Distribution of 5-HT1 binding sites in cat spinal cord

Quantitative analysis of high affinity [3H]5-HT binding to 5-HT1 receptors in the cervical, thoracic, lumbar, and sacral spinal cord of the cat revealed specific binding throughout the grey matter, with the highest levels of binding in laminae II and III, and the lowest levels in laminae I and VII. Relatively high levels were also observed in the thoracic intermediolateral cell column. There were no significant differences in the degree of binding between various segmental levels. Comparison of these data with published maps of 5-HT immunoreactivity reveals--with the exception of lamina I--a close correspondence between the degree of immunoreactivity and the degree of 5-HT binding. These results suggest that 5-HT plays an important role in a variety of spinal cord sensory, motor and autonomic functions.