Ciccocioppo R, Lin D, Martin-Fardon R, Weiss F. Reinstatement of ethanol-seeking behavior by drug cues following single versus multiple ethanol intoxication in the rat: effects of naltrexone. Psychopharmacology 168: 208-215
A positive relationship exists between chronic ethanol intoxication experiences and the severity of neural hyperactivity and withdrawal seizures. An important possibility is that withdrawal reactions also influence the motivation to obtain and consume ethanol.
To test this hypothesis, the effects of ethanol-cues on the recovery of extinguished ethanol-seeking and the reversal of this effect by naltrexone, were determined in non-dependent rats and in rats subjected to single versus repeated ethanol intoxications.
Rats were trained to self-administer and discriminate between 10% ethanol and water. Instrumental responding then was extinguished and the effects of exposure to ethanol and water cues were determined. Subsequently, rats were divided into three groups and exposed to control vapor (CTRL), to 12-day ethanol vapor prior to withdrawal (SW), or to three cycles of 3-day intoxication experiences (MW), respectively. Following intoxication, reacquisition and breaking point for ethanol self-administration and cues-induced reinstatement of drug-seeking were investigated.
Ethanol cues significantly reinstated responding in the pre- and post-dependence test, but no significant differences between groups was observed. However, the ability of naltrexone to attenuate the response-reinstatement was significantly reduced in MW rats. Moreover, in the progressive ratio schedule, the breaking points for ethanol were significantly increased in the MW animals.
The results suggest that repeated intoxication did not enhance cue-induced reinstatement of ethanol-seeking. However, naltrexone effects on cues-induced "relapse" appear to be attenuated in MW rats.
"This implication is supported by two groups of experiments. On one hand, evidence indicates that OR antagonists attenuate cue-induced reinstatement of previously extinguished responding for ethanol self-administration (Lê et al., 1999; Ciccocioppo et al., 2002, 2003; Liu and Weiss, 2002; Burattini et al., 2006; Dayas et al., 2007; Marinelli et al., 2009), which suggests a role of EOS in cue-induced incentive motivational effects influencing ethanol-seeking behavior. This interpretation is consistent with clinical data showing that opioid antagonists increase abstinence duration periods in alcohol abusers (O’Malley et al., 1992), probably by reducing cue-induced seeking behavior. "
[Show abstract][Hide abstract] ABSTRACT: Significant evidence implicates the endogenous opioid system (EOS) (opioid peptides and receptors) in the mechanisms underlying the psychopharmacological effects of ethanol. Ethanol modulates opioidergic signaling and function at different levels, including biosynthesis, release, and degradation of opioid peptides, as well as binding of endogenous ligands to opioid receptors. The role of β-endorphin and µ-opioid receptors (OR) have been suggested to be of particular importance in mediating some of the behavioral effects of ethanol, including psychomotor stimulation and sensitization, consumption and conditioned place preference (CPP). Ethanol increases the release of β-endorphin from the hypothalamic arcuate nucleus (NArc), which can modulate activity of other neurotransmitter systems such as mesolimbic dopamine (DA). The precise mechanism by which ethanol induces a release of β-endorphin, thereby inducing behavioral responses, remains to be elucidated. The present review summarizes accumulative data suggesting that the first metabolite of ethanol, the psychoactive compound acetaldehyde, could participate in such mechanism. Two lines of research involving acetaldehyde are reviewed: (1) implications of the formation of acetaldehyde in brain areas such as the NArc, with high expression of ethanol metabolizing enzymes and presence of cell bodies of endorphinic neurons and (2) the formation of condensation products between DA and acetaldehyde such as salsolinol, which exerts its actions via OR.
