Tag: heat sensitivity

A Woman With Multiple Neuropathic Symptoms, Hypersensitivity to Heat, Peppers, and Alcohol, With a Variant in the TRPV1 Capsaicin Receptor Gene: Possible Implications to ME/CFS

Abstract:

Transient receptor potential vanilloid 1 (TRPV1) is a ligand and heat-gated ion channel expressed on nociceptors that plays a central role in thermal and chemical pain signaling. Loss-of-function variants in TRPV1 have been associated with reduced nociception. We report a 65-year-old woman with disabling polyneurofunctional/neuropathic symptomatology including migraine, functional gastrointestinal disorders, and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS).

Diagnostic evaluation revealed sensory polyneuropathy and autonomic instability. Whole genome sequencing reanalysis identified a heterozygous TRPV1 c.2174A > T (p.Lys725Met) Likely Pathogenic variant that is very rare and highly conserved.

Our patient reports consistent, longstanding, marked hypersensitivity to heat, capsaicin, and alcohol, all of which are known TRPV1 agonists, supporting a gain-of-function mechanism for this variant. Furthermore, prior studies have implicated TRPV1 hyperactivity in migraine, nociceptive sensitization, and ME/CFS. Despite the excellent clinical correlation, causality of the variant cannot be definitively established without functional studies.

This case expands the potential phenotypic spectrum associated with TRPV1, and highlights a possible role for TRPV1-mediated channelopathies in complex neurofunctional disorders including ME/CFS.

Source: Zimmermann PM, Boles RG. A Woman With Multiple Neuropathic Symptoms, Hypersensitivity to Heat, Peppers, and Alcohol, With a Variant in the TRPV1 Capsaicin Receptor Gene: Possible Implications to ME/CFS. Case Rep Genet. 2026 Nov 3;2026:1920171. doi: 10.1155/crig/1920171. PMID: 42979319; PMCID: PMC13729082. https://pmc.ncbi.nlm.nih.gov/articles/PMC13729082/ (Full text)

Modulation of the axon-reflex response to local heat by reactive oxygen species in subjects with chronic fatigue syndrome

Abstract:

Local cutaneous heating causes vasodilation as an initial first peak, a nadir, and increase to plateau. Reactive oxygen species (ROS) modulate the heat plateau in healthy controls. The initial peak, due to C-fiber nociceptor-mediated axon reflexes, is blunted with local anesthetics and may serve as a surrogate for the cutaneous response to peripheral heat. Chronic fatigue syndrome (CFS) subjects report increased perception of pain. To determine the role of ROS in this neurally mediated response, we evaluated changes in cutaneous blood flow from local heat in nine CFS subjects (16-22 yr) compared with eight healthy controls (18-26 yr).

We heated skin to 42°C and measured local blood flow as a percentage of maximum cutaneous vascular conductance (%CVC(max)). Although CFS subjects had significantly lower baseline flow [8.75 ± 0.56 vs. 12.27 ± 1.07 (%CVC(max), CFS vs. control)], there were no differences between groups to local heat. We then remeasured this with apocynin to inhibit NADPH oxidase, allopurinol to inhibit xanthine oxidase, tempol to inhibit superoxide, and ebselen to reduce H(2)O(2). Apocynin significantly increased baseline blood flow (before heat, 14.91 ± 2.21 vs. 8.75 ± 1.66) and the first heat peak (69.33 ± 3.36 vs. 59.75 ± 2.75). Allopurinol and ebselen only enhanced the first heat peaks (71.55 ± 2.48 vs. 61.72 ± 2.01 and 76.55 ± 5.21 vs. 58.56 ± 3.66, respectively). Tempol had no effect on local heating. None of these agents changed the response to local heat in control subjects. Thus the response to heat may be altered by local levels of ROS, particularly H(2)O(2) in CFS subjects, and may be related to their hyperesthesia/hyperalgesia.

 

Source: Medow MS, Aggarwal A, Baugham I, Messer Z, Stewart JM. Modulation of the axon-reflex response to local heat by reactive oxygen species in subjects with chronic fatigue syndrome. J Appl Physiol (1985). 2013 Jan 1;114(1):45-51. doi: 10.1152/japplphysiol.00821.2012. Epub 2012 Nov 8. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3544512/ (Full article)