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A possible role for testosterone during luteolysis in the ewe.
1Department of Veterinary Physiology and Pharmacology, University of Liverpool.
Research in Veterinary Science
|September 1, 1988
Summary
Testosterone increases signal luteolysis and oestrus in sheep. Suppressing testosterone with spironolactone delays these events, suggesting testosterone
Area of Science:
- Reproductive endocrinology
- Animal physiology
Background:
- Peripheral plasma testosterone concentrations increase at luteolysis and oestrus in sheep.
- Testosterone's role in regulating reproductive cyclicity requires further elucidation.
Purpose of the Study:
- To investigate the role of testosterone in luteolysis and oestrus in sheep.
- To determine the effect of spironolactone, a testosterone synthesis inhibitor, on the ovine oestrous cycle.
Main Methods:
- Daily subcutaneous administration of spironolactone (10 mg kg-1) to ewes between days 10 and 16 of the oestrous cycle.
- Monitoring peripheral plasma concentrations of testosterone and progesterone.
- Assessing the timing of luteolysis and oestrus.
Main Results:
- Spironolactone administration suppressed testosterone secretion.
- Spironolactone treatment delayed luteolysis and oestrus.
- In pregnant ewes, testosterone levels did not increase between days 10-16 post-mating, and luteal regression was inhibited.
Conclusions:
- Testosterone plays a crucial role in initiating luteolysis and oestrus in sheep.
- Inhibition of testosterone synthesis disrupts normal reproductive cyclicity.
- Aromatisation of testosterone to oestrogens is proposed as a necessary step for luteolysis in sheep.