Abstract
Abstract
Arginine vasotocin (AVT) was given to cattle to determine its effects on concentrations of luteinizing hormone (LH) and prolactin (PRL) in serum. Doses of AVT ranging from 0.3 to 300 ü/kg BW, when given as single injection, did not alter the magnitude of frequency of normal pulsatile secretion of LH or concentrations of PRL in steers. Furthermore, AVT (0.7 mg/injection) given every 2 hr from −2 to 20 hr after 1 mg estradiol did not block the LH surge in ovariectomized cows. However, the 54% increase in concentrations of PRL which occurred 11 to 20 hr after injecting estradiol was blocked by repetitive injections of AVT. We conclude that AVT may alter PRL secretion in cattle. However, there is no indication that AVT affected LH release.
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