So far, understanding and recreating animal torpor has proven difficult. However, researchers from the Shenzhen Institute of Advanced Technology (SIAT) in China have found a way to chemically trigger a state of hypothermia in monkeys. This resulted in reduced body temperature and lower energy requirements.
The team targeted a part of the hypothalamus known as the preoptic area (POA), which is considered to control thermoregulation. They did this by using a synthetic drug and a brain scan.
Illustration of how preoptic neurons drive hypothermia
“To investigate the brain-wide network as a consequence of preoptic area (POA) activation, we performed fMRI scans and identified multiple regions involved in thermoregulation and interoception. This is the first fMRI study to investigate the brain-wide functional connections revealed by chemogenetic activation,” said Dai ji says, neuroscientist and author of the study.
The team first infected the POA’s neurons with viruses that cause receptors to respond. When researchers administrated the synthetic drug Clozapine N-oxide, they found that it reliably triggered hypothermia (lower body temperature) in anesthetized and awake monkeys.
In the anesthetized experiments, surprisingly, CNO-induced neuronal activity induced a decrease in core body temperature, preventing external heating. According to researchers, this demonstrates the critical role POA neurons play in primate thermoregulation.
The researchers also looked at how the monkeys’ bodies and behaviors changed when their body temperature was lowered. Similar experiments on mice and rats resulted in decreased activity and lower heart rates in an attempt to conserve heat. By contrast, the monkeys kept moving around, their hearts were beating much faster, and they were shivering – all in an effort to combat the falling body temperature.