Mechanisms of cutaneous vasodilation during the postmenopausal hot flash.
Level 3 - non-randomized controlled study
Controlled human physiological mechanistic study with within-subject internal pharmacological control and direct neural recording.
PubMed 21107299 · doi:10.1097/gme.0b013e3181f7a17a
What was done
Healthy postmenopausal women were studied in a temperature-controlled laboratory across three experimental protocols to identify the neural mechanisms of cutaneous vasodilation during hot flashes. In protocols 1 and 2, laser-Doppler skin blood flow was measured during hot flashes at untreated control sites versus adjacent sites pretreated with intradermal botulinum toxin A (BTX, which inhibits sympathetic cholinergic neurotransmitter release) in the forearm and glabellar region, respectively. In protocol 3, peroneal skin sympathetic nerve activity was recorded directly alongside regional skin blood flow and sweating. Hot flash onset was objectively verified by transient rises in sternal sweat rate.
What was found
Skin blood flow increases during hot flashes were significantly attenuated at BTX-pretreated sites compared with untreated adjacent control sites in both the forearm (protocol 1) and glabellar region (protocol 2) (P < 0.05 for both). Protocol 3 demonstrated a significant increase in skin sympathetic nerve activity during hot flashes that resolved to pre-flash levels afterward. Specific numerical values and baseline blood flow metrics were not reported in the abstract.
Why it matters
This study provides direct neurophysiological evidence that cutaneous flushing during postmenopausal hot flashes is actively mediated by botulinum toxin-sensitive sympathetic cholinergic nerves.
Limits
The abstract does not state the sample size (n) or specific quantitative flow values and confidence intervals. Findings are derived from an artificial laboratory setting and focus exclusively on regional sympathetic cholinergic pathways without evaluating non-cholinergic co-transmitters.
Cited by
- contradicts Vasomotor hot flashes represent bodywide vascular spasms.