Sympathetic preganglionic neurons projecting to the adrenal medulla and aorticorenal ganglion in the rabbit.

The distribution of sympathetic preganglionic neurons (SPN) projecting to the adrenal medulla and the aorticorenal ganglion in the rabbit was studied using a dual retrograde transport technique. The B subunit of cholera toxin (CTB) was injected into the left adrenal medulla and wheatgerm agglutinin-apo-horseradish peroxidase-7 nm gold (WGA-apo-HRP-gold) was injected into the left aorticorenal ganglion. Retrogradely transported CTB was detected by immunohistochemistry, while gold particles were detected by silver intensification. SPN projecting to the adrenal medulla were observed in segments T2-L2 of the spinal cord in 5 rabbits, with the majority of cells within segments T6-T11 (79%). SPN projecting to the aorticorenal ganglion were seen in segments T2-L1 of the spinal cord in 5 rabbits, with the greatest number of the cells within T6-T11 (81%). Only a small number of doubly labelled cells (1%) were found in two rabbits. The results suggest that despite their similar segmental distribution SPN projecting to the adrenal medulla or the aorticorenal ganglion belong to separate populations and few, if any, individual SPN have axonal projections to both locations.