Relationship between progesterone suppression and pregnancy in rats.

Four luteolytic agents were administered to groups of pregnant rats to examine the quantitative relationship between serum progesterone levels and the maintenance of pregnancy. Each agent inhibited progesterone in a dose-dependent manner, however only three, azastene, thiosemicarbazone and dihydrotestosterone, adversely affected pregnancy. A statistical analysis of the data suggests that, regardless of the mechanism of action of a particular luteolytic agent, a treatment-induced depression of serum progesterone to concentrations less than 45% of that of the controls on day 11 of pregnancy is incompatible with pregnancy maintenance.

The biological properties of aspartame. IV. Effects on reproduction and lactation.

Intragastric administration of approximately 300 mg/kg/day of aspartame (APM) to female rats for seven days and to female hamsters for five days after mating did not affect postcoital fertility as measured by the number of implantation sites and normal appearing fetuses. In additional studies, the effect of APM fed at 1 to 14% in the diet to lactating rats and their litters of suckling young was studied using a pair-feeding experimental design. Levels of APM up to 4% in the diet (about 7 g/kg/day) did not affect food consumption, body weights, serum prolactin, serum gonadotropins, the mammary gland histology of the dams or the growth and survival rates of their pups. However, higher levels of 7.5 and 14% APM (about 9 g/kg/day) caused reduced food consumption due to diet palatability and resulted in body weight loss in dams and retarded growth rates in the young.