Interactions on neurotransmitter systems in the reward pathways may explain the high frequency of combined use of alcohol and cigarettes in humans. In this study, we evaluated some behavioral and neurochemical changes promoted by chronic exposure to alcohol and cigarette smoke in rats. Adult rats were administered with 2 g/kg alcohol (v.o.) or/and inhaled the smoke from 6 cigarettes, twice/day, for 30 days. Behavioral tests were performed 3 h after the alcohol administration and 1 h after the last exposure to cigarette smoke in the morning. Cerebrospinal fluid was collected for glutamate determination and the hippocampus was dissected for GABAA and NMDA receptor subunits mRNA expression determination. Results showed that the combined use of alcohol and cigarette smoke (ALTB) in rats increased the locomotor activity and all interventions decreased anxiety-like behaviors. Despite being on a short-term withdrawal, the cigarette smoke exposure decreased the percentage of open arm entries in the elevated plus maze test, which was prevented by combined use with alcohol. Even though GABAA and glutamate receptor subunits expression did not change in the hippocampus, glutamate levels were significantly higher in the cerebrospinal fluid from ALTB rats. Therefore, we showed that the combined use of alcohol and cigarette maintained a psychostimulant effect after a short-term withdrawal that was associated with the elevated glutamatergic activity. The combined use also prevented anxiety-like signs in cigarette smoke exposure rats, decreasing an adverse effect caused by nicotine withdrawal. These results could explain, in part, the elevated frequency of combined use of these two drugs of abuse in humans.

中文翻译：

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烟酒联合使用可增加脑脊液中的运动和谷氨酸水平，而不会改变大鼠海马中GABAA或NMDA受体亚基的mRNA表达。

奖励途径中神经递质系统的相互作用可能解释了酒精和香烟在人类中联合使用的频率很高。在这项研究中，我们评估了大鼠长期暴露于酒精和香烟烟雾引起的一些行为和神经化学变化。给成年大鼠服用2 g / kg酒精（vo）或/，并每天两次从6支香烟中吸入烟，持续30天。在饮酒后3小时和早晨最后一次接触香烟烟雾后1小时进行行为测试。收集脑脊液用于谷氨酸测定，并解剖海马用于GABAA和NMDA受体亚基mRNA表达测定。结果表明，酒精和香烟烟雾（ALTB）的联合使用可增加运动能力，所有干预措施均可降低焦虑样行为。尽管可以短期戒烟，但在高架迷宫测试中，暴露在香烟烟雾中却减少了张开双臂的百分比，这可以通过与酒精混合使用来避免。即使海马中的GABAA和谷氨酸受体亚基表达没有变化，来自ALTB大鼠的脑脊液中谷氨酸水平也明显更高。因此，我们表明，酒精和香烟的联合使用在短期戒断后与谷氨酸能活性升高有关，保持了精神刺激作用。联合使用还可以防止暴露在香烟烟雾中的大鼠出现焦虑样症​​状，减少因尼古丁戒断引起的不良影响。这些结果部分可以解释这两种滥用药物在人类中联合使用的频率增加。