Catecholamine projections to the spinal cord in the rat and their relationship to central cardiovascular neurons.

The organization of the neuroanatomical substrate which provides the supraspinal catecholaminergic innervation of the upper thoracic spinal cord in the rat was studied by means of retrograde labelling of neurons with primuline and other dyes, combined with simultaneous catecholamine fluorescence (FAGLU-method). It was shown that spinally projecting catecholaminergic neurons lie predominantly in the A6 and A11 groups, while a minority of these neurons are also located in the A1/C1 and A5 groups. The number of catecholamine-containing neurons in the A11 group in the rat was estimated to be 173 +/- 4. Most of them (up to 86%) were retrogradely labelled with primuline. The possible functional role of dopaminergic diencephalospinal, noradrenergic pontospinal, and adrenergic bulbospinal neuronal systems in cardiovascular control is discussed.