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Relationship between progesterone suppression and pregnancy in rats
The Journal of Pharmacy and Pharmacology
|May 1, 1987
Summary
Maintaining pregnancy in rats requires serum progesterone levels above 45% of control values by day 11. Lowering progesterone with luteolytic agents like azastene, thiosemicarbazone, or dihydrotestosterone can disrupt pregnancy.
Area of Science:
- Reproductive biology
- Endocrinology
- Pharmacology
Background:
- Progesterone is crucial for maintaining pregnancy.
- Luteolytic agents can reduce progesterone levels.
- The precise progesterone threshold for pregnancy maintenance is not fully understood.
Purpose of the Study:
- To investigate the quantitative relationship between serum progesterone levels and pregnancy maintenance in rats.
- To determine the critical progesterone concentration below which pregnancy cannot be sustained.
Main Methods:
- Pregnant rats were administered four different luteolytic agents.
- Serum progesterone levels were measured.
- The impact of progesterone reduction on pregnancy outcomes was assessed.
- Statistical analysis was performed to identify a threshold.
Main Results:
- All four agents inhibited progesterone in a dose-dependent manner.
- Three agents (azastene, thiosemicarbazone, dihydrotestosterone) adversely affected pregnancy.
- A serum progesterone level below 45% of controls on day 11 was associated with pregnancy failure.
Conclusions:
- Progesterone levels below 45% of controls on day 11 are incompatible with pregnancy maintenance in rats.
- The mechanism of the luteolytic agent does not alter this critical progesterone threshold.
- This finding provides a quantitative marker for assessing the risk of pregnancy loss due to luteolysis.