RESUMEN
We examined a possible relationship between genes responsible for energy metabolism of the brain and addictive behavior in an animal model. We used non-inbred, Swiss mice exposed to a three-bottle free-choice model [water, 5% (v/v) ethanol, and 10% (v/v) ethanol] over a 16-week period, consisting of four phases: acquisition, withdrawal, reexposure, and quinine-adulteration. The mice were then behaviorally classified into three groups: loss-of-control-drinker (preference for ethanol and high levels of consumption during all phases, N = 6), heavy-drinker (preference for ethanol and high levels of consumption during acquisition and reduction during quinine-adulteration, N = 7), and light-drinker (preference for water during all phases, N = 10). Another group only received tap water (ethanol-naive control mice, N = 9). Further analysis using quantitative real-time PCR showed that in mice behaviorally classified as loss-of-control-drinkers, there was a significant inverse correlation between transcript levels of the Hadh gene and those of other energy metabolism genes in the nucleus of the amygdala, suggesting that this pathway may contribute to ethanol consumption in these mice. We conclude that cerebral energy metabolism is involved with ethanol addiction, meriting further study.
Asunto(s)
Alcoholismo/genética , Amígdala del Cerebelo/citología , Química Encefálica/fisiología , Metabolismo Energético , Receptores de GABA-B/metabolismo , Consumo de Bebidas Alcohólicas/genética , Alcoholismo/metabolismo , Animales , Conducta Adictiva/genética , Modelos Animales de Enfermedad , Etanol/administración & dosificación , Masculino , RatonesRESUMEN
Several substances that inhibit the induction or expression of behavioral sensitization have been proposed, but patients who present for treatment often have already an established sensitized drug response. Serotonergic agents, including serotonin-2 (5-HT(2)) antagonists, reverse cocaine sensitization, but there is no evidence for the same effect with ethanol, although serotonin involvement in ethanol sensitization has been well reported. To evaluate a 5-HT(2C) antagonist effect on reversing established ethanol sensitization, three experiments were performed assessing locomotor activity of mice under different treatments. First, mice received daily intraperitoneal saline (S), mianserin 10 (M1) or 20 mg/kg (M2), ethanol 2 g/kg (E), or ethanol+mianserin for 21 days. Then, each treatment was withdrawn for 3 days, and mice were randomly challenged with S, E, M1, or M2. During the next 7 days, S and E groups were subjected to daily treatment with S, E, M1, or M2. On the eighth day, all rats were tested under ethanol challenge. The saline group expressed sensitization under ethanol challenge similarly to the ethanol group. Mianserin+ethanol blocked the development of sensitization, suggesting an involvement of the 5-HT(2C) receptor subtype on ethanol-induced sensitization. Ethanol challenge to the chronic mianserin group did not express sensitization, implicating a role for mianserin in protection against stress. Mianserin did not reverse established ethanol sensitization, suggesting that cocaine- and ethanol-induced sensitization involved different mechanisms.
Asunto(s)
Conducta Animal/efectos de los fármacos , Depresores del Sistema Nervioso Central/farmacología , Etanol/farmacología , Receptores de Serotonina/efectos de los fármacos , Antagonistas de la Serotonina/farmacología , Animales , Masculino , Mianserina/farmacología , Ratones , Actividad Motora/efectos de los fármacos , Receptor de Serotonina 5-HT2C/efectos de los fármacosRESUMEN
The serotonergic system is involved in depression, anxiety and alcoholism. The rewarding properties of ethanol, mainly its anxiolytic and stimulant effects, as well as the development of dependence on ethanol have been related to the serotonergic system. Consequently, the use of selective serotonergic reuptake inhibitors (SSRI) has been proposed in the treatment of alcoholism. In this study we investigated whether acute administration of the SSRIs fluoxetine or paroxetine is able to (i) reverse the behavioral effects induced by chronic ethanol consumption, and conversely, (ii) to determine whether acute ethanol is able to substitute for the chronically induced behavioral effects of fluoxetine or paroxetine. Four groups of male Swiss mice (n=60/group) received daily i.p. saline, ethanol (2 g/kg), fluoxetine (10 mg/kg) or paroxetine (5 mg/kg) for 27 days. On the 28th day, each group was challenged with saline, ethanol, fluoxetine or paroxetine. The 14 groups (SS, SE, SP, SF, EE, ES, EP, EF, PP, PE, PS, FF, FE, and FS) were then tested in open field, activity cage and plus-maze. EP and EF groups were able to reverse the behavioral sensitization to the psychomotor stimulant effects of chronic ethanol administration. In contrast, a sensitized stimulatory effect was observed in chronically fluoxetine- or paroxetine treated mice challenged with ethanol (PE and FE). An anxiolytic effect was observed whether ethanol was substituted for SSRI or, conversely, SSRI was substituted for ethanol. SSRIs facilitated ethanol-induced locomotor sensitization, although SSRIs by themselves are unable to produce the locomotor stimulation similar to that induced by ethanol. Finally, SSRIs are unable to interfere in the ethanol anxiolytic effect.
Asunto(s)
Antidepresivos de Segunda Generación/farmacología , Conducta Animal/efectos de los fármacos , Depresores del Sistema Nervioso Central/farmacología , Etanol/farmacología , Fluoxetina/farmacología , Paroxetina/farmacología , Animales , Ansiedad/psicología , Conducta Exploratoria/efectos de los fármacos , Miedo/efectos de los fármacos , Miedo/psicología , Masculino , Ratones , Actividad Motora/efectos de los fármacosRESUMEN
The responses of mice to low doses of acutely and chronically administered ethanol (2.0 g/kg) and diazepam (2.0 mg/kg) were observed in activity cages, the open field and the elevated plus-maze. After prolonged administration, ethanol significantly increased locomotion in the activity cages and the plus-maze. In the open field, an increase was only observed in the tests performed after 7 and 14 days of treatment. Ethanol increased the open-arm time in the plus-maze in all the tests, including after acute administration, suggesting an anxiolytic effect. Diazepam induced an anxiolytic effect after 14 days of daily injections but had no stimulant effect on locomotion. Moreover, after prolonged administration sensitization to the anxiolytic, but not to the stimulant effect, was observed. In short, the present paper's data support the hypothesis that the stimulant and anxiolytic effects of ethanol are probably being mediated by distinct mechanisms. Furthermore, these data support the hypothesis that drugs that lead to abusive use, such as ethanol, may act both as positive and negative reinforcement.