Basal expression of bradykinin B₁ receptor in the spinal cord in humans and rats

The bradykinin B₁ receptor has been considered as a receptor induced by tissue injury and inflammation mainly in the peripheral tissues. In the present study, we have investigated whether there is a basal expression in the spinal cord by both reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemical staining methods. Southern blotting of the DNA reverse-transcribed from human and rat spinal cord mRNA and amplified by polymerase chain reaction (PCR) showed a substantial basal B₁ receptor expression in both human and rat spinal cord. Immunohistochemical staining demonstrated B₁-positive neurons in the spinal cord dorsal horn, suggesting that the B₁ receptor is constitutively expressed by spinal neurons.