Oral histidine intake improves working memory through the activation of histaminergic nervous system in mice.

Histamine is synthesised from l-histidine through the catalysis of histidine decarboxylase (HDC). In the central nervous system (CNS), histamine is exclusively produced in histaminergic neurons located in the posterior hypothalamus and controls various CNS functions. Although histidine was known as a precursor of histamine, the impact of oral histidine intake on brain histamine concentration and brain function has not been fully elucidated.