Segmental distribution of corticotropin-releasing factor-like and vasoactive intestinal peptide-like immunoreactivities in presumptive sympathetic preganglionic neurons of the cat.

The distribution of corticotropin-releasing factor (CRF), vasoactive intestinal peptide (VIP), and luteinizing hormone-releasing hormone (LH-RH) in cell bodies of sympathetic autonomic nuclei of the thoracolumbar spinal cord was studied immunohistochemically in cats after intrathecal administration of colchicine. Neurons containing CRF-like immunoreactivity (CRFir) and VIP-like immunoreactivity (VIPir), but not LH-RH-like immunoreactivity, were found in the intermediolateral nucleus pars principalis (IMLp) and pars funicularis (IMLf). On the basis of identification in previous studies and the size, shape, and location of the immunoreactive cells, it is suggested that the neurons are sympathetic preganglionic neurons. Most of the neurons with CRFir (85.5%) were found in the IMLp in segments T2-T7 and L2-L3 and the remaining 14.5% were found in the IMLf in segments T2-T5. The largest proportion of neurons with VIPir (93.7%) was found in the IMLp in segments T2, T4-T7, and T9-T13. Only 6.3% of the neurons containing VIPir were found in the IMLf in segments T2, T4, T5, and T10. These findings suggest that CRF and VIP may participate in peptide-specific pathways to peripheral organs.