Vanilloid receptor 1 expression in the rat urinary tract

• Tipo: Artigo em Revista Científica Internacional
• Data: 2002

Autores

António Avelino Silva (Autor) FMUP; Cruz C.D. (Autor) Outra; Nagy, I (Autor) Outra; Francisco Cruz (Autor) FMUP

Revista

Título: Neuroscience

Vol. 109

Páginas: 787-798

ISSN: 0306-4522

Editora: Elsevier

Indexação

ISI Web of Knowledge - 185 Citações

Scopus - 213 Citações

Outras Informações

ID Authenticus: P-000-RNJ

DOI: 10.1016/s0306-4522(01)00496-1

Abstract (EN): Previous findings have shown that the capsaicin sensitivity of sensory fibres is due to the expression of a specific membrane protein, the vanilloid receptor type I (VR1). In the present work we studied the distribution, morphology and the neurochemical content of nerve fibres expressing this receptor in the rat urinary tract, Immunolabelling was pet-formed against the VR1 and the positive fibres were examined by light and electron microscopy. Colocalisation of VRI and substance P or calcitonin gene-related peptide immunoreactivities. and isolectin B4 binding, was evaluated under the confocal microscope. In addition, the effect of intravesical administration of resiniferatoxin, an ultrapotent vanilloid receptor agonist, in the receptor expression in the bladder was also studied. Numerous VR1-immunoreactive fibres were found in the mucosa and muscular layer of the entire urinary tract except the kidney. In the bladder, most fibres were also substance P- or calcitonin gene-related peptide-immuno reactive but did not bind isolectin B4. Under the electron microscope VRI immunoreactivity was confined to unmyelinated axons and varicosities containing small clear and large dense-core synaptic vesicles. They occurred beneath or among epithelial cells or closely apposed to smooth muscle cells. Intravesical resiniferatoxin decreased VR1 immunoreactivity transiently. These data indicate that primary sensory fibres expressing VR1 are extremely abundant in the rat urinary tract and that, in contrast to the skin, they belong almost exclusively to the peptide-containing sub-population of primary afferents. As capsaicin-sensitive bladder afferents are involved in nociception and reflex micturition control, the numerous free terminal nerve endings expressing VR1 in the mucosa seem more adequate to accomplish the former function. However, the close apposition between VR1-expressing fibres and smooth muscle cells suggests that they may also encode the tonus of the muscular layer.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 12