Influence of maternal nicotine exposure during gestation and lactation on lactate dehydrogenase isoenzyme profile and transcript levels in developing neonatal rat lung

In this study we investigated the effect of (a) aging on rat lung lactate dehydrogenase (LDH) mRNA expression and isoenzyme profile and, (b) the effect of maternal nicotine exposure during gestation and lactation on LDH isoenzyme profile and mRNA expression in the lungs of the offspring. Pregnant rats were injected subcutaneously (1 mg nicotine/kg body weight/day) from day 1 after mating. Lung tissue to determine LDH isoenzyme profile and mRNA expression was obtained from the offspring. LDH mRNA expression and isoenzyme profile was determined on postnatal days 1, 7, 14, 21 and 49. Generally the %Densities of all the isoenzymes decreased between postnatal days 1 and 49. Between postnatal days 7 and 14, a period associated with rapid alveolar formation, all isoenzymes except LDH-1, decreased (P < 0.01). During this period all the isoforms in nicotine-exposed lung increased (P < 0.05). In both control and nicotine-exposed lung LDH-1 is the dominant isoenzyme. The LDH-M and LDH-H isoenzyme levels are higher (P < 0.001) in the lungs of the nicotine exposed rats. Maternal nicotine exposure during gestation and lactation changed the metabolic status of the nicotine-exposed lungs to become more glycolytic compared to that of the control lung. These changes in LDH isoenzyme profiles and mRNA expression are irreversible.