Pulmonary gastrin-releasing peptide expression in anencephaly

Gastrin-releasing peptide (GRP) is a developmentally regulated bioactive peptide believed to function as a pulmonary growth factor. It is produced by pulmonary neuroendocrine cells, found within the conducting and respiratory epithelium, as isolated cells and in clusters known as neuroepithelial bodies (NEBs). Deficient GRP expression has been reported in pulmonary hypoplasia (PH) associated with oligohydramnios and diaphragmatic hernia. To assess further the role of GRP in maldeveloped lung we reviewed the postmortem records and histologic lung sections, stained with H&E and anti-GRP antiserum, from 11 infants with anencephaly and 11 age-matched controls. Cells immunoreactive for GRP were quantified (isolated versus NEBs) in airways and airspaces per mm2 for a standard area. PH was present in five anencephalic infants. There was no difference in the total number of GRP-positive cells, number of NEBs, size of NEBs, or number of GRP-positive cells in airways or alveoli in either group regardless of lung development. A greater proportion of the GRP-positive cells was present in the airways in anencephalic infants with PH (58%) compared with anencephalic infants without PH (40%) (P = .018). There were no differences when comparing these groups with control infants and no differences in the density of airways in each of these groups. We conclude that deficient GRP expression is not a feature of lung hypoplasia in anencephalic infants. The altered distribution of GRP-positive cells in anencephalic infants with PH may be a reflection of the structural abnormalities or accompanying altered cellular maturity.