Summary. The effect of PGF-2α on LH release in immature ewes was studied. One intramuscular injection of PGF-2α induced LH release 36–72 h after treatment in 3/4 ewes. The LH variations were not associated with changes in the plasma concentration of progesterone and oestrogens. These results suggest that the LH release in immature ewes is due to PGF-2α acting at central structures.
G. Bono, R. Gaiani, and E. Seren
G. Bono, D. Minori, R. Gaiani, and M. Mattioli
Summary. Peripheral plasma levels of oestrone sulphate, androgens and LH were studied in two mating stallions. A peak of oestrone sulphate was observed 7·5–15 min after exposure to an oestrous female. No variations were recorded in LH concentrations. The concentrations of testosterone, dihydrotestosterone and androstenedione increased similarly after mating and on a day of sexual inactivity.
E. Seren, C. Tamanini, R. Gaiani, and G. Bono
Summary. Plasma concentrations of progesterone and 17α-hydroxyprogesterone were high in the 2nd and 3rd months of gestation, but 20α-dihydroprogesterone increased from a level of 2 ng/ml, during the first 3 months, to 10–15 ng/ml during months 5–10, to reach 80–120 ng/ml during the last 30 days before foaling.