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Preoptic mechanism for cold-defensive responses to skin cooling
Kazuhiro Nakamura1, Shaun F Morrison
1Neurological Sciences Institute, Oregon Health and Science University, 505 NW 185th Avenue, Beaverton, OR 97006, USA. nakamura@ohsu.edu.
The Journal of Physiology
|April 5, 2008
Summary
This study reveals how skin cooling activates neurons in the median preoptic nucleus (MnPO) to inhibit thermoregulatory output neurons. This GABAergic mechanism is crucial for defending body temperature against cold.
Area of Science:
- Neuroscience
- Physiology
- Thermoregulation
Background:
- A somatosensory pathway transmitting skin temperature to the preoptic area (POA) was previously identified.
- The POA is a key thermoregulatory center in the brain.
Purpose of the Study:
- To investigate the in vivo neuronal circuit within the rat POA that processes thermosensory information.
- To understand how this circuit generates thermoregulatory effector signals.
Main Methods:
- In vivo electrophysiological recordings and neuronal inhibition/stimulation in rats.
- Pharmacological manipulation of GABA(A) receptors in the medial preoptic area (MPO).
Main Results:
- Inhibition of median preoptic nucleus (MnPO) neurons reversed cold-induced increases in sympathetic thermogenesis, metabolism, and heart rate.
- Glutamatergic stimulation or disinhibition of MnPO neurons mimicked cold-defensive responses.
- These mimicked responses were blocked by antagonizing GABA(A) receptors in the MPO.
Conclusions:
- GABA inhibition of MPO output neurons by MnPO neurons activated by cool skin signals is a core POA thermoregulatory mechanism.
- This feedforward mechanism is essential for defending body temperature against environmental cold challenges.
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