The effects of intermittent exposure to ethanol during adolescence are evident in adulthood, during which greater sensitivity and intake of cocaine is observed and differ in each sex.
Novelty seeking (NS), defined as a tendency to pursue novel and intense emotional sensations and experiences, is one of the most relevant individual factors predicting drug use among humans. High novelty seeking (HNS) individuals present an increased risk of drug use compared to low novelty seekers. The NS endophenotype may explain some of the differences observed among individuals exposed to drugs of abuse in adolescence. However, there is little research about the particular response of adolescents to drugs of abuse in function of this endophenotype, and the data that do exist are inconclusive. The present work reviews the literature regarding the influence of NS on psychostimulant reward, with particular focus on adolescent subjects. First, the different animal models of NS and the importance of this endophenotype in adolescence are discussed. Later, studies that have used the most common animal models of reward (self-administration, conditioned place preference paradigms) to evaluate how the NS trait influences the rewarding effects of psychostimulants are reviewed. Finally, possible explanations for the enhanced risk of developing substance dependence among HNS individuals are discussed. In conclusion, the studies referred to in this review show that the HNS trait is associated with: (1) increased initial sensitivity to the rewarding effects of psychostimulants, (2) a higher level of drug craving when the subject is exposed to the environmental cues associated with the drug, and (3) enhanced long-term vulnerability to relapse to drug consumption after prolonged abstinence.
Low-PPI mice presented a lower sensitivity to the conditioned rewarding effects of cocaine, but once they were conditioned with a higher dose, they displayed a stronger, perseverant conditioned preference. The predictive capacity of PPI to detect the more vulnerable mice to the conditioned effects of cocaine is discussed.
Introducción. La inhibición por prepulso (IPP) de la respuesta de sobresalto es una medida de sincronización sensitivomotora basada en la respuesta del reflejo de sobresalto. Un déficit en la IPP se ha observado en pacientes psiquiátricos, especialmente con esquizofrenia, así como en sujetos vulnerables a desarrollarla. Asimismo, los consumidores de cocaína presentan un alto índice de patologías psiquiátricas como la esquizofrenia. Objetivo. Conocer las alteraciones que el consumo de cocaína puede producir en la IPP. Desarrollo. Se realiza una revisión exhaustiva de los estudios, tanto clínicos como con modelos animales, que hayan evaluado la IPP tras el consumo o la administración de cocaína. Se sugieren bases neurales y mecanismos de acción subyacentes para explicar los resultados. Conclusiones. La cocaína altera la IPP a través de su acción sobre el sistema dopaminérgico. La administración aguda de cocaína disminuye la IPP al aumentar la dopamina, mientras que con el consumo crónico, dependiendo del tiempo de abstinencia, la IPP puede restablecerse. Sin embargo, los efectos de la cocaína sobre la IPP parecen depender de los niveles basales de la IPP que muestre el individuo. Así, dado que un déficit en la IPP se ha relacionado con una mayor vulnerabilidad a desarrollar patologías mentales como la esquizofrenia, los niveles de la IPP en los sujetos podrían considerarse como un biomarcador de vulnerabilidad psiquiátrica. Por ello, conocer mejor el efecto que drogas como la cocaína ejercen sobre la IPP puede ayudar a comprender el desarrollo de la patología dual. Palabras clave. Cocaína. Dopamina. Inhibición por prepulso. Trastornos psiquiátricos.
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