Vasopressin and ethanol preference. II. Altered preference in two strains of diabetes insipidus rats and nephrogenic diabetes insipidus mice

Effects of alcohol and psychostimulants on the vasopressin system: behavioral implications

Drug addiction is a chronic brain disease characterized by a compulsion to seek drugs, a loss of control with respect to drug consumption, and negative emotional states, including increased anxiety and irritability during withdrawal. Central vasopressin (AVP) and its receptors are involved in controlling social behavior, anxiety and reward, all of which are altered by drugs of abuse. Hypothalamic AVP neurons influence the stress response by modulating the hypothalamic-pituitary-adrenal (HPA) axis. The extrahypothalamic AVP system, however, is commonly associated with social recognition, motivational and anxiety responses. The specific relationship between AVP and drugs of abuse has been rarely reviewed. Here, we provide an overview of the interaction between the brain AVP system and psychostimulants and alcohol. We focus on the effects of alcohol and psychostimulants on AVP regulation of the HPA axis, their effect on the brain AVP system and their behavioral implications, the influence of the AVP system on addictive behaviors, AVP's organizational effects on the brain and consequently on behavior, and we highlight clinical studies on the relation between the AVP system and drug addiction. Finally, we discuss the data to address areas that need further research to support clinical trials and prevent drug-related disorders. This article is protected by copyright. All rights reserved.

Alcohol preference in mice lacking the Avpr1a vasopressin receptor

[Arg(8)]-vasopressin (Avp), a nonapeptide hormone, is known to regulate blood pressure, water balance, and a variety of behaviors such as anxiety, aggression, and bonding. Although some evidence that Avp modifies ethanol consumption and some of the effects of ethanol on behavior have been reported, the role of Avp in alcohol consumption and preference is poorly understood. The Avp1a receptor (Avpr1a) is ubiquitously expressed in the central nervous system. To determine the role of Avp signaling on the behavioral effects of alcohol, we examined voluntary ethanol consumption in mice with targeted disruptions of the Avpr1a knockout (Avpr1a KO) gene. Avpr1a KO mice displayed both increased ethanol consumption and preference compared with wild-type (WT) mice. Enhanced ethanol consumption was dramatically and reversibly reduced by treatment with N-methyl-D-aspartic acid antagonists. Basal glutamate release was elevated around the striatum in Avpr1a KO mice. Elevation of extracellular glutamate was also produced in WT mice by local application of an Avpr1a antagonist though a dialysis probe, and this elevation was quickly reversed by stopping the perfusion. These results suggest that Avp can inhibit the release of glutamate from the presynaptic terminal via the Avp1a receptor and that elevation of glutamate levels owing to loss of the inhibitory effect via Avp-Avpr1a signaling may play an important role in the preference for ethanol.

Neurokinin Type-3 Receptor Stimulation Impairs Ethanol-Associated Appetitive Behavior in Wistar Rats

OBJECTIVES

Stimulating central neurokinin type-3 (NK-3) receptors decreases ethanol intake in rats. Although paraventricular nucleus of the hypothalamus (PVN) has a high density of NK-3 receptors, their influence on ethanol reinforcement has not been examined. This study's purpose was to assess the effects of intra-PVN infusion of senktide, a NK-3 receptor agonist, on ethanol self-administration. In a follow-up study, senktide's effects on ethanol self-administration after intracerebroventricular (ICV) infusion were examined.

METHODS

Male Wistar rats were trained to self-administer 10% ethanol (10E) in the "Sipper Tube" model described by Samson and colleagues, Guide cannula were then aimed bilaterally at the PVN or unilaterally at the lateral cerebral ventricle. Intra-PVN (5-100 ng/side) or ICV (30-500 ng/rat) effects of senktide on 10E self-administration were also examined as a preliminary test of senktide's selectivity.

RESULTS

Intra-PVN and ICV infusion of senktide reduced the average number of consecutive lever presses and increased the time taken to complete the lever press requirement when 10E served as the reinforcer. Increased duration of the lever-pressing component was observed when senktide was administered prior to 2S self-administration sessions. Neither PVN nor ICV senktide administration significantly altered 10E or 2S consumption.

