Temporal relationships of a pulse of prolactin (PRL) to a pulse of a metabolite of PGF2α in mares.

The research investigates the rhythmicity and coordination of pulses of prolactin and a metabolite of prostaglandin F2α in mares, establishing the first report on characterization of these pulses and their higher activity during the luteolytic and postluteolytic periods.

Methodology

• The research was conducted with 10 mares from which hourly blood samples were collected over a 24-hour period during each of the following phases: preluteolytic, luteolytic, and postluteolytic.
• The R program’s autocorrelation function was employed to detect rhythmicity of these pulses.
• The intra-assay CV (coefficient of variation) was used for identifying and characterizing these pulses of prolactin, and the metabolite of prostaglandin F2α referred to as PGFM.

Findings

• In the mares studied, rhythmicity of prolactin concentrations was exhibited by 67% of them, and 89% demonstrated rhythmicity in PGFM concentrations.
• An average of 5.2±0.4 hours was reported to be the time between the base of adjacent prolactin pulses.
• It was established that the peaks of prolactin pulses were significantly greater during the luteolytic period (46±14 ng/mL) and postluteolytic period (52±15 ng/mL) in comparison to the preluteolytic period (17±3 ng/mL).
• The study also reported that concentrations of prolactin during the hours of a PGFM pulse varied within the luteolytic and postluteolytic periods, with the highest concentration recorded at the peak of the PGFM pulse.
• The frequencies of the peak of prolactin and PGFM pulses occurring at the same time were greater in the luteolytic period (65%) and postluteolytic period (50%) compared to the preluteolytic period (17%).

Conclusion

• This study is the first report on the characterization and rhythmicity of prolactin and PGFM pulses in mares.
• It also establishes that prolactin activity is greater during the luteolytic and postluteolytic periods compared to the preluteolytic period.