Central brainstem projections of the superior vagal ganglion of the cat

Abstract

The central projections of the cat superior vagal (jugular) ganglion (SVG) cells were determined using anterograde transport of wheat germ agglutinin conjugated to horseradish peroxidase (WGA HRP). WGA HRP was injected into the SVG of 5 cats, 3 of which had the vagal nerve sectioned distal to the jugular ganglion several days previously. Following 72 h, the animals were sacrificed and the brainstem and rostral cervical spinal cord sectioned and processed with tetramethylbenzidine (TMB) and examined for anterograde transport. The vagal root afferent fibers entered the brainstem at the level of the caudal facial motor nucleus and bifurcated into descending tracts. Terminal label was identified in: (1) the dorsal lateral subnucleus of the nucleus tractus solitarius (NTS); (2) nucleus interpolaris and nucleus caudalis of spinal V; (3) the ventrolateral aspect of the cuneate nucleus and; (4) the superficial laminae (I, II) of the rostral C 1-dorsal horn. To our knowledge this is the first report describing central vagal afferent terminations following injection of current axonal tract tracing substances into the isolated superior vagal ganglion. The projection of jugular ganglion cells to a region of the NTS associated with cardiovascular function is of particular interest, and may be related to ganglion cells known to innervate the cerebral vasculature and meninges.