To clarify involvement of protease-activated receptor-2 (PAR-2) in parotid pain, we examined whether PAR-2 activation in the parotid gland could activate trigeminal nociceptive neurons in anesthetized rats, by analyzing immunoreactive Fos as a nociceptive marker. Either the PAR-2 agonist SLIGRL-NH2 or capsaicin, injected into the parotid duct, caused expression of Fos in the trigeminal subnucleus caudalis, although the PAR-2-inactive reversed peptide had no such effect. The Fos expression caused by PAR-2 activation was inhibited by ablation of capsaicin-sensitive sensory neurons. Intraductal SLIGRL-NH2 did not increase vascular permeability in the parotid gland. Our data thus reveal that activation of PAR-2 in the parotid gland can cause activation of trigeminal nociceptive neurons via capsaicin-sensitive sensory nerves most probably by a non-inflammatory mechanism.
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http://dx.doi.org/10.1097/01.wnr.0000134991.97051.6b | DOI Listing |
Biochem Biophys Res Commun
December 2024
Department of Dental Anesthesiology, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka, 565-0871, Japan. Electronic address:
Pain is a major non-motor symptom of Parkinson's disease (PD). The relationship between hyperalgesia and neuropeptides originating from paraventricular nucleus (PVN) in 6-hydroxydopamine (6-OHDA) rats has already been investigated for oxytocin (OXT), but not yet for arginine vasopressin (AVP) and corticotropin-releasing hormone (CRH). The present study aimed to investigate the alterations in these neuropeptides following nociceptive stimulation in PD model rats and to examine the mechanisms of hyperalgesia.
View Article and Find Full Text PDFFront Pharmacol
December 2024
Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile.
Cold allodynia is a debilitating symptom of orofacial neuropathic pain resulting from trigeminal nerve damage. The molecular and neural bases of this sensory alteration are still poorly understood. Here, using chronic constriction injury (CCI) of the infraorbital nerve (IoN) (IoN-CCI) in mice, combined with behavioral analysis, Ca imaging and patch-clamp recordings of retrogradely labeled IoN neurons in culture, immunohistochemistry, and adeno-associated viral (AAV) vector-based delivery , we explored the mechanisms underlying the altered orofacial cold sensitivity resulting from axonal damage in this trigeminal branch.
View Article and Find Full Text PDFCells
November 2024
Department of Pharmacology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan.
Post-traumatic trigeminal neuropathy (PTTN) is a sensory abnormality caused by injury to the trigeminal nerve during orofacial surgery. However, existing analgesics are ineffective against PTTN. Abnormal microglial activation in the caudal part of the spinal trigeminal nucleus caudal part (Sp5C), where the central trigeminal nerve terminals reside, plays an important role in PTTN pathogenesis.
View Article and Find Full Text PDFExp Neurol
December 2024
Department of Pharmacology, Institute of Biomedicine and Translational Medicine, University of Tartu, Ravila 19, 50411 Tartu, Estonia. Electronic address:
Wolfram syndrome (WS) is a rare condition caused by homozygous or compound heterozygous mutations in the WFS1 gene primarily. It is diagnosed on the basis of early-onset diabetes mellitus and optic nerve atrophy. Patients complain of trigeminal-like migraines and show deficits in vibration sensation, but the underlying cause is unknown.
View Article and Find Full Text PDFCurr Neuropharmacol
December 2024
Department of Biomedical Sciences, Texas A&M University School of Dentistry, Dallas, Texas, USA.
Background: Oral cancer causes intense pain at the primary site, and such pain can impair oral functions. However, the underlying mechanisms for oral cancer pain are still not fully understood. In the present study, it is investigated whether programmed cell death protein 1 (PD-1) is involved in the development of oral cancer pain.
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