A considerable amount experimental studies have shown that maternal separation (MS) is associated with adult offspring abnormal behavior and cognition disorder. Accordingly, this experimental procedure has been proposed as a predictor for alcohol and drug dependence based on the neurodevelopmental soon after birth. Endocannabinoid system (eCBs) has been implicated in reward processes, including drug abuse and dependence. MS and associated stress causes changes in the eCBs that seem to facilitate alcohol consumption. In this study, we seek to evaluate potential morphological changes in neurons of the frontal cortex (FCx) and nucleus accumbens (NAcc), in the expression of receptors and enzymes of the endocannabinoid and dopamine systems and in second messengers, such as Akt, in adult rats subjected to MS and early stress (MS + ES; 2 × 180 min daily) vs. nonseparated rats (NMS). Results showed that MS + ES induces higher D2R expression and lower D3R, FAAH, and MAGL expression compared with NMS rats. Alterations in total dendritic length were also detected and were characterized by increases in the NAcc while there were decreases in the FCx. We believe MS + ES-induced changes in the dopaminergic and endocannabinergic systems and in the neuronal microstructure might be contributing to alcohol seeking behavior and, potential vulnerability to other drugs in rats. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 819-831, 2016.

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Previous experiments have demonstrated that auditory (AS) and/or somatosensory (SS) stimulation can increase the duration of REM sleep periods in rats, cats and humans. The objectives of this study were to determine whether repeated AS stimulation causes habituation to the stimulus and whether any additive effects could be obtained with the simultaneous application of AS and SS. Three experimental procedures were used in this study. In experiment 1, animals were recorded for 4 consecutive days with AS, followed by a post-stimulus session. In experiment 2, they were recorded for 24 hours with AS applied at each REM period, followed by a subsequent 24-hours-post-stimulus recording. In experiment 3, animals underwent AS, SS stimulation, or simultaneous application of both in a random fashion at each REM period. The results of all experiments confirm previous findings showing that auditory or somatosensory stimuli significantly increase REM sleep period duration. In addition, AS--applied with different presentations during REM and throughout the sleep-wake cycle--are capable of increasing REM duration regardless of the manner in which they were presented. However, the effects of the stimuli were not additive. It is worth noting that although REM duration increased, REM period frequency decreased, resulting in no net change of total REM sleep through time. Furthermore, no changes were observed in other sleep-wake variables. These experiments clearly demonstrate that repeated auditory stimulation does not cause habituation, and there are no evident side effects on the sleep-wake cycle. These results confirm that the mechanisms involved in REM generation and maintenance can be modulated by sensory modalities.

En su Tractatus Theológico-Politicus, Baruch Spinoza escribió que “es una ley universal de la naturaleza humana que nadie rechaza lo que considera bueno excepto por la esperanza de un bien mayor o el miedo a una gran pérdida, y que nadie soporta ningún mal excepto para evitar un mal mayor u obtener un gran bien”. En otras palabras, para Spinoza existían dos fuerzas fundamentales que dirigían la conducta humana: la búsqueda de recompensas y la evasión del castigo. En las neurociencias, una recompensa puede definirse como aquel estímulo que se traduce en sentimiento de placer, excitación y gozo; es el componente principal del aprendizaje basado en incentivos y la realización de conductas dirigidas y consumatorias. Históricamente, las recompensas le han permitido al humano sobrevivir al conservar aquellas conductas que facilitan la obtención de alimento, agua, compañía, sexo y descendencia. No obstante, al mismo tiempo han influido en el desarrollo de conductas nocivas como la compulsión y el abuso de sustancias. Una de las principales metas de la investigación neurobiológica es entender los cambios a nivel molecular, celular y de circuitos que medían la transición del uso ocasional y controlado de dichas sustancias a la pérdida de control en el consumo y la adicción. En este trabajo se explicarán las bases neurobiológicas que subyacen en la transición entre en el placer y la compulsión. Posteriormente, se relacionará la influencia de la reducción de horas de sueño como factor de riesgo en el aumento en el consumo de drogas y alimentos palatables así como las bases biológicas de esta interacción.

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