Vasoactive intestinal polypeptide (VIP)-containing neurons in the spinal cord of the rat and their projections

The distribution of vasoactive intestinal polypeptide (VIP)-like immunoreactive structures in the rat spinal cord and their projections were investigated by means of an immunofluorescent method. In the normal rat, a small number of VIP-positive fibers were observed in the superficial layer of the dorsal horn and in the lateral funiculus. With colchicine pretreatment, VIP-positive neurons were demonstrated in the lateral spinal nucleus (lsn) and in the lamina X (Rexed). Transections of the spinal cord at various levels revealed that some of the VIP neurons in the lsn might project to supraspinal areas via lateral funiculus.