When we are under stressful condition in daily life, we often feel emotional changes and physiological stress/emotional reaction such as a rapid heart rate, a pale skin, and an increase in body temperature known as emotional-hyperthermia or psychogenic fever. Our ultimate research goal is to elucidate brain mechanisms that process emotional changes. Emotional changes can be evaluated with verbal communication in human, but not in experimental animals. The physiological emotional reactions are observed in experimental animals such as mice, rats and rabbits. The pale skin is resulted from a decrease in blood flow to skin, and we have established technique to perform simultaneous measurement of skin blood flow, body and brown adipose tissue (BAT, major thermogenic tissue) and brain activity (electroencephalograph) in rats under free-moving condition. In our laboratory, we use resident-intruder stress test to cause emotional-hyperthermia and a pale skin in experimental animals, and measure physiological parameters including BAT temperature to evaluate emotional changes. We are currently investigating brain neural circuit underlying the link between stress and physiological changes, focusing on the orexin system and the serotonergic system. Recently we launched a new project targeting the habenula complex, which is a phylogenetically old brain region of the diencephalon.
Brain orexin and serotonergic systems are closely related to arousal and emotion that are strongly affected by a stressful event. In order to target these systems, we obtained several transgenic rats and mice from Prof Masashi Yanagisawa at the Southwestern Medical Center, University of Texas, and from Prof Akihiro Yamanaka at the Department of Neuroscience II, Nagoya University, Japan. We have setup the first breeding colony these rats and mice in Australia.
Our research takes modern genetic approach to incorporate optogenetics and pharmacogenetics including DREADDs (designer receptors exclusively activated by designer drugs) in-vivo study.