DISTRIBUTION AND RELATIONSHIPS OF NEUROPEPTIDE-Y AND NADPH-DIAPHORASEIN HUMAN VENTROLATERAL MEDULLA-OBLONGATA

The ventrolateral medulla, including the Al and Cl catecholamine cell groups, corresponds to the recently defined ventrolateral intermediate reticular zone (IRt) in humans. We sought to determine whether the di stribution of neuropeptide Y (NPY) corresponds to that of subpopulatio ns of nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) reactive neurons in human ventrolateral IRt. Medullae obtained from 2 men (ages 69 and 59, no history of neurologic disease, postmortem del ay 22 and 5 h, respectively) were processed for NPY, tyrosine hydroxyl ase (TH) and NADPH-d either alone or combining NADPH-d and NPY or NADP H-d and TH, respectively. Distribution of cells was plotted using comp uter-aided reconstruction. NPY-reactive neurons were found throughout the rostrocaudal extent of the ventrolateral IRt, particularly at mid- olivary levels. The distribution of NPY immunoreactivity overlapped TH but not NADPH-d reactivity. This indicates that NPY and NADPH-d react ivity may help identify different subpopulations of neurons in human v entrolateral IRt, which may be differentially susceptible to disease.