Researchers Identify Neurons That Regulate Body Temperature

A research group led by Lecturer Yoshiko Nakamura and Professor Kazuhiro Nakamura, Department of Integrative Physiology, Nagoya University Graduate School of Medicine, Tokai National University, collaborated with Professor Hiroyuki Hioki, Department of Brain Circuit Morphology, Juntendo University Graduate School of Medicine. In rats, we identified a neuronal group that functions as a control center for thermoregulation.
The body temperature of most mammals, including humans, is strictly maintained at about 37°C, and if this regulation fails, all of the body’s regulating functions will be impaired, such as heatstroke and hypothermia, and in the worst case, death. increase. Therefore, elucidation of the basic mechanism that regulates body temperature is of great medical significance. However, although it was known that the thermoregulatory center was located in the preoptic area *1 in the hypothalamus of the brain, the neuronal group responsible for controlling thermoregulation was unknown. The research group focused on a group of neurons in the preoptic area (EP3 neurons *4 ) that express receptors for prostaglandin E2 *3
, which is a thermogenic mediator *2 , and EP3 receptors, and investigated its function in body temperature regulation. I checked. First, we found that exposure of a rat to heat (36°C) activated her EP3 neuron cluster in the preoptic area. On the other hand, when prostaglandin E2 was applied, the activation was suppressed, and at the same time, body temperature increased (fever). Furthermore, visualizing the nerve fibers extending from her EP3 neuron group in the preoptic area reveals that the dorsomedial hypothalamus involved in the control of the sympathetic nerves *5It was found that nerve transmission to His detailed analysis of more than 80,000 nerve endings in the EP3 neuron group extending from the preoptic area to the dorsomedial hypothalamus revealed that many of them were GABA (gamma-aminobutyric acid), an inhibitory neurotransmitter *6. was found to emit Selective activation of his EP3 neuron cluster in the preoptic area dilated cutaneous blood vessels *7 , causing active heat dissipation and a decrease in body temperature. On the other hand, selective inhibition of EP3 neuronal transmission from the preoptic area to the dorsomedial hypothalamus caused heat production in brown adipose tissue *8 , resulting in an increase in body temperature.
These experimental results suggest that EP3 neurons in the preoptic area are “master neurons” that control body temperature by constantly sending inhibitory signals to the sympathetic nervous system and changing the intensity of that inhibition. is shown. This research was carried out as part of the challenge to “elucidate the molecular and cellular mechanisms of the maintenance of biological homeostasis by inter-organ networks,” which is the core of Goal 2, a moonshot-type research and development project in which researchers are also participating. It is expected that this will lead to the elucidation of the whole picture of the neural circuit mechanism that controls metabolism and circulation in the future. In addition, it may lead to the development of new obesity treatment technology that promotes fat metabolism, and the development of diagnostic and preventive technology before the onset of diseases such as diabetes, for which abnormal fat metabolism is a risk factor (pre-disease stage). I have.
The results of this research were published in “Science Advances” (electronic version dated December 23, 2022).