Stimulatory effect of PGF2α on PRL based on experimental inhibition of each hormone in mares.

This study investigates the correlation between the hormones PGF2α and PRL in mares, and whether the synchrony of their peak pulses signifies PGF2α influencing PRL or vice versa. Results confirmed that PGF2α influences PRL output.

Study Objective and Methodology

• The primary objective of the study was to understand the synchronization of PGF2α and PRL hormone peaks in mares, particularly if one hormone influences the production of the other.
• To achieve this, the researchers conducted experiments on a set of control mares and two groups treated with different hormone inhibitors, flunixin meglumine (FM-to inhibit PGF2α) and bromocriptine (to inhibit PRL).
• The study was done at 14 days postovulation in June and September on 6 mares/group/month.
• Blood samples were collected hourly from Hour 0 to Hour 10 for analysis.

Findings and Observations

• PGFM (PGF2α metabolite) concentrations in the FM group were found to be lower at Hours 4 to 6 than in the controls in both months, meaning the FM inhibitor effectively suppressed PGF2α production.
• The bromocriptine used to inhibit PRL showed no detected impact on PGFM, indicating PRL does not influence PGF2α.
• Across all groups, the PGFM concentrations did not significantly change between June and September.
• PRL levels in June were lower in both the FM group and the bromocriptine group compared to the control group, particularly noticeable from Hours 4 to 10.
• Total PRL concentration, averaged over all groups, was considerably higher in June than in September.

Conclusions

• From these results, the researchers concluded that the association between PGFM and PRL concentrations in mares signifies the effect of PGF2α on PRL rather than the other way around.
• This finding could be influential in understanding the hormonal dynamics in mares, particularly regarding fluctuations in PGF2α and PRL hormones.