Animal model of alcoholism: critique and progress

Making animals alcoholic: shifting laboratory models of addiction

The use of animals as experimental organisms has been critical to the development of addiction research from the nineteenth century. They have been used as a means of generating reliable data regarding the processes of addiction that was not available from the study of human subjects. Their use, however, has been far from straightforward. Through focusing on the study of alcoholism, where the nonhuman animal proved a most reluctant collaborator, this paper will analyze the ways in which scientists attempted to deal with its determined sobriety and account for their consistent failure to replicate the volitional consumption of ethanol to the point of physical dependency. In doing so, we will see how the animal model not only served as a means of interrogating a complex pathology, but also came to embody competing definitions of alcoholism as a disease process, and alternative visions for the very structure and purpose of a research field.

Craving for alcohol in the rat: adjunctive behavior and the lateral hypothalamus

A review of previous results and the new data in this report show clearly that the Falk model of adjunctive behavior is an adequate analogue of human alcoholism and can be applied to induce excessive ethanol consumption. New data on the consumption of sweet flavored ethanol solutions and, especially, sweet alone solutions during brief periods of ethanol withdrawal provide some significant insights concerning the possible physiological basis for cravings in humans. Because voluntary consumption of ethanol is the normal process by which alcoholism develops, a general set of environmental and other experimental conditions that produce behavioral excess; adjunctive behavior, electrical stimulation of the brain, and salt arousal of drinking are discussed in some detail. Neuronal circuits of the lateral hypothalamus are important because some of the cells are chemosensitive and monitor osmolality of the blood and initiate drinking in the normal regulation of body fluids. Alcohol in very small amounts has a direct effect on these cells that also project to lower spinal motor neurons and modulate the level of excitability in spinal reflexes and thereby reactivity to environmental stimulation. Taste and other sensory information from the mouth arrives in presynaptic endings on these same cells by a multitude of indirect multisynaptic pathways. A theoretical model is developed to explain how tactile and taste sensory information and what is initially a nonspecific general state of motor arousal interact together to produce an excessive consumption or craving for ethanol.

What schedule-induced polydipsia can tell us about alcoholism

An animal model of chronic and excessive voluntary (unforced) alcohol ingestion is presented in which, by drinking, animals produce repeated, substantial elevations in blood ethanol concentration and develop physical dependence. The overindulgence is elective in that ethanol is chosen in preference to certain other fluid-ingestive alternatives. Beside the usual demonstrations of acutely compromised motor performance, tolerance development, cross-tolerance, etc., the model demonstrates that the consequences of even short, but continued, daily drinking episodes results in the disruption of reinforced behavior that occurs later in the day when blood ethanol is absent (impaired general functioning). The conditions which induce the ethanol overindulgence can generate a variety of behavioral excesses which places alcoholism in a context of environmentally determined malfunctions that are subject to therapeutic change by altering situational parameters. Efficacious experiments utilizing therapeutic and preventive strategies are described that may serve as suggestions for corresponding human alcoholism intervention strategies.

Ethanol as a reinforcer for rats: factors of facilitation and constraint

This review examines some particular approaches that have been used to investigate factors that facilitate or constrain the self-administration of ethanol by rats. A technique for increasing ethanol self-administration in rats, the prandial drinking method, was examined and the effect of body-weight reduction on drug intake was discussed. Emphasis was placed on how ethanol intake may be controlled by processes in addition to the direct pharmacological actions of the drug in the CNS. These processes may be physiological. Evidence was presented for a relationship between activity in the renin-angiotensin system and the self-administration of ethanol. These processes may also be environmental. Using the place-conditioning technique, demonstrations were presented of how the context or situation in which ethanol is experienced may determine whether preference or aversion for the drug develops. Such a diversity in the factors that can potentially control ethanol intake may complicate the identification of the causes of alcohol abuse, but this same diversity also holds out greater hope that manipulations may be found to reduce excessive drinking in humans.

A software package for the microcomputer control and analysis of research on schedule-induced polydipsia

This manuscript describes a software package called POLY which offers a range of routines designed to allow the user to set up, run and analyze data for research on schedule-induced polydipsia. The three major routines described are SETUP, RUN and ANALYSIS. The routines are flexible and give the user efficient control over the parameters of the research and the collection and analysis of the data. Although designed for research on schedule-induced polydipsia, the software can be used for other research purposes, requiring only changes in the support hardware.

Brain-gut neuropeptides and the limitation of ethanol consumption

Recent studies have clearly shown powerful control of ingestive behavior by certain peptides known to be present in both brain and gut tissues. These "brain-gut neuropeptides" are thought to constitute endogenous factors responsible for the normal regulation of food intake. This review explores the potential for a role of these peptides in the limitation of ethanol intake, which shares several features with the control of food intake. The putative satiety role of the neuropeptides cholecystokinin and bombesin, and other brain-gut peptides is briefly described. The conclusion that voluntary ethanol intake is partially controlled as a function of the energy ethanol provides, and the rate of its utilization, is illustrated with data from recent studies of rat and hamster ethanol consumption. The possibility of neuropeptide influence on ethanol intake is presented in light of new findings that cholecystokinin and bombesin inhibit ethanol consumption in the rat. If neuropeptides are demonstrated to modulate ethanol intake by eliciting satiety, this information may be useful in the identification and understanding of the endogenous factors which regulate human alcohol intake, and will suggest possible peptide-based therapeutic interventions for control of alcohol abuse and alcoholism.