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Updated: Jul 5, 2026
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Intradermal Microdialysis: An Approach to Investigating Novel Mechanisms of Microvascular Dysfunction in Humans
Published on: July 21, 2023
Central pathway for spontaneous and prostaglandin E2-evoked cutaneous vasoconstriction
Joseph A Rathner1, Christopher J Madden, Shaun F Morrison
1Neurological Sciences Institute, Oregon Health and Science University, Beaverton, Oregon, USA.
Summary
Fever increases body temperature by reducing heat loss. Prostaglandin E2 in the preoptic area activates cutaneous vasoconstrictor sympathetic outflow, but this pathway does not require the dorsomedial hypothalamus.
Area of Science:
- Neuroscience
- Physiology
- Thermoregulation
Background:
- Elevated body temperature during fever is partly due to reduced heat loss via increased cutaneous vasoconstrictor (CVC) sympathetic outflow.
- The dorsomedial hypothalamus (DMH) and preoptic area (POA) are key brain regions involved in thermoregulation.
Purpose of the Study:
- To determine the role of dorsomedial hypothalamus (DMH) neurons in mediating increases in CVC sympathetic tone evoked by prostaglandin E2 (PGE2) in the preoptic area (POA).
- To elucidate the neural pathways involved in fever-induced changes in sympathetic outflow.
Main Methods:
- Experiments were conducted in chloralose/urethane-anesthetized rats.
- Neuronal activity was recorded from CVC sympathetic ganglion cells innervating the tail artery.
- Pharmacological manipulations included nanoinjections of bicuculline and muscimol into the DMH and POA, and transections of the neuraxis.
Main Results:
- Bicuculline injection into the DMH increased CVC sympathetic nerve activity, as did PGE2 injection into the POA.
- Inhibition of DMH neurons with muscimol did not affect PGE2-evoked CVC activity, indicating DMH activation is not necessary.
- Inhibition of rostral raphé pallidus (rRPa) neurons reduced, but did not abolish, PGE2-evoked CVC activity, suggesting a parallel pathway.
Conclusions:
- Activation of DMH neurons is sufficient, but not necessary, for PGE2-evoked increases in CVC sympathetic nerve activity.
- The PGE2-evoked CVC response in the POA involves relief of tonic inhibition on CVC sympathetic premotor neurons in the rRPa.
- This response is dependent on excitation of CVC premotor neurons from a site caudal to the DMH, independent of DMH involvement.
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