Effects of systemic oxytocin administration on ultraviolet B-induced nociceptive hypersensitivity and tactile hyposensitivity in mice

• Published in: Molecular pain Vol. 20; p. 17448069241226553
• Main Authors: Boada, M Danilo, Gutierrez, Silvia, Eisenach, James C
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA SAGE Publications 01.01.2024; Sage Publications Ltd
• Subjects: Animals; Electrical properties; Hormones; Hypersensitivity; Male; Mechanical properties; Mechanoreceptors; Metastases; Mice; Mice, Inbred C57BL; Nerve conduction; Nociception; Nociceptors; Nociceptors - physiology; Oxytocin; Oxytocin - pharmacology; Oxytocin - therapeutic use; Pain perception; Peripheral nerves; Radiation; Receptor mechanisms; Skin - innervation; Touch - physiology; Ultraviolet radiation; Nociception; oxytocin; pain; ultraviolet B radiation; sensitization
• DOI: 10.1177/17448069241226553
• ISSN: 1744-8069

Ultraviolet B (UVB) radiation induces cutaneous inflammation, leading to thermal and mechanical hypersensitivity. Here, we examine the mechanical properties and profile of tactile and nociceptive peripheral afferents functionally disrupted by this injury and the role of oxytocin (OXT) as a modulator of this disruption. We recorded intracellularly from L4 afferents innervating the irradiated area (5.1 J/cm2) in 4-6 old week male mice (C57BL/6J) after administering OXT intraperitoneally, 6 mg/Kg. The distribution of recorded neurons was shifted by UVB radiation to a pattern observed after acute and chronic injuries and reduced mechanical thresholds of A and C- high threshold mechanoreceptors while reducing tactile sensitivity. UVB radiation did not change somatic membrane electrical properties or fiber conduction velocity. OXT systemic administration rapidly reversed these peripheral changes toward normal in both low and high-threshold mechanoreceptors and shifted recorded neuron distribution toward normal. OXT and V1aR receptors were present on the terminals of myelinated and unmyelinated afferents innervating the skin. We conclude that UVB radiation, similar to local tissue surgical injury, cancer metastasis, and peripheral nerve injury, alters the distribution of low and high threshold mechanoreceptors afferents and sensitizes nociceptors while desensitizing tactile units. Acute systemic OXT administration partially returns all of those effects to normal.