Effect of enzyme imprinting of liver microsomal monooxygenases upon lifespan of rats

Effect of the enzyme imprinting by phenobarbital upon alterations of hepatic microsomal mono oxygenase activities and lifespan of Wistar rats has been studied. Phenobarbital-sodium (3.5 mg/100 g body weight per day, i.p.) was injected during 1-3 days after birth. This resulted in the enzyme imprinting of the liver microsomal monooxygenases, however, this effect being observed in female but not male rats. In the phenobarbital treated female rats of different age the duration of sleeping time was significantly lower than that in control animals, whereas it did not differ substantially in male rats. The cytochrome P-450 content increased by 34.5% in phenobarbital treated female rats in the age of 12 months in comparison with control animals. A mean lifespan of experimental female rats increased by 17.5% compared to the level of control animals and did not change in male rats. The analysis of survival of animals in Gompertz equation coordinates showed that enzyme imprinting by phenobarbital caused changes in the mortality patterns at different stages of ontogenesis in experimental female but not male rats. An inverse correlation was found between the duration of pentobarbital sleeping time and lifespan of female and male rats. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.