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Patients with systemic lupus erythematosus (SLE) often suffer from chronic pain. Little is known about the peripheral mechanisms underlying the genesis of chronic pain induced by SLE. The aim of this study was to investigate whether and how membrane properties in nociceptive neurons in the dorsal root ganglions (DRGs) are altered by SLE. We found elevation of resting membrane potentials, smaller capacitances, lower action potential thresholds and rheobases in nociceptive neurons in the DRGs from MRL/lpr mice (an SLE mouse model) with thermal hyperalgesia. DRGs from MRL/lpr mice had increased protein expressions in TNFα, IL-1β, and phosphorylated ERK but suppressed AMPK activity, and no changes in sodium channel 1.7 protein expression. We showed that intraplantar injection of Compound C (an AMPK inhibitor) induced thermal hyperalgesia in normal mice while intraplantar injection of AICAR (an AMPK activator) reduced thermal hyperalgesia in MRL/Lpr mice. Upon inhibition of AMPK membrane properties in nociceptive neurons from normal control mice could be rapidly switched to those found in SLE mice with thermal hyperalgesia. Our study indicates that increased excitability in peripheral nociceptive sensory neurons contributes to the genesis of thermal hyperalgesia in mice with SLE, and AMPK regulates membrane properties in nociceptive sensory neurons as well as thermal hyperalgesia in mice with SLE. Our study provides a basis for targeting signaling pathways regulating membrane properties of peripheral nociceptive neurons as a means for conquering chronic pain caused by SLE. [ABSTRACT FROM AUTHOR]

BackgroundThe aim of this study was to test the ability of the Chinese version of the Mood Disorder Questionnaire (MDQ) to identify Bipolar Disorders (BD) in patients diagnosed with Major Depressive Disorder (MDD) or Unipolar Disorder (UD) in the clinical setting.Methods1,487 being treated for MDD or UD at 12 mental health centers across China, completed the MDQ and subsequently examined by the Mini International Neuropsychiatric Interview (MINI). Receiver Operating Characteristic(ROC) curves were used to determine the ability of the MDQ to differentiate between BD (BD, BD-I and BD-II) and MDD or UD and patients with BD-I from patients with BD-II.ResultsOf the 1,487 patients, 309 (20.8%) satisfied the DSM-IV criteria for BD: 118 (7.9%) for BD-I and 191 (12.8%) for BD-II. When only part one of the MDQ was used, the best cutoff was 7 between BD and UD (sensitivity 0.66, specificity 0.88, positive predictive value 0.59, negative predictive value 0.91), 6 between BD-II and UD, and 10 between BD-I and BD-II. If all three parts of the MDQ were used, the MDQ could not distinguish between BD and UD at a cutoff of 7 (or 6), and the sensitivity was only 0.22 (or 0.24).ConclusionThe Chinese version of the MDQ had good psychometric features in screening bipolar disorders from depressive patients with mood disorders when part two and part three of the MDQ were ignored.