Luteinizing hormone secretion and female lordosis behavior in male pigs
Ford, J.J.; Schanbacher, B.D.
Contraception Fertilite Sexualite 5(2): 1033-1038
1977
ISSN/ISBN: 0301-861X PMID: 12259792 Document Number: 432736
The effects of various treatments on serum concentrations of luteinizing hormone (LH) and testosterone (T) were investigated in male pigs during the 1st 9 weeks of life. In boars, T levels were constant during this period, while LH was elevated through Day 21, after which it declined to adult levels. When animals were castrated on Day 3, T concentrations fell, though there was no effect on LH levels until Day 21 when they increased to consistently greater levels than those found in boars. Treatment with LH-antiserum on Day 2 reduced T concentrations. Norethindrone decresed LH and T concentrations in 5-month-old boars, but had no effect when administered on Day 2. Estrogen decreased LH concentrations in 9-month-old animals during the 1st 48 hours of administration, but LH levels returned to pretretment values by 88 hours. Female lardosis behavior was observed in castrated males treated daily with estrogen. It is concluded that the negative feedback control of LH secretion is not operative in neonatal male pigs, and that estrogen can promote female lordosis behavior in castrated postpubertal animals.