Sources of the catecholaminergic innervation of the trigeminal nucleus caudalis in cat

Injections of the retrogradely transported fluorescent dye, Evans blue, into the trigeminal nucleus caudalis were combined with the glyoxylic acid histofluorescence technique to determine the sources of catecholamine-containing varicosities innervating nucleus caudalis. Results indicate that the sources of this catecholamine innervation are widespread, originating from cell bodies throughout the brain stem including the medullary catecholamine cell groups as well as the noradrenergic nuclei of the dorsolateral pons, including locus ceruleus, subceruleus, Kölliker-Fuse, and the parabrachial nuclei. A small projection from the presumably dopaminergic neurons of the hypothalamus was also noted. The catecholamine innervation of n. caudalis in the cat is from widespread brain stem sources, a pattern different from the catecholamine innervation of the spinal cord, which receives its major catecholamine input from the Kölliker-Fuse nucleus.