Chromatographic evidence for vasotocin biosynthesis by cultured pineal ependymal cells from rat fetuses

Cultured pineal ependymal cells from rat fetuses aged 17 to 19 days post-coitum release into their media a substance that has hydroosmotic, antidiuretic and rat uterine activities. Paper chromatography of concentrates from culture media demonstrates that the substance possessing all the above activities was eluted from a slow moving region (Rf 0.15-0.35) with a peak at 0.20-0.30. This region is not significantly different from the Rf of synthetic arginine vasotocin (AVT) used as standard. Neither hydroosmotic nor rat uterine activities could be detected in the chromatographic eluates from the fast moving region corresponding to the Rf of synthetic oxytocin (0.55-0.65) used as standard. The chromatographic mobility of biological activities from culture media, the ratio of the activities as well as their susceptibility to tryptic digestion, demonstrates the presence of a basic peptide indistinguishable from synthetic AVT. The total amount of AVT released into the medium during 43 days of incubation is about 40 times greater than the amount contained in non-incubated pineal glands of the same age, strongly suggesting de novo synthesis of AVT.