European journal of pain : EJP
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Peripheral opioid receptor expression is up-regulated under inflammatory conditions, which leads to the increased efficacy of peripherally administered opioids. Sex differences in the effects of inflammation, cytokines and gonadal hormones on μ-opioid receptor (MOR) expression in trigeminal ganglia (TG) are not well understood. ⋯ Collectively, these data indicate that testosterone plays a key role in the regulation of MOR in TG under inflammatory conditions, and that sex differences in the anti-hyperalgesic effects of peripherally administered opioids are, in part, mediated by peripheral opioid receptor expression levels.
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Inflammatory responses and morphological changes of radiofrequency-induced rat sciatic nerve fibres.
Recently, the pulsed radiofrequency (PRF, pulsed fashion) procedure was introduced for neuropathic pain management. Since PRF-induced lesions do not need high temperature compared with conventional continuous RF (CRF)-induced lesions, there is no significant loss of sensory fibres after application. ⋯ PRF-induced pain relief may be due to temporary blockage of nerve signals through the nerve pathway responsible for reversible neuronal depression. However, CRF-induced pain relief may be due to permanent blockage of nerve signals through other nerve pathways. Therefore, CRF could be applied to chronic inflammatory models used to study the mechanism of neuropathic pain.
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Randomized Controlled Trial
Tropisetron alleviate early post-operative pain after gynecological laparoscopy in sevoflurane based general anaesthesia: A randomized, parallel-group, factorial study.
Studies have suggested that 5-hydroxytryptamine-3A (5-HT-3A) receptor antagonists may have analgesic effects. This randomized, double-blind, placebo-controlled, factorial study tested the hypothesis that 5-HT-3A receptor antagonist tropisetron attenuates post-operative pain in women receiving either sevoflurane or propofol based anaesthesia. ⋯ A single-dose intravenous administration of tropisetron after anaesthesia induction is associated with statistically significant decreased early post-operative pain in patients undergoing gynaecological laparoscopies under sevoflurane based general anaesthesia.
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Innate responses against spontaneous pain are proposed to improve the predictive validity of preclinical analgesia models. Therefore, development and validation of novel readouts is necessary. To investigate whether innate rodent burrowing is a useful alternative behavioural readout for assessment of analgesic efficacy, a complete Freund's adjuvant (CFA)-induced model of sub-chronic inflammation was used to compare the effects of naproxen, ibuprofen and pregabalin in weight-bearing (WB), open-field (OF) and burrowing assays. ⋯ Burrowing performance is an alternative non-reflex readout relying on innate rodent behaviour that is affected by nociceptive behaviour and can be pharmacologically manipulated. The burrowing assay appears to be more sensitive than OF assays and is as sensitive as WB assays at distinguishing between analgesic doses and doses that impair locomotion.