Regional distribution of a novel pituitary protein (7B2) in the rat spinal cord: effect of neonatal capsaicin treatment and thoracic cord transection.

Using a specific radioimmunoassay, a novel pituitary protein (7B2) was shown to be distributed throughout the rat spinal cord. The concentration of 7B2-like immunoreactivity (7B2-IR) was significantly higher in dorsal lumbar than in whole lumbar cord, and the highest level was found in the sacral region. On both gel and high-performance liquid chromatography, 7B2-IR in rat spinal cord eluted in the same position as 7B2-IR extracted from porcine pituitary gland. Neonatal capsaicin treatment did not change dorsal lumbar spinal cord 7B2-IR concentrations, suggesting that it is not predominantly present in unmyelinated primary afferent fibres. Thoracic cord transection, however, resulted in significant increases of 7B2-IR in lumbar and especially sacral regions, providing evidence of a 7B2-containing ascending pathway originating in the lumbosacral spinal cord.