CONCLUSIONS

These data suggest that stimulation of central neurokinin typ-3 receptors in the Wistar rat reduces appetitive behavior while having little or no impact on consummatory behavior. Ethanol "seeking" appeared more sensitive to disruption by senktide than sucrose "seeking." However, further studies assessing the senktide's effects on sucrose-maintained behavior are needed to verify this hypothesis. Lastly, it is hypothesized that lack of effect of senktide on intake is in part related to the use of outbred Wistar rats in these studies instead of selectively bred rats.

Effects of peptides on animal and human behavior: a review of studies published in the first twenty years of the journal Peptides

This review catalogs effects of peptides on various aspects of animal and human behavior as published in the journal Peptides in its first twenty years. Topics covered include: activity levels, addiction behavior, ingestive behaviors, learning and memory-based behaviors, nociceptive behaviors, social and sexual behavior, and stereotyped and other behaviors. There are separate tables for these behaviors and a short introduction for each section.

Genetic determinants of ethanol reinforcement

In this paper, we present examples of some of the several behaviors which have been taken to indicate the reinforcing efficacy of drugs, including ethanol. Efforts to identify the genetic determinants of these behaviors have employed diverse pharmacogenetic methods. For example, we have used selective breeding to develop mice selected for severe or attenuated ethanol withdrawal and have found that Withdrawal Seizure Prone mice show a greater conditioned preference for ethanol-associated locations than the selected Withdrawal Seizure Resistant line. Similarly, HOT mice, selected for insensitivity to ethanol-induced hypothermia, had greater conditioned place preference after ethanol training than COLD mice, selected for ethanol hypothermic sensitivity. We have also developed selected mouse lines responsive or unresponsive to ethanol-stimulated locomotor activity. These FAST and SLOW lines develop sensitization rather than tolerance to ethanol-induced activity. Using inbred strains of mice, others had shown that strains differed in preference for drinking ethanol solutions. We found that these strains also differed in acceptance of ethanol. Single-gene techniques have been used to show that preference drinking is significantly altered in mutant rodent strains lacking hypothalamic vasopressin, or with nephrogenic diabetes insipidus. In a specific panel of Recombinant Inbred mouse strains, we found that a single gene appeared to control a significant portion of the variance in preference drinking. These examples show that traits putatively related to drug reinforcement show substantial genetic control. Specifically, single-gene methods show promise of identification and mapping of genes related to drug reinforcement.

Alcohol effects on the morphometric development of the subfornical organ and area postrema of the albino mouse

We have studied the development of the nuclear sizes of ependymocytes and neurons of two circumventricular organs of the male alcoholic mouse: the Subfornical Organ (SFO) and the Area Postrema (AP), comparing the results with a control group. The global volume of both centers was also studied. The results show that the SFO, a structure related to the control of fluid balance, responds to alcoholism with an increase of the global volume. This increase could be related to the variations of salt-water balance and/or blood pressure in chronic alcoholism. However, the size of cell nuclei in the SFO is not affected. In contrast, the AP responds to chronic alcoholism like other nervous centres, with a decrease of the nuclear size of its cells. The global volume of AP does not change.

Central nervous system effects of peptides, 1980-1985: a cross-listing of peptides and their central actions from the first six years of the journal Peptides

A tabular synopsis is presented for articles concerned with the effects of peptides on the central nervous system that appeared in the journal Peptides from 1980-1985. A table arranged alphabetically by peptide and one arranged by effects, both listing routes of injection, species, direction of change, and qualifying notes, provides easy cross-referencing of peptides and their effects. Over 80 peptides and over 135 effects are listed. The list of peptides includes, but is not limited to: ACTH, angiotensin, bombesin, bradykinin, calcitonin, casomorphin, CCK, ceruletide, CGRP, CRF, dermorphin, DSIP, dynorphin, endorphins, enkephalins, GRF, gastrin, LHRH, litorin, metkephamid, MIF-l, motilin, MSH, NPY, NT, oxytocin, ranatensin, sauvagine, substances P and K, somatostatin, TRH, VIP, vasopressin, and vasotocin. The list of effects includes, but is not limited to: aggression, alcohol, analgesia, attention, avoidance, behavior, cardiovascular regulation, catalepsy, conditioned behavior, convulsions, dopamine binding and metabolism, discrimination, drinking, EEG, exploration, feeding, fever, gastric secretion, GI motility, grooming, learning, locomotor behavior, mating, memory, neuronal activity, open field, operant behavior, rearing, respiration, satiety, scratching, seizure, sleep, stereotypy, temperature, thermoregulation and tolerance.