4-Nitroquinoline 1-oxide-induced pulmonary endocrine cell hyperplasia in Syrian golden hamster

The tumorigenic effects of 4-nitroquinoline 1-oxide (4NQO) on the hamster lung were examined by light and electron microscopy. The hamsters received three subcutaneous injections of 4NQO at a dose of 20 mg/kg body weight at weekly intervals, and were sacrificed at 20, 25, and 30 weeks after the first injection. Hyperplastic endocrine cell lesions were consistently demonstrated in the airway from the lobar bronchi to the bronchiolo-alveolar junctional area by serial sectioning of lung tissue slices of all the treated animals. The hyperplastic lesions contained argyrophilic cells and showed weakly positive immunoreactivity to neuron-specific enolase. Ultrastructurally, some of the cells contained small cored dense granules.