The influence of mercury on the secretion of human chorionic gonadotropin in superfused young placental tissue.

Abstract

The effect of mercury (Hg), as HgCl2, in levels ranging from 0.75 to 12 micrograms/ml medium, on the secretion of human chorionic gonadotropin (hCG) was examined in first-trimester placental explants, after 6 or 24 hr incubation, employing both static and dynamic systems (the latter by superfusion). Later the unbound Hg was washed for 45 min. with fresh medium devoid of Hg, followed by superfusion with the latter medium for 75 min., during which time samples were collected for hCG assay. For the superfusion experiments the parameters used for evaluating the hCG secretion pattern were: mean peak amplitude, pulse frequency and the area under the hCG secretion curve (AUC). The results observed after 24 hr incubation indicate that in the dynamic system the hCG secretion increased significantly, and this increase was dose-dependent. There was also a dose-related increase in mean total hCG secreted by the explants exposed to Hg. Maximal hCG secretion was observed after 24 hr exposure of explants to 6 micrograms of the metal/ml. Both the mean peak amplitude and AUC parameters showed a statistically-significant increase for this dose level. At 12 micrograms/ml, the pulsatile secretion of hCG decreased, but the value for the mean hCG secretion was still higher than that observed for 0.75 and 3 micrograms/ml. After 6 hr incubation, however, there were no significant changes from the control, as judged by all of the above parameters. The levels of hCG secreted by the explants into the media in the static system were not significantly different from their respective controls, for both incubation periods and Hg levels.(ABSTRACT TRUNCATED AT 250 WORDS)