[Study on the hypothalamic dopaminergic activity in different stages of pregnancy and non-pregnancy].

The purpose of this study was to investigate hypothalamic dopaminergic activity in pregnant women after the administration of metoclopramide (MCP), a dopamine receptor blocker, and to investigate the effects of MCP on the placental steroid and peptide hormones, and to clarify the prolactin (PRL) releasing mechanism in the hypothalamo-pituitary axis during pregnancy using dopaminergic agents and TRH. The following results were obtained. The plasma PRL levels following intravenous MCP remained significantly elevated for 180 minutes (p less than 0.001-0.05) in all groups as compared to the control group, but there were no significant differences between early and late pregnant groups, and between pregnant and nonpregnant groups. Therefore, the dopaminergic activity of the hypothalamus remained unchanged during pregnancy as well as in the nonpregnant state. The administration of MCP or a sudden increase in plasma PRL had no effect on the maternal plasma estradiol-17 beta, progesterone, HCG or HPL during pregnancy. PRL release from the pituitary by MCP was suppressed significantly (p less than 0.01) by pretreatment with bromocriptine. PRL releasing activity of MCP 10mg was significantly higher (p less than 0.01-0.05) than that of TRH 500 micrograms in the pregnant women.