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Blood LH after PGF2alpha in diestrous and ovariectomized cattle
Prostaglandins
|December 1, 1975
Summary
Prostaglandin F2alpha (PGF2alpha) increases luteinizing hormone (LH) in cattle. This study found that progesterone withdrawal, not estradiol, drives this PGF2alpha-induced LH surge in diestrous heifers.
Area of Science:
- Reproductive endocrinology
- Veterinary science
- Animal physiology
Background:
- Prostaglandin F2alpha (PGF2alpha) administration causes a rapid increase in serum luteinizing hormone (LH) in cattle.
- The precise hormonal mechanisms underlying this PGF2alpha-induced LH surge remain incompletely understood.
Purpose of the Study:
- To investigate the roles of progesterone and estradiol in mediating the acute increase in serum LH following a luteolytic dose of PGF2alpha in cattle.
Main Methods:
- Two experiments were conducted using diestrous and ovariectomized heifers.
- Hormone levels (LH and estradiol) were monitored after PGF2alpha administration with or without exogenous progesterone supplementation or withdrawal.
Main Results:
- Exogenous progesterone administration blocked the PGF2alpha-induced LH increase in diestrous heifers, but not in ovariectomized heifers.
- Removal of progesterone pessaries 6 hours after PGF2alpha injection led to a rapid LH increase, coinciding with a rise in estradiol.
Conclusions:
- The acute increase in serum LH following PGF2alpha treatment in diestrous cattle is dependent on the withdrawal of progesterone.
- Elevated serum estradiol is not the primary driver of this LH surge after PGF2alpha administration.