The CNS cell groups that innervate the sympathoadrenal preganglionic neurons of rats
were identified by a transneuronal viral cell body labeling technique combined with
neurotransmitter immunohistochemistry. Pseudorabies virus was injected into the adrenal
gland. This resulted in retrograde viral infections of the ipsilateral sympathetic
preganglionic neurons (T4-T13) and caused retrograde transneuronal cell body infections
in 5 areas of the brain: the caudal raphe nuclei, ventromedial medulla, rostral ventrolateral
medulla, A5 cell group, and paraventricular hypothalamic nucleus (PVH). In the spinal
cord, the segmental distribution of virally infected neurons was the same as the retrograde
cell body labeling observed following Fluoro-gold injections in the adrenal gland
except there was almost a 300% increase in the number of cells labeled and a shift
in cell group distribution. These results imply there are local interneurons that
regulate the sympathoadrenal preganglionic neurons. In the medulla oblongata, serotonin
(5-HT)-, substance P (SP)-, thyrotropin-releasing hormone-, Met-enkephalin-, and somatostatin-immunoreactive
neurons of the raphe pallidus and raphe obscurus nuclei and the ventromedial medulla
were infected. In the ventromedial and rostral ventrolateral medulla, immunoreactive
phenylethanolamine-N-methyltransferase, SP, neuropeptide Y, somatostatin, and enkephalin
neurons were infected. The A5 noradrenergic cells were labeled, as were some somatostatin-immunoreactive
neurons in this area. In the were infected. The A5 noradrenergic cells were labeled,
as were some somatostatin-immunoreactive neurons in this area. In the hypothalamus,
tyrosine hydroxylase- and SP-immunoreactive neurons of the dorsal parvocellular PVH
were infected. Only a few immunoreactive vasopressin, oxytocin, Met-enkephalin, neurotensin,
and somatostatin PVH neurons were labeled.