Warm- and cold-sensitive neurons inactive at normal core temperature in rat hypothalamic slices

Area of Science:

• Neuroscience
• Physiology
• Thermoregulation

Background:

• The preoptic area and anterior hypothalamus are critical brain regions for thermoregulation.
• Understanding the specific roles of thermosensitive neurons is essential for comprehending body temperature control.

Purpose of the Study:

• To investigate the electrical activity and temperature sensitivity of neurons in the rat preoptic area and anterior hypothalamus.
• To characterize the properties of warm- and cold-sensitive neurons and their potential roles in thermoregulation.

Main Methods:

• Extracellular recordings of neuronal electrical activity were performed on brain slices.
• Neurons were analyzed for spontaneous firing rates across different temperature ranges (32-36°C and 37-40°C).

Main Results:

• At high temperatures (37-40°C), 33% of neurons were warm-sensitive, 8% cold-sensitive, and 59% thermally insensitive.
• At low temperatures (32-36°C), 8% were warm-sensitive, 29% cold-sensitive, and 63% thermally insensitive.
• Specific populations of warm- and cold-sensitive neurons exhibited threshold responses, hysteresis, and transient responses to temperature changes, suggesting a thermostat-like function.

Conclusions:

• Thermosensitive neurons in the rat preoptic area and anterior hypothalamus function as thermostats, actively regulating brain temperature.
• These neurons exhibit distinct sensitivities and response patterns, enabling both narrow and wide band control of body temperature.
• The findings suggest these neurons are integral components of the brain's thermoregulatory system, acting as regulators rather than mere sensors.