The contribution of brain stem catecholamine cell groups to the innervation of the sympathetic lateral cell column

Data are presented on the quantitative distribution of individual catecholamines, noradrenaline (NA), dopamine (DA) and adrenaline (A) determined within specific microdissected areas of the third thoracic segment of the cat spinal cord, using a radioenzymatic assay. NA was found in much higher concentrations than the other catecholamines with highest levels in medial-ventral grey matter (754 +/- 56 ng/100 mg protein) and in dorsal and intermediolateral grey matter. DA was present in much smaller amounts, but was relatively concentrated in medial and dorsal grey matter (up to 76 +/- 1 ng/100 mg protein). Very little A was detected ( less than 17 ng/100 mg protein). Experiments were carried out to determine the contribution made by various brain stem cell groups to the catecholamine innervation of the spinal cord, and in particular the sympathetic lateral column. The concentrations of the catecholamines was determined in 5 groups of animals, 3-5 days after decerebration, or decerebration together with bilateral lesions of the A1, A2, A5 or A6 groups. A major and selective NA input to the sympathetic lateral column from the A1 cell group was revealed. There may also be a small contribution from the A2 and A6 groups, but none was shown from the A5 group. The A6 group was also shown to provide a selective noradrenergic input to the ventral horn. Some evidence is presented for the origin of noradrenergic inputs to other regions, e.g. dorsal horn. The possibility of a separate dopaminergic innervation to specific regions of the spinal cord is discussed.