RESUMEN
OBJECTIVE: In general, it is known that repetitive regular stimuli induce tolerance and repetitive irregular stimuli induce sensitization. We sought to determine the dopamine response in the rat prefrontal cortex under the repetitive regular and repetitive irregular stimuli. METHODS: After giving irregular and regular electrical stimuli repetitively to rats, we measured the dopamine levels of prefrontal cortex. We compared these results with the dopamine levels of prefrontal cortex of rats which were given just one electrical stimulus. Samples were obtained using in vivo brain microdialysis. Dopamine levels in the samples were measured by high pressure liquid chromatography with electrochemical detection. RESULTS: 1) Dopamine levels of prefrontal cortex of both repetitive regular stimuli group and repetitive irregular stimuli group increased after electrical stimuli. 2) Dopamine levels of prefrontal cortex also significantly increased after just one electrical stimulus. 3) Among the repetitive regular stimuli group, repetitive irregular stimuli group and one stimulus group, the dopamine response was most significant in the repetitive irregular stimuli group. CONCLUSIONS: Repetitive irregular electrical stimuli induce sensitization of prefrontal cortex and repetitive regular electrical stimuli don't induce tolerance of prefrontal cortex.