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Background: Dental treatment associated with unadaptable occlusal alteration can cause chronic primary myofascial orofacial pain. The serotonin (5-HT) pathway from the rostral ventromedial medulla (RVM) exerts descending modulation on nociceptive transmission in the spinal trigeminal nucleus (Sp5) and facilitates chronic pain. The aim of this study was to investigate whether descending 5-HT modulation from the RVM to the Sp5 is involved in the maintenance of primary myofascial orofacial hyperalgesia after persistent experimental occlusal interference (PEOI) or after delayed removal of experimental occlusal interference (REOI).
Methods: Expressions of 5-HT3A and 5-HT3B receptor subtypes in the Sp5 were assessed by immunofluorescence staining and Western blotting. The release and metabolism of 5-HT in the Sp5 were measured by high-performance liquid chromatography. Changes in the pain behavior of these rats were examined after specific pharmacologic antagonism of the 5-HT3 receptor, chemogenetic manipulation of the RVM 5-HT neurons, or selective down-regulation of 5-HT synthesis in the RVM.
Results: Upregulation of the 5-HT3B receptor subtype in the Sp5 was found in REOI and PEOI rats. The concentration of 5-HT in Sp5 increased significantly only in REOI rats. Intrathecal administration of Y-25130 (a selective 5-HT3 receptor antagonist) dose-dependently reversed the hyperalgesia in REOI rats but only transiently reversed the hyperalgesia in PEOI rats. Chemogenetic inhibition of the RVM 5-HT neurons reversed the hyperalgesia in REOI rats; selective down-regulation of 5-HT in advance also prevented the development of hyperalgesia in REOI rats; the above two manipulations did not affect the hyperalgesia in PEOI rats. However, chemogenetic activation of the RVM 5-HT neurons exacerbated the hyperalgesia both in REOI and PEOI rats.
Conclusions: These results provide several lines of evidence that the descending pathway from 5-HT neurons in the RVM to 5-HT3 receptors in the Sp5, plays an important role in facilitating the maintained orofacial hyperalgesia after delayed EOI removal, but has a limited role in that after persistent EOI.
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http://dx.doi.org/10.1186/s10194-023-01584-3 | DOI Listing |
Neuropsychopharmacology
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Neuroscience Center, HiLIFE, University of Helsinki, Helsinki, Finland.
Chronic treatment with fluoxetine, a widely prescribed selective serotonin reuptake inhibitor (SSRI), is known to promote neural plasticity. The role of fluoxetine in plasticity has been particularly tied to parvalbumin-positive interneurons, a key population of GABAergic neurons that regulate inhibitory tone and network stability. While our previous studies have highlighted fluoxetine-induced plasticity in the visual cortex and hippocampus, its cell-type-specific effects in the prefrontal cortex (PFC) remain unclear.
View Article and Find Full Text PDFFront Neurol
August 2025
Nuffield Department of Clinical Neurosciences, Oxford University Centre For Integrative Neuroimaging, Oxford, United Kingdom.
Introduction: Amblyopia is a neurodevelopmental visual disorder treated with occlusion or pharmacological penalization of the dominant, non-amblyopic eye in early childhood. After early childhood, efficacy of occlusion therapy is limited due to a reduction in neuronal plasticity, and no mainstay clinical treatment is available. Selective serotonin reuptake inhibitors (SSRIs) have been hypothesized to enhance neuroplasticity in the adult brain, thereby facilitating improvements in amblyopia.
View Article and Find Full Text PDFFront Public Health
September 2025
Department of Neurology, Affiliated Hospital 6 of Nantong University, Yancheng Third People's Hospital, Yancheng, China.
Objective: To investigate the neural and molecular correlates of occupational burnout in nurses by integrating resting-state fMRI (rs-fMRI), clinical assessments, brain-wide gene expression, and neurotransmitter atlases.
Methods: Fifty-one female nurses meeting burnout criteria and 51 matched healthy controls underwent 3 T rs-fMRI. We analyzed fractional amplitude of low-frequency fluctuations (fALFF) and seed-based functional connectivity (FC), correlating findings with burnout (emotional exhaustion [EE], depersonalization [DP], and personal accomplishment [PA]).
J Hand Surg Glob Online
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Department of Plastic Surgery, Vanderbilt University Medical Center, Nashville, TN.
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View Article and Find Full Text PDFJ Cereb Blood Flow Metab
September 2025
Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria.
Functional PET (fPET) identifies stimulation-specific changes of physiological processes, individual molecular connectivity and group-level molecular covariance. Since there is currently no consistent analysis approach available for these techniques, we present a toolbox for unified fPET assessment. The toolbox supports analysis of data obtained with a variety of radiotracers, scanners, experimental protocols, cognitive tasks and species.
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