Adrenergic projection from the caudal part of the nucleus of the tractus solitarius to the parabrachial nucleus in the rat: immunocytochemical study combined with a retrograde tracing method.

The presence of an adrenergic projection from the nucleus of the tractus solitarius (NTS) to the parabrachial nucleus (PB) was demonstrated by the immunocytochemistry combined with a retrograde tracing method. Numerous neurons containing both phenylethanolamine N-methyltransferase, a marker for adrenaline, and wheat germ agglutinin-conjugated horseradish peroxidase, a retrograde tracer, were detected in the dorsolateral part of the NTS at the level of the area postrema after injection of the tracer into the dorsal PB.