Involvement of polyamines in the contragestational effect of hyperthermia.

Although hyperthermia produces teratogenic effects in a great variety of animal species, the molecular mechanisms by which hyperthermia exerts its action remain unknown. We have studied the implications of polyamines in contragestational hyperthermia in rats. Our results show that the contragestational action of hyperthermia when applied in consecutive periods during days 8, 9 and 10 of rat pregnancy could be completely prevented by the previous administration of polyamines (putrescine and spermidine, 0.6 mmoles/kg and 0.03 mmoles/kg respectively) in combination with the diamine oxidase inhibitor aminoguanidine or by this inhibitor alone (0.12 mmoles/kg). The administration of polyamines alone partially prevented the fetotoxic effect of hyperthermia but produced a marked mortality (50%) in the pregnant rats. These findings support a major and complex role of polyamines in the mechanisms of hyperthermia-mediated teratogenesis, and suggest that the oxidative catabolism of polyamines could be in part responsible of the deleterious effect produced by hyperthermia in rat pregnancy.