Monoamines (serotonin, dopamine, norepinephrine) in the brain are neurotransmitters used by a small number of specialized neurons and are responsible for the regulation of emotions and behavior.Currently, drugs that regulate the amount of monoamines in the brain are indispensable for the treatment of depression and attention deficit / hyperactivity disorder (ADHD).However, until now, there have been many unclear points about monoamines, such as the site existing in the brain, its amount, or the mechanism of action.

　The research group has long been developing "mass spectrometry imaging" that can investigate the distribution of various molecules using mass spectrometry.This time, we applied an analysis method called the "internal standard method" that can reduce the variation in measured values.As a result, we constructed a highly accurate analytical method that can compare a large number of measurement results, and performed monoamine mapping of the entire mouse brain.

　Multiple monoamine-accumulated nuclei were newly identified from the prepared monoamine whole-brain map.Among them, it was found that an extremely large amount of serotonin and norepinephrine are accumulated in the nucleus called "paraventricular nucleus", which is deeply involved in emotional regulation such as fear and anxiety, and this nucleus is important to connect the serotonin nervous system and the norepinephrine nervous system. It was suggested that it was a nerve nucleus.

　There are various techniques for acquiring brain images, but this is the first example of whole-brain mapping using a method that directly detects monoamines.The new serotonin neural circuit including the paraventricular nucleus of the thalamus discovered this time is expected to be a new drug discovery target for the development of new therapeutic agents for psychiatric disorders.

Paper information:[IScience] Detection of a high turnover serotonin circuit in the mouse brain using massspectrometry imaging