ONTOGENIC EXPRESSION OF CHROMOGRANIN-A AND ITS DERIVED PEPTIDES, WE-14 AND PANCREASTATIN, IN THE RAT NEUROENDOCRINE SYSTEM

The ontogenetic expression of chromogranin A (CgA) and its derived pep tides, WE-14 and pancreastatin (PST), was studied in the rat neuroendo crine system employing immunohistochemical analysis of fetal and neona tal specimens from 12.5-day embryos (E12.5), to 42-day postnatal (P42) rats. C(g)A immunostaining was first detected in endocrine cells of t he pancreas, stomach, intestine, adrenal gland and thyroid at E13.5, E 14.5, E15.5, E15.5 and E18.5, respectively. PST-like immunoreactivity was detected in endocrine cells of the pancreas at E13.5, stomach, int estine at E15.5, adrenal gland at E17.5 and thyroid at E18.5. WE-14 im munoreactivity was first observed in the immature pancreas at E15.5, m ucosal cells of the stomach at E15.5, scattered chromaffin cells in th e immature adrenal gland and mucosal cells of the intestine at E17.5 a nd thyroid parafollicular cells at E18.5. These data confirm that the translation of the CgA gene is regulated differentially in various neu roendocrine tissues and, moreover, suggests that the posttranslational processing of the molecule is developmentally controlled.