An Immunocytochemical Investigation of Human Trigeminal Nucleus Caudalis: Cgrp, Substance P and 5-Ht1D-Receptor Immunoreactivities Are Expressed by Trigeminal Sensory Fibres

• Published in: Cephalalgia Vol. 22; no. 6; pp. 424 - 431
• Main Authors: Smith, D, Hill, RG, Edvinsson, L, Longmore, J
• Format: Journal Article
• Language: English
• Published: London, England SAGE Publications 01.07.2002; Blackwell Science Ltd
• Subjects: 5-HT1D-receptors; Annan klinisk medicin; brainstem; calcitonin gene-related peptide; Calcitonin Gene-Related Peptide - metabolism; Clinical Medicine; human; human brainstem; Humans; Immunohistochemistry; Klinisk medicin; Medical and Health Sciences; Medicin och hälsovetenskap; migraine; Nerve Fibers - metabolism; Other Clinical Medicine; Receptor, Serotonin, 5-HT1D; Receptors, Serotonin - metabolism; substance P; Substance P - metabolism; Trigeminal Caudal Nucleus - anatomy & histology; Trigeminal Caudal Nucleus - metabolism; calcitonin gene-related peptide; migraine; substance P; 5-HT1D-receptors; human brainstem
• ISSN: 0333-1024; 1468-2982
• DOI: 10.1046/j.1468-2982.2002.00378.x

5-HT1D (but not 5-HT1B)-receptor immunoreactivity (i.r.) can be detected on trigeminal fibres within the spinal trigeminal tract of the human brainstem. The present study used immunohistochemical and morphometric techniques to determine the proportions of trigeminal fibres expressing substance P, CGRP or 5-HT1D-receptor immunoreactivities. Co-localization studies between 5-HT1D-receptor and substance P- or CGRP-i.r. were also performed. Brainstem material was obtained with consent (four donors) and the total number of immunoreactive fibres within the trigeminal tract was estimated using random field sampling. A greater proportion of fibres (>1 μm diameter) expressed CGRP-i.r. (80 ± 6%) compared with substance P-i.r. (46 ± 7%) or 5-HT1D-receptor-i.r. (25 ± 1%). 5-HT1D-receptor-i.r. was co-localized on some CGRP- or substance P-i.r. fibres. This suggests that 5-HT1D-receptors can regulate the release of CGRP and substance P and may be relevant to the clinical effectiveness of 5-HT1B/1D-receptor agonists in the treatment of migraine and other cranial pain syndromes.