A Nagoya University research team found that a group of EP3 neurons play a crucial role in regulating mammalian body temperature. The findings published in the journal Science Advances could lead to the development of a device that adjusts body temperature artificially.
Body temperature in humans and many other mammals is regulated at around 37°C (98.6°F), which optimizes all regulatory functions. Each species is equipped with features that promote thermoregulation. Deviation from the normal body temperature range can result in impaired body regulation, which could lead to heat stroke, hypothermia or even death. These conditions can be minimized or avoided if body temperature can be artificially adjusted to the normal range.
The research team first investigated how ambient temperature changes impact the activity of EP3 neurons. The brain's temperature regulation center is located in the preoptic area, which is part of the hypothalamus that controls the body's vital functions. For two hours, the researchers exposed the rats to cold (4°C), room (24°C), and hot (36°C) temperatures (a comfortable environmental temperature for rats is around 28°C). Exposure to 36°C activated EP3 neurons, but exposure to 4°C and 24°C did not.
The researchers observed that nerve fibers are distributed to various brain regions, specifically to the dorsomedial hypothalamus (DMH) which activates the sympathetic nervous system. The researchers also discovered EP3 neurons use gamma-aminobutyric acid (GABA) to signal transmission to DMH.
Using a chemogenetic approach allowed the researchers to confirm that activating the neurons decreased body temperature, whereas suppressing neuronal activity increased temperature. Study author Dr. Cho elaborated on how the neurons affect regulation: "For example, in a hot environment, signals are augmented to suppress sympathetic outputs, resulting in increased blood flows in the skin to facilitate the radiation of the body’s heat to prevent heat stroke. However, in a cold environment, signals are reduced to activate sympathetic outputs, which promote heat production in brown adipose tissue and other organs to prevent hypothermia." This study showed that EP3 neurons in the preoptic area play a key role in regulating body temperature by releasing GABA to send inhibitory signals to DMH neurons to control sympathetic responses.
This study’s findings could pave the way for the development of a technology that artificially adjusts body temperature, which can be applied to a wide range of medical fields. Interestingly, this technology may be helpful in the treatment of obesity by keeping body temperature slightly higher than normal to promote fat burning.
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