Functional changes in luteinizing hormone-secreting cells from pre- and postpartum ewes

Area of Science:

• Reproductive Endocrinology
• Cell Biology
• Ovine Physiology

Background:

• Luteinizing hormone (LH) is crucial for reproductive functions.
• Changes in LH secretion occur during gestation and postpartum periods.
• The cellular mechanisms underlying these changes require further investigation.

Purpose of the Study:

• To investigate the correlation between morphological changes and the in vitro storage and secretion of LH in ovine pituitary cells.
• To determine the impact of gestation and parturition on LH-containing pituitary cells.

Main Methods:

• Ovine pituitaries were collected during gestation (days 50, 140) and postpartum (days 2, 13, 22, 35).
• Cells were enzymatically dissociated and cultured with or without steroids (estradiol, cortisol).
• Basal and GnRH-stimulated LH release, LH content, and cell morphology were assessed after 4, 7, or 10 days of culture.

Main Results:

• LH content per cell was lowest during late gestation and early postpartum, increasing significantly by day 13 postpartum.
• The percentage of LH-containing cells nearly doubled from day 2 to day 35 postpartum.
• LH-secreting cells were smaller with fewer secretory granules on day 2 postpartum compared to later stages.

Conclusions:

• Decreased LH synthesis during gestation is linked to hypoplasia of LH-secreting cells.
• These cells undergo reactivation and gradually regain normal LH synthesis capacity postpartum.
• Steroids in culture media did not influence LH secretion, suggesting intrinsic cellular regulation.