Systemic inflammatory response syndrome (SIRS) is a potentially fatal reaction to various forms of tissue damage and infections that cause damage to various organs. Furthermore, the brain is damaged earlier than other organs, resulting in diffuse brain dysfunction. The central clinical symptom of SIRS is delirium and emotional changes are involved in disease development. Although the amygdala is known to play a major role, the mechanisms underlying emotional changes in the early stages of SIRS have not been elucidated. Therefore, changes to dopamine levels in the amygdala were observed using an in vivo model of lipopolysaccharide (LPS)- induced SIRS to clarify the biochemical mechanisms activated in the early stages of SIRS. Extracellular dopamine was collected from the amygdala of free moving rats via microdialysis and then analyzed by high-performance liquid chromatography. In addition, emotional changes were assessed with the open field and sucrose preference tests. In the LPS group, dopamine release in the amygdala increased remarkably immediately after LPS administration, peaking at 120 min. Thereafter, dopamine release temporarily decreased, but then significantly increased again after 180 min. The present results suggest that diffuse brain dysfunction in the early stages of SIRS may involve altered dopamine levels in the amygdala.

KEY WORDS: Dopamine; Amygdala; Rat; Systemic inflammatory response syndrome; Sepsis-associated encephalopathy.

YAKURA, T.; NAITO, M.; ICHIKAWA, T.; OSHIBUCHI, H.; YAMADA, M.; LI, Z. L.; KAWATA, S.; ITOH, M. Dopamine dynamics in the amygdala influence emotional changes in the early stage of systemic inflammatory response syndrome in rats. Int. J. Morphol., 42(2):332-340, 2024.