Comparison of Testosterone and Androstenedione Secretion in Bulls Given Prostaglandin F2α or Luteinizing Hormone

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Abstract
In an experiment of latin square design each of six young bulls was given at 24-hr intervals 1) saline subcutaneously (sc) as a control, 2) 200 µg luteinizing hormone (LH) intravenously (iv), 3) 20 mg prostaglandin F2α (PGF2α) sc, 4) LH plus PGF2α, 5) LH plus PGF2α 1.5 hr later or 6) PGF2α plus LH 1.5 hr later. Jugular blood was sampled at frequent intervals during the experiment. Serum LH as measured by area under the response curve was greater after LH than after PGF2α treatment. Serum testosterone increased significantly after LH or PGF2α, but the increase was greater (P<.05) after administration of PGF2α alone than after LH or after simultaneous administration of LH plus PGF2α. Serum androstenedione was significandy correlated with testosterone after episodic secretion of LH and after exogenous LH or PGF2α. Based on these observations, we suggest that LH release after PGF2α administration may not be the only action of PGF2α in causing testosterone secretion in bulls. Copyright © 1978. American Society of Animal Science . Copyright 1978 by American Society of Animal Science.