Spinal projections from the nucleus locus coeruleus and nucleus subcoeruleus in the cat and monkey as demonstrated by the retrograde transport of horseradish peroxidase.

The rostral pons of the cat and rhesus monkey were examined for the presence of labeled cells following injections of horseradish peroxidase (HRP) into the lumbar spinal cord. Labeled cells were found in the ipsilateral dorsolateral pontine tegmentum and in the contralateral ventrolateral pontine reticular formation. In both the cat and monkey, labeled cells were located in the nucleus locus coeruleus, nucleus subcoeruleus, in or near the Kölliker-Fuse nucleus, and in the ventral part of the lateral parabrachial nucleus. There is a striking similarity between the distribution of HRP-labeled cells in the dorsolateral pontine tegmentum of the cat and monkey and that of catecholamine-containing cells observed in this area in previous studies.