Bradykinin B1 receptor is constitutively expressed in the rat sensory nervous system

Using immunocytochemistry with an antibody raised to a specific rat bradyki nin B1 receptor sequence, we showed that the B1 receptor was expressed in t he naive rat sensory nervous system. B1 immunoreactivity was seen in lamina e 1 and 2 of the dorsal horn of the spinal cord, where primary afferents te rminate, and on peripheral nerve terminals in the bladder. B1 receptor was co-expressed preferentially with IB4 positive, but not calcitonin gene-rela ted peptide (CGRP) containing C-cell bodies in the dorsal root ganglion. B1 activation has an important role in the hyperalgesia associated with infla mmation, but the site of action of B1 antagonists has generally been believ ed to be on peripheral, non-neuronal cells. The striking distribution of B1 receptors on sensory neurones suggests that a direct action of B1 activato rs on the nervous system may also contribute to hyperalgesia. (C) 2000 Else vier Science Ireland Ltd. All rights reserved.