[The Importance of Vagus Nerve Afferent in the Formation of Emotions in Attention-Deficit Hyperactivity Disorder Model Rat].

It is of interest to know how environmental stimuli contribute to the formation of emotion during development. In a rat model of attention-deficit hyperactivity disorder, monosodium L- glutamate (MSG), a taste substance of umami, was administered for 5 weeks during developmental period, followed by emotional behavior tests such as open-field test and social interaction test in adulthood. Although no significant change was observed in anxiety-like behavior, MSG intake caused a reduction in aggressive behavior. Vagotomy under the level of diaphragm resulted in eliminating the MSG effect on aggression, indicating the importance of neuronal activity of the vagus nerve in this effect. Futher studies will focus on futher questions regarding the gut-brain axis such as the change of microbiota and the mechanism of the axis in the brain.