European journal of pain : EJP
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Cold allodynia and cold hyperalgesia are both elusive features of neuropathic pain, particularly in patients with various polyneuropathies. Numerous studies have suggested that topical application of L-menthol causes temporary cold hypersensitivity and thus acts as a proxy for associated symptoms. This review summarizes studies on L-menthol-induced nociception, cold allodynia and cold hyperalgesia in vitro, in animals and in humans. ⋯ Topical high-concentration L-menthol consistently induces cold hypersensitivity in animals and humans, thus constituting a predictable surrogate model of cold allodynia and hyperalgesia. Understanding translational features of this model and its underlying mechanisms could be valuable in preclinical and human phases of drug development and in improving current treatment of patients with polyneuropathy.
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Microvascular dysfunction and ischaemia in muscle play a role in the development of cutaneous tactile allodynia in chronic post-ischaemia pain (CPIP). Hence, studies were designed to assess whether pentoxifylline (PTX), a vasodilator and haemorrheologic agent, relieves allodynia in CPIP rats by alleviating microvascular dysfunction. ⋯ Since poor tissue perfusion underlies early stages of CPIP pain, the ameliorative effect of PTX on microvascular dysfunction might account for its anti-allodynic effect in our experimental model of complex regional pain syndrome type I.
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Randomized Controlled Trial
An experimental investigation of the effect of a justice violation on pain experience and expression among individuals with high and low just world beliefs.
Perceptions of injustice are linked with poorer physical and psychological outcomes in the context of pain and injury. Violations of injustice can arise out of violations of just world belief (JWB). However, no study has yet examined whether JWB moderates the effect of justice violation on pain experience. ⋯ Our results indicate that individuals with high JWB may show particularly adverse reactions in response to justice violations in the context of acute pain experience.
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Spironolactone, a commonly used mineralocorticoid receptor antagonist, has been reported to potentiate the effect of morphine in the rat. The aim of this study was to investigate the effects of spironolactone on morphine antinociception and tissue distribution. ⋯ Spironolactone has no antinociceptive effects in thermal models of pain, but it enhances the antinociceptive effects of morphine mainly by increasing morphine central nervous system concentrations, probably by inhibiting P-gp.
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High-frequency electrical stimulation (HFS) of the human forearm evokes analgesia to blunt pressure in the ipsilateral forehead, consistent with descending ipsilateral inhibitory pain modulation. The aim of the current study was to further delineate pain modulation processes evoked by HFS by examining sensory changes in the arm and forehead; investigating the effects of HFS on nociceptive blink reflexes elicited by supraorbital electrical stimulation; and assessing effects of counter-irritation (electrically evoked pain at the HFS-conditioned site in the forearm) on nociceptive blink reflexes before and after HFS. ⋯ These findings suggest that HFS concurrently triggers hemilateral inhibitory and facilitatory influences on nociceptive processing over and above more general effects of counter-irritation. The inhibitory influence may help limit the spread of sensitization in central nociceptive pathways.