The journal of pain : official journal of the American Pain Society
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Chronic vulvar pain is alarmingly common in women of reproductive age and is often accompanied by psychological distress, sexual dysfunction, and a significant reduction in quality of life. Localized provoked vulvodynia (LPV) is associated with intense vulvar pain concentrated in the vulvar vestibule (area surrounding vaginal opening). To date, the origins of vulvodynia are poorly understood, and treatment for LPV manages pain symptoms, but does not resolve the root causes of disease. ⋯ Inhibiting expression of one or both bradykinin receptors significantly reduces proinflammatory mediator production. Finally, we determined that bradykinin activates nuclear factor (NF)κB signaling (a major inflammatory pathway), whereas inhibition of NFκB successfully ablates this response. These data suggest that therapeutic agents targeting bradykinin sensing and/or NFκB may represent new, more specific options for LPV therapy.
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Randomized Controlled Trial
Involvement of opioid receptors and α2-adrenoceptors in inhibitory pain modulation processes: a double-blind placebo-controlled crossover study.
In healthy humans, high-frequency electrical stimulation (HFS) of the forearm not only evokes local signs of central sensitization but also triggers broader ipsilateral inhibitory influences on pain akin to a lateralized form of conditioned pain modulation. Paradoxically, some of these inhibitory influences are augmented by α2-adrenoceptor blockade. To determine whether opioid peptides mediate inhibitory effects after HFS, the opioid receptor antagonist naltrexone was coadministered orally with the α2-adrenoceptor antagonist yohimbine in 16 healthy women in a double-blind placebo-controlled crossover study. ⋯ Unlike yohimbine alone, the naltrexone with yohimbine combination blocked analgesia evoked by HFS in the ipsilateral forehead to blunt pressure, and opposed the ipsilateral inhibitory effect of pain in the temple on electrically-evoked pain at the HFS-treated site in the forearm. These findings imply involvement of opioid peptides in an ipsilateral analgesic response that complements the more generalized form of conditioned pain modulation. Opioid mediation of this ipsilateral analgesic response appears to override opposing α2-adrenoceptor effects.
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Opioid misuse, abuse, and overdose are a rapidly growing public health epidemic. Medicaid Lock-In Programs (MLIPs) are designed to prevent overutilization of controlled substances by Medicaid patients. However, despite widespread use, there is little information on their effect. ⋯ In our sample of 6,148 MLIP patients, the odds of having any opioid claim in a given month was 84% lower during MLIP enrollment relative to the period before enrollment (odds ratio = .16). MLIP enrollment also corresponded with a reduction in monthly number of opioid prescriptions by 1.13, monthly number of pharmacies by .61, and monthly Medicaid expenditures by $22.78. Although MLIPs may constitute a successful component of comprehensive efforts to reduce the potential overutilization of opioids, care should be taken to ensure that programs such as MLIPs do not constrain patients' legitimate needs for analgesic medications.
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Catastrophizing is a potent psychological modulator of pain across several chronic pain populations; yet despite evidence that patients with sickle cell disease (SCD) catastrophize more than patients with other chronic pain conditions, previous research indicates that catastrophizing is not related to sickle cell pain after controlling for relevant covariates such as depression. Recent research suggests that pain-related catastrophizing should be assessed across pain contexts (eg, dispositional and situational). In this study, we measured disease-specific, general non-disease-related, and situational catastrophizing and assessed the relationship between these contextual dimensions of catastrophizing and laboratory and clinical pain among patients with SCD. ⋯ SCD-specific and non-SCD catastrophizing were associated with clinical pain outcomes, and situational catastrophizing with markers of central sensitization and laboratory pain. Further examination of the time course of laboratory responses revealed that increases in situational catastrophizing were associated with subsequent increases in laboratory pain sensitivity. Taken together, results show the relevance of catastrophizing in understanding pain in SCD, and suggest that context-specific anchors may be beneficial in predicting different aspects of the pain experience (eg, chronic pain, pain sensitization).
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Stimulation-evoked antinociception (SEA) from the anterior pretectal nucleus (APtN) activates mechanisms that descend to the spinal cord through the dorsolateral funiculus, but the encephalic route followed by the descending pathways from the APtN is not completely known. This study evaluated the changes in the SEA from the APtN in the Wistar rat tail-flick test after lidocaine-induced neural block or N-methyl-d-aspartate-induced neurotoxic lesion of the deep mesencephalic nucleus (DpMe), tegmental pedunculopontine nucleus (PPTg), or lateral paragigantocellular nucleus (LPGi). ⋯ Antinociception did not occur when APtN stimulation was carried out 5 minutes after lidocaine or 6 days after N-methyl-d-aspartate injections into the contralateral DpMe and the ipsilateral LPGi, or into the contralateral PPTg and the ipsilateral LPGi. We conclude that the SEA from the APtN activates 2 descending pain inhibitory pathways, one relaying in the ipsilateral LPGi and another relaying sequentially in the contralateral DpMe and PPTg.