"When quinine was delivered during the response period, an intermittent beeper was activated and the stimulus light was constantly illuminated (CS−). The stimuli used in the current experiments during the conditioning phase are similar to the predictive olfactory cues (used as either the S+ or the S−) and response-contingent visual and auditory cues used in other studies (e.g., Backstrom and Hyytia, 2005; Ciccocioppo et al., 2002, 2003; Economidou et al., 2007; Liu and Weiss, 2002). Following these last 5 weeks of ethanol self-administration and discrimination training, the rats remained in their home cages for 7 days with free access to food and water only. "
[Show abstract][Hide abstract] ABSTRACT: Cues associated with alcohol can stimulate subjective states that increase relapse. Alcohol-cue associations may be strengthened by enhancing adrenergic activity with yohimbine or weakened by blocking adrenergic activity with propranolol. Alcohol-cue associations may also be weakened by long cue exposure sessions or strengthened by short cue exposure sessions. A useful treatment approach for alcoholism may combine adrenergic manipulation with cue exposure sessions of a specific duration. The present study sought to determine if cue exposure during long- or short-duration extinction sessions with post-session yohimbine or propranolol would alter alcohol cue-induced responding and self-administration. Rats were trained to respond for alcohol during sessions that included an olfactory cue given at the beginning of the session and a visual/auditory cue complex delivered concurrently with alcohol. Cue-induced responding was assessed before and after the repeated extinction sessions. Repeated alcohol extinction sessions of long duration (45 min) or short duration (5 min) were followed immediately by injections of saline, yohimbine, or propranolol. After the second set of cue-induced responding tests, reacquisition of operant alcohol self-administration was examined. To determine if the experimental procedures were sensitive to memory manipulation through other pharmacological mechanisms, the NMDA receptor antagonist MK-801 was given 20 min prior to long-duration extinction sessions. Both the long- and short-duration extinction sessions decreased cue-induced responding. Neither yohimbine nor propranolol, given post-session, had subsequent effects on cue-induced responding or alcohol self-administration. MK-801 blocked the effect of extinction sessions on cue-induced responding but had no effect on self-administration. The present study shows that manipulation of the NMDA system in combination with alcohol cue exposure therapy during extinction-like sessions may be more effective than manipulation of the adrenergic system in reducing the strength of alcohol-cue associations in this specific model of alcohol relapse.
"It should be noted that the doses of NAL that were necessary to block PSR in P rats in our experiment were much higher than the doses necessary to block seeking in other rat models. For example, a 1 mg/kg dose of NAL was sufficient to block cue-induced ethanol-seeking behavior in Wistar rats (Ciccocioppo et al., 2003; Dayas et al., 2007; Liu and Weiss, 2002), and only 0.2 mg/kg dose "
[Show abstract][Hide abstract] ABSTRACT: Research indicates opioid antagonists can reduce alcohol drinking in rodents. However, tests examining the effects of opioid antagonists on ethanol seeking and relapse behavior have been limited. The present study examined the effects of two opioid antagonists on ethanol maintenance, seeking, and relapse responding by alcohol-preferring (P) rats. Adult P rats were self-trained in two-lever operant chambers to self-administer 15% (vol/vol) ethanol on a fixed-ratio 5 (FR5) versus water on a FR1 concurrent schedule of reinforcement in daily 1-h sessions. After 10 weeks, rats underwent extinction training, followed by 2 weeks in their home cages. Rats were then returned to the operant chambers without ethanol or water to measure responses on the ethanol and water levers for four sessions. After a subsequent 2 weeks in the home cage, without access to ethanol, rats were returned to the operant chambers with ethanol and water available. Effects of antagonists on maintenance responding were tested after several weeks of daily 1-h sessions. Naltrexone (NAL; 1-10mg/kg, subcutaneously [s.c.]; n=8/dose), LY255582 (LY; 0.03-1mg/kg, s.c.; n=8/dose), or vehicle were injected 30min before the first session (in the absence of ethanol), following 2 weeks in their home cages, and for four consecutive sessions of ethanol self-administration under maintenance and relapse conditions. Both NAL and LY reduced responses on the ethanol lever without any fluids present, and ethanol self-administration under relapse and on-going drinking conditions, with LY being more potent than NAL. Both NAL and LY were less effective in reducing responding in the absence of ethanol than in reducing ethanol self-administration. Overall, the results indicate that the opioid system is involved in mediating ethanol seeking, and ethanol self-administration under relapse and on-going alcohol drinking, but that different neurocircuits may underlie these behaviors.
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.