Neuron: Unlike you think, scientists reveal the neural circuits that regulate body temperature behavior

Click on the blue word to focus on the ability of our mammals to maintain body temperature fluctuations within a small range for survival
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Different from the autonomic nervous response of trembling thermogenesis, the thermoregulation behavior is a motivated, goal-oriented behavior that is flexible in various forms, which saves energy
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The paraspinal pathway projected to the lateral parabrachial nucleus (LPB) is essential for autonomic nerves and behavioral thermoregulatory responses, and is also a key brain area for avoiding high fever and cold behavior
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On October 21, 2021, the Sung-Yon Kim research team of Seoul National University in South Korea revealed the body's mechanism to regulate body temperature and maintain a stable neural circuit
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Inhibition of LH-Vgat neurons shows obstacles in thermoregulatory behavior.
In the self-heating task, mice in cold ambient temperature will turn on the infrared (IR) heating lamp by touching the nose for 2 seconds to warm up
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However, after inhibiting the inhibitory neurons of the lateral thalamus (LH-Vgat neurons), the mice's thermoregulatory behavior became obstructed
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The calcium imaging system records the activity of LH-Vgat neurons.
The optical fiber calcium imaging system found that the LH-Vgat neurons were activated in large numbers during the nasal contact behavior of mice, and the activity decreased rapidly after being heated by infrared light
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During the ad libitum intake of sucrose, LH-Vgat neurons are activated in large numbers
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These results indicate that LH-Vgat neurons are activated in thermoregulatory behavior and calorie expenditure reward behavior, but inhibited in thermal reward effect
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In the instinctive thermoregulation experiment, after chronically inhibiting the above types of neurons, the mice could not choose the best temperature position to avoid the high heat or cold environment
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Since inhibiting the inhibitory neurons of the lateral thalamus does not affect the brown adipose tissue heat production, these neurons are not so important for the thermoregulatory response of the body
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However, chronic activation of LH-Vgat neurons does not promote temperature regulation behavior, but promotes the biting behavior of mice
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Further through the optical fiber recording system, it is found that infrared heating at low temperature or cold stimulation at high temperature can inhibit the activity of LH-Vgat neurons, while infrared heating at high temperature or cold stimulation at low temperature can enhance the activity of LH-Vgat neurons
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This indicates that LH-Vgat neuron activity is inhibited under cold or heat reward, and the neuron is activated under cold or heat aversion
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Retrograde tracer virus found that LH-Vgat neurons received excitatory input from LPB
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Chronic inhibition of LPB neuron activity hinders self-heating tasks and also hinders the response process of LH-Vgat neurons to heat reward behavior, but it does not affect the eating behavior of mice, nor does it affect the eating behavior of LH-Vgat neurons.
Response
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After inhibiting the neural circuit of LPB-LH, the self-warming behavior of the mice became obstructed
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This indicates that the LPB brain area is only responsible for inputting thermoregulation information to the LH brain area, and does not interfere with the LH brain area's function of controlling eating
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Furthermore, two-photon microscopy single-cell calcium imaging technology found that the neuron subgroups encoding cold and heat reward and aversion behaviors in the LH brain region are completely different from the neuron subgroups encoding calorie heat reward behaviors, so precise regulation can be achieved
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In general, this article reveals that LH-Vgat neurons are the key loop hub of thermoregulatory behavior, directly accepting excitatory input from LPB to achieve purposeful thermoregulatory behavior
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[References] 1.
https://doi.
org/10.
1016/j.
neuron.
2021.
09.
039 The pictures in the text are from the references