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Studies on the effects of altered timing of parturition in the rat
Manipulation of the length of gestation with two different agents has been compared and contrasted in the rat. Single subcutaneous injection of 1 mg/rat of PGF 2 alpha on day 19 of gestation caused premature parturition of at least 24 hours in 55% of treated rats. Premature parturition was associated with perinatal death and cannibalism of delivered pups. Subcutaneous implantation of pellets of naproxen over days 20-23 of gestation prolonged gestation to 24 days and synchronized onset of parturition compared to placebo-treated controls. Post-mature onset of delivery, in contrast, was associated with increased birth weight of pups and a survival rate of 90%. Post-mature pup deaths were restricted to the last pups delivered, i.e. longest gestation. The potential utility of naproxen for manipulation of time of parturition in domestic animals is suggested.
Manipulation of the length of gestation with two different agents has been compared and contrasted in the rat. Single subcutaneous injection of 1 mg/rat of PGF 2 alpha on day 19 of gestation caused premature parturition of at least 24 hours in 55% of treated rats. Premature parturition was associated with perinatal death and cannibalism of delivered pups. Subcutaneous implantation of pellets of naproxen over days 20-23 of gestation prolonged gestation to 24 days and synchronized onset of parturition compared to placebo-treated controls. Post-mature onset of delivery, in contrast, was associated with increased birth weight of pups and a survival rate of 90%. Post-mature pup deaths were restricted to the last pups delivered, i.e. longest gestation. The potential utility of naproxen for manipulation of time of parturition in domestic animals is suggested.