Why pigs? Spontaneous pain and hyperalgesia as a result of inflammation and tissue damage are commonly studied in rodents as animal models for humans. However, these species show limited resemblance in the anatomical structure and in the functioning of nerve fibers and receptors. Pigs are considered highly relevant due to their greater anatomical homology, and are used increasingly as animal model species. Porcine skin is comparable to human. Recently laser thermal stimulation has been validated as a new tool for measuring pain threshold; increased flare reaction in inflamed skin and the confirmation of striking similarities in functional properties of cutaneous C-fibers in pigs and humans through single-fiber neurography. Aim This project is developed in order to establish a new animal model of translational research and provide information on cutaneous inflammatory pain that can apply to human medical conditions. Methods Induction: 3 models of local inflammation with different mechanisms of action and clinical presentation: 1. capsaicin-induced neurogenic inflammation through topical and intradermal administration 2. localized UVB inflammation 3. cellular model of inflammation via injection of nerve growth factor Quantification: spontaneous behaviour and nociceptive responses via physical impact stimulation with mechanical von Frey and radiant heat (CO2 laser) as well as axon reflex vasodilation (Doppler imaging). Validation: (1) Repeatability tested via stimulation of normal skin on three different parts of the body (flank, hind leg and tail); (2) All pigs receive UVB, capsaicin and placebo inflammation at three different sites within the flank; (3) Sensitivity determined via use of different dosages of inflammatory agents. So far... New application for the Von Frey anesthesiometer Optimization of set-up for an electronic IITC-von Frey anesthesiometer in the tail region. The test was performed in freely moving animals and early results suggest that mechanical stimulation can be applied without the need to stressful confinement. Effective habituation is necessary in order to exclude responses due to stimuli other than selectively nociceptive.

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