CORTICOTROPIN-RELEASING FACTOR-LIKE IMMUNOREACTIVITY IN AFFERENT-PROJECTIONS TO THE SACRAL SPINAL-CORD OF THE CAT

Distribution and origin of corticotropin releasing factor (CRF) in the thoraco-lumbar and sacral spinal cord of the cat has been studied usi ng immunohistochemical method. CRF immunoreactive (CRF-IR) nerve fiber s and terminals were most prominent in dorsal part of sacral spinal co rd, In the sacral segments of the spinal cord, immunoreactivity for CR F was detected in a prominent bundle of axons and varicosities extendi ng from Lissauer's tract (LT) along the lateral edge of the superficia l dorsal horn (laminae I and II) to laminae V at the base of the dorsa l horn. Individual CRF-IR fibers passed from the bundle in ventral med ial and ventrolateral directions to the dorsal commissure and the sacr al preganglionic nucleus (SPN), respectively, The bundle of CRF-IR axo ns closely resembled vasoactive intestinal polypeptide (VIP) containin g fibers in LT and on the lateral edge of the dorsal horn, Sacral dors al root transection eliminated both the CRF and VIP fiber staining in the dorsal horn. Spinal transection at the T12-T13 segmental level did not influence the CRF- or VIP-IR. Less intense CRF-IR was also presen t in fibers in: (1) the dorsal lateral funiculus adjacent to LT, (2) t he superficial layers of the dorsal horn and intermediolateral nucleus at thoracolumbar spinal levels, (3) the ventral horn, including Onuf' s nucleus, (4) the intermediate gray matter including the dorsal gray commissure, and (5) the SPN, The similarity in the distribution of CRF -IR and pelvic nerve afferent projections in the sacral spinal cord ra ises the possibility that CRF may be a transmitter in afferent neurons innervating the pelvic viscera.