CHROMOGRANIN-A AND PANCREASTATIN-LIKE IMMUNOREACTIVITY IN NORMAL PREGNANCIES

Placenta is a neuroendocrine organ, and we therefore wanted to study t he occurrence of the general neuroendocrine marker chromogranin A (CgA ) and its split product pancreastatin. CgA and pancreastatin-like immu noreactivity (PST-LI) were determined by ELISA and RIA methods, respec tively, in homogenates from term placentas, sera from pregnant women, nonpregnant women, umbilical cords, and in amniotic fluids. In placent al homogenates, the mean level of CgA was 7.1 +/- 8.6 pmol/g wet wt (m ean +/- SD), whereas PST-LI was not detectable. CgA immunoreactivity w as demonstrated by immunofluorescence studies of isolated trophoblasts and decidual cells from term placentas. In trophoblasts, CgA was colo calized with human chorionic gonadotropin (hCG) and human placental la ctogen. By Northern blotting, a distinct band corresponding to CgA mes senger RNA (mRNA) was demonstrated in the placental cell line, whereas , in placental homogenates, a mRNA band of a slightly larger size was found. Median CgA level in maternal sera at term tended to be higher ( median:469 pmol/L, range 61-980 pmol/L, P < 0.1) than at 6-11 weeks (2 86 pmol/L, 61-653 pmol/L) or in sera from nonpregnant women (306 pmol/ L, 204-469 pmol/L). In umbilical cord sera, median CgA level was signi ficantly higher (898 pmol/L, 102-2245 pmol/L, P < 0.05) than in term s era. Median serum level of PST-LI was significantly higher at term (38 pmol/L, 0-131 pmol/L than at 6-11 weeks (9 pmol/L (0-85 pmol/L, P < 0 .05), than in nonpregnant women (6 pmol/L, 0-52 pmol/L, P < 0.05), and in umbilical cord sera (12 pmol/L, 0-76 pmol/L, P < 0.05). In amnioti c fluid, median CgA value was significantly higher at term (1163 pmol/ L, 714-1673 pmol/L) than at 14-17 weeks (551 pmol/L, 82-980 pmol/L, P < 0.01), whereas median level of PST-LI was significantly higher at 14 -17 weeks (32 pmol/L, 6-97 pmol/L) than at term (0 pmol/L, 0-15 pmol/L , P < 0.01). To our knowledge, this is the first report describing the presence of CgA and PST-LI in placenta and amniotic fluid and the occ urrence CgA mRNA in placental tissue and in a placental cell line. The presence of CgA in placenta may indicate a physiological role in preg nancy.