Pain
-
Motor cortex stimulation is generally suggested as a therapy for patients with chronic and refractory neuropathic pain. However, the mechanisms underlying its analgesic effects are still unknown. In a previous study, we demonstrated that cortical stimulation increases the nociceptive threshold of naive conscious rats with opioid participation. ⋯ Furthermore, motor cortex stimulation enhanced neuronal firing rate and Fos immunoreactivity in the ipsilateral periaqueductal gray. We have also observed a decreased Zif268, δ-aminobutyric acid (GABA), and glutamic acid decarboxylase expression within the same region, suggesting an inhibition of GABAergic interneurons of the midbrain periaqueductal gray, consequently activating neurons responsible for the descending pain inhibitory control system. Taken together, the present findings suggest that inhibition of thalamic sensory neurons and disinhibition of the neurons in periaqueductal gray are at least in part responsible for the motor cortex stimulation-induced antinociception.
-
Facial expressions during infancy are important to examine, as infants do not have the language skills to describe their experiences. This is particularly vital in the context of pain, where infants depend solely on their caregivers for relief. The objective of the current study was to investigate the development of negative infant facial expressions in response to immunization pain over the first year of life. ⋯ Instead, infants displayed a variety of generalized pain and distress faces aimed at gaining caregiver aid. The development of nonverbal communication in infants, particularly facial expressions, remains an important area of inquiry. Further study into accurately measuring infant negative emotions, pain, and distress is warranted.
-
The elusiveness of the mechanism underlying pain is a major impediment in developing effective clinical treatments. We examined whether the phosphorylation of spinal serum- and glucocorticoid-inducible kinase 1 (SGK1) and downstream glutamate receptor interacting protein (GRIP)-associated protein-1 (GRASP-1)/Rab4-dependent GluR1-containing α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) recycling play a role in inflammatory pain. After intraplantar injection of complete Freund's adjuvant (CFA), we assessed thermal hyperalgesia using the Hargreaves test and analyzed dorsal horn samples (L4-5) using Western blotting, coprecipitation, and immunofluorescence. ⋯ Intrathecal 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, an AMPAR antagonist, 1, 3, and 10 μM, 10 μL/rat) attenuated the hyperalgesia and GluR1 trafficking caused by CFA; however, it had no effect on SGK1 phosphorylation. Small interfering RNA targeting Rab4 hindered the CFA-induced hyperalgesia and the associated GluR1 trafficking and Rab4-GluR1 coprecipitation. Our results suggest that spinal SGK1 phosphorylation, which subsequently triggers the GRASP-1/Rab4 cascade, plays a pivotal role in CFA-induced inflammatory pain by regulating GluR1-containing AMPAR recycling in the dorsal horn.
-
Whether self-reported lifetime civilian and war-related potential traumatic events are associated with widespread pain (WP) and if so, whether the association is attributable to posttraumatic stress disorder (PTSD) and depression has not been studied in a representative sample of the general population. In a randomly selected sample of the German general population, persons aged 60-85 years answered validated self-rating instruments: Regional Pain Scale, trauma list of the Composite International Diagnostic Interview, Posttraumatic Diagnostic Scale, and Patient Health Questionnaire 2. Participants with WP were compared with participants with no or local or regional pain (controls). ⋯ The significant association between some potential traumatic events and WP was completely abrogated after adjusting for demographic variables and PTSD. In the final model, PTSD (odds ratio 3.43, 95% confidence interval 1.88-6.26) and lifetime employment status as a worker (odds ratio 1.55, 95% confidence interval 1.04-2.31) predicted WP. Prospective studies are necessary to understand the temporal association of PTSD and WP.