Progestogen profiling in plasma during the estrous cycle in cattle using an LC-MS based approach

Area of Science:

• Reproductive Endocrinology
• Neurosteroidology
• Veterinary Science

Background:

• Progesterone (P4) is crucial for mammalian reproduction, with active metabolites influencing reproductive functions.
• Metabolites of progesterone can interact with progesterone receptors and GABA_A receptors, impacting physiological processes.

Purpose of the Study:

• To investigate the presence and profiles of reduced progesterone metabolites in bovine plasma throughout the estrous cycle.
• To compare the temporal dynamics of these metabolites with progesterone (P4) levels, especially during luteolysis.

Main Methods:

• Plasma samples from cattle during the estrous cycle were analyzed using liquid chromatography-mass spectrometry (LC-MS).
• Quantification of progesterone (P4) and its various reduced metabolites was performed.

Main Results:

• Reduced progestogens were detected in bovine plasma, exhibiting profiles that mirrored progesterone (P4) during the estrous cycle.
• Progestogen levels lagged behind the decline of P4 during luteolysis.
• The most abundant metabolites were P4, followed by allopregnanolone, pregnanolone, epipregnanolone, and 20β-DHP.

Conclusions:

• Progesterone metabolites are present in bovine plasma and their concentrations correlate with P4 levels during the estrous cycle.
• Further research is needed to fully elucidate the role of these metabolites around the critical period of luteolysis.