The bradykinin B1 receptor has been considered as an important mediator for inflammatory pain. In the present study, we have investigated the fibre types of sciatic nerve primary sensory neurones that express B1 receptors by retrograde tracing in combination with immunohistochemical staining, or double-immunohistochemical staining. Approximately 12% of the A-fibre dorsal root ganglion neurones, retrogradely labelled from an intra-sciatic nerve injection of fluorescein isothiocyanate-conjugated cholera toxin B subunit, were B1 receptor-immunoreactive. Over 70% of the small diameter dorsal root ganglion neurones, retrogradely labelled from an intra-sciatic nerve injection of tetramethylrhodamine isothiocyanate-conjugated wheat germ agglutinin, were B1 receptor-immunoreactive. Over 50% of the (predominantly non-peptidergic) C-fibre dorsal root ganglion neurones, retrogradely labelled from an intra-sciatic nerve injection of fluorescein isothiocyanate-conjugated Bandeiraea simplicifolia isolectin B4, were B1 receptor-immunoreactive. When calcitonin gene-related peptide, which is contained mainly in small caliber C- and Aδ-fibre primary afferents, and B1 receptors were stained with a double-immunofluorescent method, over 80% of the calcitonin gene-related peptide-positive dorsal root ganglion neurones were B1 receptor-immunoreactive. From these results we suggest that B1 receptors are predominantly expressed by small diameter primary afferent neurones that give rise to sciatic nerve fibres, which include both peptidergic and non-peptidergic C-fibres and Aδ-fibres. Since peripheral nociceptive information is primarily transmitted by C- and Aδ-fibres, B1 receptors may be involved in the modulation of nociceptive transduction or transmission.
- Bandeiraea simplicifolia isolectin B4
- Calcitonin gene-related peptide
- Cholera toxin B subunit
- Dorsal root ganglia
- Wheat germ agglutinin
ASJC Scopus subject areas
- General Neuroscience