Luteolytic effect of 13,14-dihydro-PGF-2 alpha in heifers.

Holstein heifers (4/group) were injected intramuscularly with 0, 5, 10 or 25 mg 13,14-dihydro-PGF-2 alpha on Day 10 of the oestrous cycle. Complete luteolysis and precocious oestrus occurred in 3 of 4 heifers receiving 25 mg and 1 of 4 receiving 10 mg 13,14-dihydro-PGF-2 alpha injected i.m. These features were not affected in heifers injected with 0 or 5 mg 13,14-dihydro-PGF-2 alpha, although plasma progesterone concentrations were depressed in all treated heifers within 75 min. LH concentrations were elevated between 5 and 8 h after 13,14-dihydro-PGF-2 alpha in all treated heifers. The addition of 13,14-dihydro-PGF-2 alpha to dispersed bovine luteal cells did not affect progesterone accumulation during a 2-h period. These results suggest that 13,14-dihydro-PGF-2 alpha may play a role in PGF-2 alpha-induced luteolysis.