

Relative responding on concurrent schedules: indexing ethanol's reinforcing efficacy.

Five rats were trained to lever press on a concurrent schedule resulting in 3 second access to a dipper (0.1 ml) with either ethanlo (5% v/v) or water. Stable concurrent fixed ratio (FR8 FR8) ethanol and water responding was established. The proportion of responses for ethanol relative to the total number responses varied among rats from 77% to 98%. While the absolute number of responses for ethanol varied greatly day to day, the proportion of ethanol responding was stable. Absolute number of responses for ethanol and proportion of ethanol responding both declined as the body weight of the rats was allowed to increase from initial 80% of ad lib to 110%, with absolute responding showing the greater change. It was concluded that the relative measure of responding on a concurrent schedule could be useful as an index of a drug's reinforcing efficacy, but must be interpreted carefully in regards to the context of drug availability.

Animals↗
PubMed1981

Development of physical dependence on t-butanol in rats: an examination using schedule-induced drinking.

Rats were exposed to various concentrations of t-butanol as their only available fluid in either the home cage or a schedule-induced drinking situation previously shown to induce overdrinking of ethanol. When animals consumed at least 3 g/kg/day of t-butanol for 90 days, independent of conditions, withdrawal symptoms were observed. This daily intake occurred only when the concentration of t-butanol was 3% (v/v) or greater. The schedule-induction procedure did not induce t-butanol overdrinking at any concentration tested as it does with ethanol, but its use did result in increased probability of the occurrence of withdrawal symptoms over the home cage condition. In no cases was the severity of withdrawal from t-butanol as great as previously reported for ethanol. When the concentration of t-butanol was increased to 3.5% (v/v), severe toxic reactions were found, that included anorexia, self-mutilation, and deaths from no specific determinable causes.

Animals↗
PubMed1981

Ethanol reinforced behavior assessed with a concurrent schedule.

Oral ethanol (5% v/v) reinforced responding was studied in three rats using a concurrent fixed ratio (FR) schedule with water available at a second lever. First, concurrent (FR8 FR8) responding on both levers for water presentation was established. Then a concurrent (FR8 FR8) water-ethanol presentation schedule was introduced and a food ration was placed in the chamber at the beginning of the session. Within 12 sessions, ethanol responding developed and within-session feeding was discontinued. When stable concurrent water-ethanol performance was achieved, average ethanol responding was 11 times greater than water responding, even when ethanol availability switched from one level to the other. During the one hour session, in some cases, sufficient ethanol was ingested to produce blood ethanol levels between 30 and 50 mg/100 ml. As the ethanol FR requirement was increased for four sessions each to FR10, 12, 14, 16, 18, 20, 40 and 50, rats continued to respond for ethanol, and in some rats, ethanol preference was maintained even when the ethanol FR was 50 while the water FR remained at 8.

Animals↗
PubMed1981

Maternal ethanol consumption and fetal development in the rat: a comparison of ethanol exposure techniques.

Comparison of the polydipsia and liquid diet procedures for ethanol exposure were used in female rats, either before and/or during gestation. Autopsy of the fetuses on day 20 of gestation found a significant weight reduction in the polydipsia-exposed animals that could be attributed to ethanol. No such effect was found in the liquid diet-exposed animals. The data are discussed in relation to the human fetal alcohol syndrome.

Animals↗
PubMed1981

Altered development of brain by neonatal ethanol exposure: zinc levels during and after exposure.

Neonatal rats, exposed to ethanol by use of an artificial rearing technique during the first postnatal week, have been shown to have a 20% reduction in brain weight compared to littermate controls. The mechanisms responsible for this deficit remain to be determined. One hypothesis, which has been suggested that could be responsible for the microcephaly observed in the Fetal Alcohol Syndrome is that human alcoholics have decreased serum zinc levels. It is well documented that zinc deficiency in rats results in microcephaly. Thus, ethanol administered in the diet could result in lowered zinc levels in serum and brain, and hence be the underlying factor for the brain growth deficiency reported. In these studies, serum and brain zinc levels were determined for animals exposed to ethanol using the artificial rearing procedure, and for their littermate controls, artificially reared on the same formula without ethanol. No differences at any time were found in either serum or brain zinc levels. This would suggest that zinc availability could not account for the effects found on brain growth.

Animals↗