CALCITONIN, CGRP AND HELODERMIN IN ENDOCRINE-CELLS OF THE DEVELOPING RAT LUNG

Calcitonin gene-related peptide (CGRP), calcitonin and immunoreactive helodermin occur in endocrine cells in the murine airways. In the lung s these cells form clusters, while they occur scattered in the larynx and trachea. In the present study of the developing rat CGRP-immunorea ctive cells were more numerous at all stages than the calcitonin- and helodermin-containing ones. A subpopulation of the CGRP-containing cel ls contained either calcitonin or helodermin. Immunocytochemistry reve aled a higher density of CGRP-containing endocrine cells in the lungs of fetal and newborn rats than in the lungs of older rats, while the d ensity of calcitonin containing cells was largely unchanged. The helod ermin-containing cells were few al all developmental stages examined. The concentration and content of CGRP were highest in newborn rats; th e levels decreased postnatally. The calcitonin concentration did not c hange during development while the content increased with age. The con centration and content of helodermin increased with age.