Plasma LH concentrations after single or double injections of synthetic LH-RH in dairy cows.
Milked Friesian dairy cows were given 1 or 2 i.v. injections of synthetic LH-RH. The second of 2 injections of LH-RH given 1.5 h apart induced a significantly greater release of LH than did the first. The response to this injection was also significantly greater than that caused by injections given 6 h apart. There was no significant difference between the LH responses to the two injections given 6 h apart. The total LH release produced by the two injections of 100 microgram synthetic LH-RH given 1.5 h apart was significantly greater than that produced by single injection of 200 microgram synthetic LH-RH. It is concluded that there is a short-term increase in the responsiveness of the bovine pituitary gland to LH-RH after an initial LH-RH stimulus.
D000818:Animals; D002417:Cattle; D004334:Drug Administration Schedule; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage / Q000494:pharmacology*; D006728:Hormones / Q000008:administration & dosage / Q000494:pharmacology; D007986:Luteinizing Hormone / Q000097:blood* / Q000378:metabolism; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors
D006728:Hormones; D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone