Researchers at Nagoya University (Japan) have discovered that EP3 neurons (in the preoptic area of the brain) are key to regulating body temperature in mammals, a finding that could help treat disorders such as heat stroke or hypothermia.
The discovery, published in Science Advances, could be used to develop a technology to artificially regulate body temperature which is altered in certain pathologies and even in obesity.
In humans and many mammals, body temperature hovers around 37°C, allowing for all regulatory functions, but when temperatures deviate significantly from the normal range, functions are impaired, causing heat stroke, hypothermia, and sometimes death. death.
But scientists believe these conditions could be treated if body temperature could be artificially regulated.
The temperature-regulating center resides in the preoptic area of the brain, the part of the hypothalamus that controls the body’s vital functions.
For example, when the preoptic area receives signals that there is an infection, this area issues an order to raise the body temperature (fever) and fight off viruses, bacteria and organisms that attack the body.
But it is not yet known exactly which neurons in the preoptic area issue orders to raise or lower body temperature.
To identify them, the researchers conducted a study in rats and focused on EP3 neurons in the preoptic area, which express PGE2 EP3 receptors.
They first investigated how the activity of EP3 neurons in the preoptic area varies in response to changes in ambient temperature.
Therefore, for two hours, they exposed the rats to cold (4°C), room (24°C) and warm (36°C) temperatures. The results showed that exposure to 36°C activated EP3 neurons, while exposure to 4°C and 24°C did not.
They then examined the nerve fibers of EP3 neurons in the preoptic area to identify where EP3 neuron signals are transmitted, and found that these fibers are distributed in different regions of the brain, especially the dorsomedial hypothalamus (DMH), which activates the sympathetic nervous system.
Their analysis also showed that the substance used by EP3 neurons for signaling to DMH is gamma-aminobutyric acid (GABA), an important inhibitor of neuronal excitation.
To further investigate the role of EP3 neurons in temperature regulation, they artificially manipulated their activity and found that their activation caused a drop in body temperature, while suppressing their activity caused a rise in temperature.
The study demonstrated 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.
“Parguably, EP3 neurons in the preoptic area can fine-tune signal intensity to regulate body temperature,” says Kazuhiro Nakamura, lead author of the study.
“For example, in a hot environment, the signals are increased to suppress sympathetic outflow, which causes increased blood flow to the skin to facilitate body heat radiation and thus prevent heat stroke. But, in a hot environment When it’s cold, the signals are reduced to activate sympathetic outputs, which promote heat production in brown adipose tissue and other organs to prevent hypothermia,” notes the researcher.
These discoveries could pave the way for the development of a technology to artificially regulate body temperature.
‘Furthermore, this technology could lead to new strategies for people’s survival in increasingly warming global environments, which are becoming a major global problem,’ the researchers conclude.