Introduction

The response of cutaneous vasculature to thermal stimuli is a fundamental homeostatic function critical for mammalian survival. In the skin, local cold exposure typically triggers rapid vasoconstriction to minimize heat loss. Although this response is generally attributed to centrally coordinated sympathetic reflexes, local neurovascular mechanisms may also contribute to cold-induced vascular control. In this context the transient receptor potential (TRP) channels, TRPA1 and TRPM8, have been identified as key molecular sensors in this complex vascular response, acting through both perivascular sensory and sympathetic nerve fibers (1, 2). Here, we tested the hypothesis that TRPM8 and TRPA1 mediate an intrinsic cold response in peripheral cutaneous arteries, independently of central nervous system reflexes.

Material and Methods

All animal procedures complied with European Directive 2010/63/EU and were approved by the relevant institutional ethics committees. We performed pressure myography experiments in isolated plantar arteries from C57BL/6J, Trpa1 and Trpm8 KO mice to determine changes in diameter upon exposure to low temperature. Pharmacological experiments included TRPA1 blockade (HC030031), CGRP receptor inhibition (BIBN 4096) and sympathetic blockade (Guanethidine). TRPA1 and TRPM8 mRNA expression was assessed by qPCR in vascular and sympathetic preparations, and confocal microscopy was used to examine TRPM8 localization in perivascular fibers labelled for sensory (anti-CGRP) and sympathetic (anti-Tyrosine Hydroxylase) markers.

Results

Our findings reveal that cold (15°C) induces a significant intrinsic contraction in isolated plantar arteries (28 ± 3.5%, n=11), whereas mesenteric arteries showed no reaction. This vasoconstriction was significantly attenuated in plantar arteries from Trpa1 KO (11.04 ± 2.5%, n=9) and Trpm8 KO mice (10.9 ± 1.9%, n=6) and fully abolished by simultaneous blockade of both channels. The response was unchanged in plantar arteries from Tpv4 KO and Trpm3 KO mice. In the presence BIBN (blockade of sensory fibers), the cold-induced vasoconstriction response was potentiated (39.2 + 5.5%, n=6) while sympathetic fiber blockade led to a cold-induced vasodilation (13.6 + 4.3%, n=5). TRPA1 and TRPM8 channels mRNA were detected in sympathetic ganglia, and confocal images of plantar arteries confirmed Trpm8 presence in perivascular sympathetic fibers.

Conclusions

Our results support that Isolated plantar arteries display an intrinsic vasomotor response to local cooling, mediated by TRPM8 and TRPA1 channels present in both sympathetic and sensory perivascular nerves. The net vasoconstrictor response observed is predominantly driven by activation of sympathetic perivascular fibers. These channels may represent promising targets for cold-dependent peripheral vascular disorders, such as Raynaud’s disease.