Efecto de la cocaína sobre la inhibición por prepulso de la respuesta de sobresalto / Effects of cocaine on prepulse inhibition of the startle response

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 (AU)

Introduction. Prepulse inhibition (PPI) of the startle response is an index used to evaluate how the pre-attention system. works. PPI is altered in patients with a mental disorder such as schizophrenia and in subjects who are vulnerable to it. Likewise, cocaine users also frequently exhibit psychiatric disorders as schizophrenia. Aim. To know the alterations that cocaine produces on PPI. Development. A comprehensive review is carried out, covering both clinical and preclinical studies with animal models that have evaluated the effects of cocaine exposure on the PPI paradigm. Underlying neural bases and mechanisms of action are suggested to explain these findings. Conclusions. Cocaine alters PPI through its action on the dopaminergic system. Acute exposure of cocaine decreases PPI by increasing dopamine, while with chronic use, depending on withdrawal time, PPI can be restored. However, the effects of cocaine on PPI appear to depend on the baseline levels of PPI shown by the individual. Thus, since a deficit in PPI has been associated with a greater vulnerability to developing mental pathologies such as schizophrenia, PPI level in subjects could be considered as a biomarker of psychiatric vulnerability. Therefore, a better understanding of the effect of drugs such as cocaine on PPI may help to understand the development of dual pathology (AU)

Influence of the Novelty-Seeking Endophenotype on the Rewarding Effects of Psychostimulant Drugs in Animal Models.

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.

Influence of trait anxiety on the effects of acute stress on learning and retention of the passive avoidance task in male and female mice.

The influence of anxiety on the effects of acute stress for the acquisition and retention of passive avoidance conditioned task was evaluated in male and female mice. Animals were categorized as high-, medium-, and low-anxiety according to their performance in the elevated plus-maze test. Subsequently, half of the mice in each group were exposed to an acute stressor and assayed in an aversive conditioning test two days later. Exposure to restraint stress before inhibitory avoidance conditioning had a differential impact on the conditioned response of males and females according to their trait anxiety. The acute stressor significantly altered the conditioned response of mice with a high-anxiety level. The long-term effect of the stressor varied for each sex; high-anxiety stressed males showed an enhanced conditioned response with respect to their controls, whereas high-anxiety stressed females presented an impaired performance. These results lead us to believe that the characterization of individuality is an important factor in understanding the interaction between stress and memory for each sex; the trait anxiety of our animals modulated the effects of stress on the conditioned response so that males and females performed in contrasting manners to the same environmental stimuli and experimental conditions.