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Cold-activated raphé-spinal neurons in rats.
J A Rathner1, N C Owens, R M McAllen
1Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Victoria 3010, Australia.
The Journal of Physiology
|September 18, 2001
Summary
Researchers identified sympathetic premotor neurons in the rat brainstem that activate during cold exposure. These neurons may control essential thermoregulatory responses like vasoconstriction and heat production.
Area of Science:
- Neuroscience
- Physiology
Background:
- Sympathetic premotor neurons are crucial for regulating body temperature.
- Understanding these neurons' role in thermoregulation is vital for addressing temperature-related disorders.
Purpose of the Study:
- To identify and characterize sympathetic premotor neurons in the rat brainstem involved in thermoregulatory functions.
- To investigate the response of medullary raphé-spinal neurons to cooling stimuli.
Main Methods:
- Extracellular unit recordings were performed on urethane-anesthetized, paralyzed rats.
- Neurons were activated antidromically by stimulating the upper lumbar cord.
- Non-noxious cooling stimuli were applied to the trunk skin, and neuronal activity was recorded.
Main Results:
- Cooling increased the activity of 21 out of 76 studied raphé-spinal neurons, with responses graded to skin temperature.
- Some cold-activated neurons also responded to core temperature changes, while others did not.
- Cold-activated neurons were located in the raphé magnus and pallidus nuclei and exhibited varying conduction velocities.
Conclusions:
- Cold-activated raphé-spinal neurons likely form a premotor pathway for sympathetic cold defenses, including vasoconstriction and thermogenesis.
- A brainstem reflex, potentially modulated by core body temperature signals, may mediate autonomic responses to environmental cooling.