Scheggi S, Pelliccia T, Ferrari A, De Montis M G, Gambarana C
Department of Molecular and Developmental Medicine, University of Siena, Via Moro, 2, 53100 Siena, Italy.
Neuroscience. 2015 Apr 16;291:189-202. doi: 10.1016/j.neuroscience.2015.02.006. Epub 2015 Feb 14.
Anhedonia is a relevant symptom in depression and schizophrenia. Chronic stress exposure induces in rats escape deficit, disrupts the dopaminergic response to palatable food and the competence to acquire sucrose self-administration (SA), thus configuring a possible model of motivational anhedonia. Repeated lithium administration reverts stress effects and brings back to control values the breaking point (BP) score, a measure of reward motivation. In this study, we tested on this model two antidepressants, imipramine and fluoxetine, and two antipsychotics, haloperidol and clozapine. The dopaminergic response to sucrose consumption was studied in non food-deprived rats in terms of dopamine D1 receptor signaling in the nucleus accumbens shell (NAcS). More specifically, we studied the modifications in dopamine and cAMP-regulated phosphoprotein of Mr 32,000 (DARPP-32) phosphorylation pattern following sucrose consumption. Fluoxetine reverted the escape deficit and showed no effects on dopaminergic response and sucrose SA. Imipramine reverted sucrose SA and dopamine response deficit in half of the rats and the escape deficit in all animals. Haloperidol did not affect stress-induced deficits. Clozapine-treated rats recovered the dopaminergic response to sucrose consumption and the competence to acquire sucrose SA, although they still showed the escape deficit, thus confirming that motivation toward reward may be dissociated from that to punishment escape. These results indicate that imipramine or fluoxetine are not endowed with a rapid onset antianhedonic effect. On the other hand, clozapine treatment showed a motivational antianhedonic activity similar to that observed after lithium treatment.
快感缺失是抑郁症和精神分裂症中的一个相关症状。长期暴露于应激会导致大鼠出现逃避缺陷,破坏对美味食物的多巴胺能反应以及获得蔗糖自我给药(SA)的能力,从而构建出一种可能的动机性快感缺失模型。反复给予锂盐可逆转应激效应,并使断点(BP)评分恢复到对照值,BP评分是奖励动机的一种衡量指标。在本研究中,我们在该模型上测试了两种抗抑郁药,即丙咪嗪和氟西汀,以及两种抗精神病药,即氟哌啶醇和氯氮平。在未禁食的大鼠中,根据伏隔核壳(NAcS)中的多巴胺D1受体信号传导,研究了对蔗糖消耗的多巴胺能反应。更具体地说,我们研究了蔗糖消耗后多巴胺和32,000 Mr的多巴胺和cAMP调节磷蛋白(DARPP - 32)磷酸化模式的变化。氟西汀逆转了逃避缺陷,并且对多巴胺能反应和蔗糖SA没有影响。丙咪嗪在一半的大鼠中逆转了蔗糖SA和多巴胺反应缺陷,并在所有动物中逆转了逃避缺陷。氟哌啶醇不影响应激诱导的缺陷。氯氮平治疗的大鼠恢复了对蔗糖消耗的多巴胺能反应以及获得蔗糖SA的能力,尽管它们仍然表现出逃避缺陷,从而证实了对奖励的动机可能与逃避惩罚的动机相分离。这些结果表明,丙咪嗪或氟西汀不具有快速起效的抗快感缺失作用。另一方面,氯氮平治疗显示出与锂盐治疗后观察到的类似的动机性抗快感缺失活性。