Quantitative studies of argyrophilic APUD cells in airways and intestine: effects of hypothalamic injuries

A morphometric study of argyrophilic Amine Precursor Uptake and Decarboxylase (APUD) cells in airways and intestine of guinea pigs after hypothalamic lesions is reported. APUD cell densities are expressed as APUD cell number/mm of airway or gut perimeter length and as APUD cell/100 epithelial cells. The latter ratio is useful to distinguish generalized epithelial changes from specific alterations in APUD cell densities. Lesions to anterior hypothalamic areas are known to inhibit death due to anaphylactic shock in the guinea pig by a yet to be determined mechanism. It is also known that lesions placed in other hypothalamic nuclei located in the posterior hypothalamus do not interfere with lethal anaphylaxis. Recent quantitative studies of respiratory argyrophilic APUD cells have demonstrated changes in densities of these cells during sensitization and anaphylaxis in the guinea pig, suggesting that they participate in the complex events of anaphylaxis. The present study was performed to determine whether lesions in the anterior and posterior hypothalamus result in changes in APUD cell densities that would suggest a role of the neuroendocrine system in the modulation of lethal anaphylaxis in the guinea pig. The guinea pig has 0.53±2.44 APUD cells/100 nuclei in the larynx, 0.64±0.29 in the trachea, 0.39±0.18 in bronchi, 0.03±0.03 in bronchioles and 10.40±0.70 in the ileum. No significant changes were found in APUD cell densities in animals with hypothalamic lesions when compared to controls, suggesting that mechanisms other than APUD cell hyperplasia or hypoplasia are responsible for the effects of these lesions on lethal anaphylaxis in the guinea pig.