Distribution and relationships of neuropeptide Y and NADPH-diaphorase in human ventrolateral medulla oblongata

Abstract

The ventrolateral medulla, including the A1 and C1 catecholamine cell groups, corresponds to the recently defined ventrolateral intermediate reticular zone (IRt) in humans. We sought to determine whether the distribution of neuropeptide Y (NPY) corresponds to that of subpopulations 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 delay 22 and 5 h, respectively) were processed for NPY, tyrosine hydroxylase (TH) and NADPH-d either alone or combining NADPH-d and NPY or NADPH-d and TH, respectively. Distribution of cells was plotted using computer-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 reactivity may help identify different subpopulations of neurons in human ventrolateral IRt, which may be differentially susceptible to disease.